Plant variety protection is one of the important approaches for plant intellectual property protection. The distinctness, uniformity and stability (DUS) and essentially derived variety (EDV) are two major concepts in plant variety protection. DUS-EDV has been evaluated largely through morphological traits and pedigrees at the very beginning, to an integrated approach using morphological traits, pedigrees and molecular marker information and now to a stage largely driven by molecular diagnostics. Molecular diagnostic technology has been evolved from RFLP to SSR and SNP marker systems. The liquid SNP chip, represented by genotyping by target sequencing through capture in solution, has advantages of low cost, high flexibility in marker combinations and wide suitability for DUS-EDV evaluation across plant species. There are two important strategies in DUS-EDV evaluation, one being examined based on the analysis and comparison at the whole genome level and the other being examined at specific genomic regions for target functional loci associated with important phenotypes. Evaluation criteria should be established separately for DUS and EDV. The former can be evaluated based on the criteria constructed for specific fingerprint maps, haplotypes, unique alleles, genomic regions, target functional markers, minimum genetic homozygosity, and within-variety variation, whereas the latter can be examined by the genetic similarity between the potential EDV and check variety estimated using a large number of molecular markers evenly distributed across the genome, rather than by the number of markers. The number and the genomic coverage of molecular markers are two key factors affecting the efficiency and reliability in DUS and EDV assessment. Using only a small number of markers in such assessment will likely result in a large sampling error for the estimates. The threshold of genetic similarity required for distinguishing EDV and non-EDV can vary greatly across plant species and with the levels of plant variety protection. After reviewed the current status of plant variety protection across countries, the authors proposed that a national consultant expert committee should be established for consistent support to implement and improve DUS-EDV system, and an official database system should be constructed for public service and comparison of variety DNA fingerprint data to facilitate innovative activities in plant breeding.

To ensure enough crop production of limited land area is important to food security. The key to solve this issue is to increase yield per unit area. Dense planting is an effective agronomic management practice to increase yield per unit area, photosynthetic rate would not be decreased or even improved by increasing planting density moderately, and then enhancing the yield per unit area. It is a key research focus on revealing the mechanism of photosynthetic physiology for improving yield per unit area by dense planting condition of maize. Dense planting would lead to change photosynthetic characteristics, so controlling the physiological factors that restricts photosynthesis is essential for increasing yield. Tap the photosynthetic physiologic potential for maize condition is physiological basis to ensure yield, which plays an important role in addressing food security issues. Therefore, this review focuses on the changes of the research methods and ideas in photosynthetic physiology, and the research status of the photosynthetic physiological response of maize adapted to dense planting and related agronomic regulation pathways at home and abroad, based on previous research results, so as to provide the theoretical and technical methods basis for photosynthetic physiology research. Based on the development trend of modern technology, it is believed that tapping photosynthetic potential and narrowing the gap between photosynthetic potential and actual photosynthetic efficiency are still the main goals of maize dense planting research by traditional research methods combined with molecular biology techniques in the future. In further study, research emphasis should be to investigate the responses of differential expression of photosynthetic physiological function genes to cultivation measures, clarifying the relationship and interaction between agronomic management practice and information expression of photosynthetic-related genes in densely planted maize, enhancing photosynthetic potential for maize via agronomic management practice and molecular biology technology, in order to provide photosynthetic physiological theory and practice to support for maize dense planting.

Annual wild soybean is the ancestor of cultivated soybean. The 100-seed weight gradually increases in the long-term domestication process. Clarifying the genetic basis of this change is of great significance to the evolutionary research and variety improvement of soybean. In order to analyze the genetic basis of 100-seed weight during soybean domestication, a wild soybean chromosome segment substitution line population (SojaCSSLP5) composed of 177 whole-genome resequencing lines were used in this study. 13 QTLs/segments of 100-seed weight were detected by phenotypic evaluation in three different environments. All of 13 wild chromosome segments had the additive effect of reducing 100-seed weight, ranging from -0.49 g to -1.19 g, which was consistent with the smaller 100-seed weight of wild soybeans. These detected domesticated segments from 11 chromosomes explained 76.70% of the phenotypic variation, and the phenotypic contribution rate of a single segment ranged from 2.45% to 15.14%. The contribution rate of segments Gm03_LDB_15 and Gm12_LDB_46 exceeded 10%, which were major influence on the evolution of 100-seed weight of wild soybeans. Combined the transcriptome data and genome data of parental cultivated soybean Nannong 1138-2 and wild soybean N24852, a total of 13 candidate genes were predicted in these segments, and were involved in the pathways of plant seed size, including ubiquitin protein kinase regulatory pathway, G protein signal pathway, mitogen-activated protein kinase pathway, plant hormone pathway, transcription regulator pathway, and IKU (HAIKU) pathway. Compared with previous QTLs mapping results with cultivated soybeans, 4 of the 13 QTLs/segments were newly detected in this study, indicating that 9 wild chromosome segments might be passed to cultivated soybeans during domestication, and the corresponding cultivated segments of these 4 wild segments may be unique evolutionary segments of cultivated soybean.

The thickness of pod reticulation is not only an important criterion of peanut taxonomy, but also an agronomy trait related to peanut mechanical harvesting. To explore the genetic mechanism of reticulation thickness of peanut pods, a novel phenotyping method was developed to determine the reticulation thickness through reconstructing three dimensional (3D) models of pods. Meanwhile, a recombinant inbred line (RIL) population (181 lines) was derived from a cross between Huayu 36 and 6-13 and planted in three environments from 2019 to 2020, including Qingdao, Dongying, and Weihai of Shandong province. Phenotypic data of the RIL population were collected from these three environments. Two related traits, thicknesses of latitudinal and longitudinal protuberant veins (reticulations), had continuous and transgressive distributions in the RIL population, with broad-sense heritablities of 0.92 and 0.91, respectively. Based on a previous high density genetic map, a total of 11 additive QTLs were identified explaining phenotypic variations of 5.21%-11.06%, among which six QTLs were related to thickness of latitudinal protuberant vein and five related to thickness of longitudinal protuberant vein. Two major loci, qLA2 and qLO9 could be detected in more than one environments, with contributing alleles coming from Huayu 36 and 6-13, respectively. A total of 22 pairs of epistatic QTLs involving 34 loci were identified explaining phenotypic variations of 0.55%-4.37%, among which 10 pairs of interactions were related to thickness of latitudinal protuberant vein and 12 pairs were related to thickness of longitudinal protuberant vein. These results provide valuable information for further gene mapping and molecular breeding in peanut.

The number of grains per spike is one of the three key factors for yield and production in wheat. It is helpful to cultivate high-yield wheat varieties to elaborate the regulation pathway of spike development. A stable mutant of apical spikelet degeneration (asd1) was derived by EMS treatment, the wheat variety Jing 411 was used as wild type. The mutant asd1 showed that the apical spikelets were significantly degenerated, the spike length was shortened by 40%, the number of spikelets per spike was reduced by 35%, the number of grains per spike was significantly reduced by 54%, and the plant height was also significantly reduced. A genetic segregation population, Jing 411 × asd1, was developed, and phenotypic performances of both F₂ and F₃ were investigated in field. It showed that the degeneration of apical spikelet was controlled by a recessive gene. Using Bulked Segregant Analysis (BSA) and exon capture, SNPs were obtained and 7 KASP markers were further developed. The target mutation gene was mapped on chromosome 7A and narrowed down to a 9.91 Mb region on 7AS, which represented a genetic distance of 17.62 cM. The region had not yet been reported in regulating spikelet development and the target mutant gene might be a novel gene that controls the development of spike morphology in wheat, which will bring new insights for further understanding of the genetic basis of spikelet development in wheat.

China is the birthplace of foxtail millet, four traditional foxtail millet accessions of Qinzhouhuang, Taohuami, Longshanxiaomi, and Jingumi because of its good quality characteristics, has been selected as the royal tribute and is loved by people in Chinese history. To explore the genetic diversity of four Chinese famous foxtail millet and the genetic relationships among the namesakes, SSR and SRAP markers were used to analyze the genetic difference of 179 foxtail millet varieties. Results based on SSR markers showed that the genetic distance ranged from 0.0435 to 0.6304 with an average of 0.3267, the PIC was 0.2406, the allele frequency was 0.7845, and the genetic diversity was 0.2968. Based on UPGMA, 179 materials were clustered into 10 groups, and the clusters had certain correlation with their sources. The materials were divided into three groups based on structure and three groups based on principal component analysis. SRAP marker analysis revealed that the genetic distance ranged from 0.1818 to 0.9545 with an average of 0.6001, and the PIC, the allele frequency, and the genetic diversity were 0.5257, 0.5718, and 0.5688, respectively. Based on UPGMA, 179 materials were clustered into 14 groups. The materials were divided into three groups based on structure and principal component analysis. The groups were clearly divided and the origin of the groups was consistent with their source.

The kernel size affects kernel weight in wheat, and then affects yield. Up to date, the genes related to kernel size have been reported in bread wheat. However, the underlying molecular mechanisms that regulates the size of wheat kernels remains unclear. In this study, the TaGS2 gene related to kernel size was successfully cloned from bread wheat based on in silico cloning and its sequence was analyzed by bioinformatics. Subcellular localization analysis of tobacco indicated that TaGS2 was localized in the nucleus and cytoplasm. Relative expression levels of different tissues showed that the TaGS2 gene was highly expressed at different developmental stages of the kernels. RNA interference vector TaGS2-PLGY-02-RNAi was constructed and transferred into wheat. The results indicated that the relative expression levels of TaGS2 gene was significantly reduced in RNAi transgenic wheat. In addition, the kernel length and width of RNAi transgenic wheat was shortened, and the thousand-kernel weight was reduced as well. Therefore, it was speculated that TaGS2 gene was probably involved in the regulation of wheat kernel size or thousand-kernel weight. This study preliminarily reveals the TaGS2 gene function and provides important genetic resources for the improvement of thousand-kernel weight in wheat breeding program.

Flowering time, an important agronomic index of crops, is related to the growth cycle and the yield of crops. Sugar transporters are important carbohydrate transporters in plants, whereas there are few reports on the effect of sugar transporters on flowering time in rapeseed (Brassica napus). In this study, sucrose transporter Bna.C02SWEET15 related to flowering in rapeseed were screened and identified from Fox-Hunting library, whose biological function and regulation mechanism were further characterized through expression pattern and subcellular localization analysis, phenotype analysis in transgenic plants and mutant, detection of marker genes expression related to flowering. Bna.C02SWEET15 could be identified in all tissues of Brassica napus, and the relative expression level was the most significant in seeds at 30 days after flowering. Bna.C02SWEET15 was located in cell membrane, and the promoter activity was mainly in anther and seed at 30 days after flowering. Overexpression of Bna.C02SWEET15 in Arabidopsis resulted in flowering in advance and increased the expression of photoperiod key genes CO, FT, and LFY, while decreased the expression of negative regulation gene FLC. In addition, the flowering time of atsweet15a and transgenic RNAi-Bna.C02SWEET15 were later. We proposed that Bna.C02SWEET15 could positively regulate the flowering time through photoperiod pathway, thus affecting the growth cycle and final yield in rapeseed. These results provide important basis for understanding the regulatory role of sugar transporters in crops and lay a theoretical foundation for understanding the regulatory role of sugar transporters in crops.

Seed shattering is an important trait for seed dispersal and reproduction of offspring in wild rice. It is a vital guarantee for seed dispersal and offspring reproduction of wild rice, but easy grain dropping will cause yield loss in domesticated rice production. Although some genes related to seed shattering have been cloned in rice, these genes were not responsible for all phenotype variation of rice seed shattering. In this study, a recombinant inbred line (E6-5) was selected from a cross between an indica variety Pei-kuh and an Asian common wild rice W1944 and hybridized with Pei-kuh to construct the isolated population. E6-5 harbored W1944 introgression segment on chromosome 8, but it had not carried SH4 gene and exhibited a very easy seed shattering phenotype. By analyzing an F₂ segregation population constructed using E6-5 and Pei-kuh, we narrowed down the SHATTERING8 (SH8, qSHT-8) in the 26.4 kb interval. There were four protein-coding genes in this region. The comparison of PEI-Kuh and E6-5 sequencing revealed that LOC_Os08g41950 contained three single nucleotide polymorphisms (SNPs) in coding region. Meanwhile, qRT-PCR revealed that LOC_Os08g41950 was expressed in the junction of flower and pedicel, where the abscission layer was formed and shed off. We considered LOC_Os08g41950 as the candidate gene for SH8. To verify whether LOC_Os08g41950 was responsible for rice seed shattering, we constructed an overexpression vector using LOC_Os08g41950 encoding sequence from E6-5 and transformed it into Pei-huh. Compared with Pei-kuh, the shattering ability of transgenic plants was significantly enhanced. In addition, consistent with the BTS testing results, transgenic plants had smoother fracture surface of pedicel compared with that of Pei-kuh in scanning electron microscopy photos. These results would facilitate the study of rice domestication and seed shattering regulation mechanism.

Soybean nutritional quality traits are generally quantitative traits and are regulated by multiple genes. At present, a large number of molecular markers related to quality traits have been located, but there were few available markers verified in soybean breeding populations. In this study, we selected 288 soybean varieties from Huang-Huai-Hai region and 19 wild/ semi-wild soybean accessions as a natural population. We analyzed their protein, oil, fatty acid, and isoflavone contents by NIR, GC, and HPLC methods. We selected 18 SSR markers closely linked to quality traits to identify their genotypes by capillary electrophoresis method, and verify the molecular markers associated with nutritional quality traits using association analysis based on the Tassel 2.1 software. The results showed that there were three markers associated with oil content, three markers associated with the content of protein plus oil, one marker associated with palmitic acid, one marker associated with stearic acid, two markers associated with oleic acid, and two markers associated with linolenic acid, and the elite alleles of these loci were also investigated. Our study provided reliable molecular markers for soybean quality molecular breeding.

Proline accumulation is an important metabolic adaptative mechanism of plants under biotic and abiotic stress. P5CS, P5CR, PDH, and P5CDH are key enzymes in the glutamate-dependent proline biosynthesis pathway. Rapeseed, an important oil crop in the world, is often subjected to various biotic and abiotic stresses during its growth and development. However, no systematic analysis of these proline metabolic gene families has been reported in Brassica napus so far. In this study, 10 BnaP5CSs, 6 BnaP5CRs, 8 BnaPDHs, and 3 BnaP5CDHs were identified by using the genomic annotation information of ‘Zhongshuang 11'. Phylogenetically, these gene families were divided into different evolutionary branches, and members of the same subgroups had similar physical and chemical properties, gene / protein structure, and conserved motifs. Evolutionary pressure analysis showed that these genes were subjected to strong purification selection. Cis-acting element analysis revealed that there were common and specific transcriptional regulatory mechanisms among the four kinds of gene families. In this study, rapeseed seedlings were respectively treated with salt stress, low potassium (K), low phosphate (P), and ammonium toxicity, and both shoots and roots were respectively sampled for transcriptomic analysis. The results indicated that the relative expression levels of genes related to proline synthesis were generally up-regulated under the above-mentioned four stresses, whereas the relative expression levels of genes regulating proline degradation were down-regulated under salt and low P stresses. Gene co-expression network analysis demonstrated that BnaC4.P5CS1a and BnaA5.P5CS1 might play central roles in the proline-mediated stress responsive networks in rapeseed. Through bioinformatics identification of proline metabolism gene family and analysis of transcription characteristics under various abiotic stresses, this study will provide a theoretical basis for further study of proline-mediated stress resistance, and will also provide excellent gene resources for genetic improvement of abiotic stress resistance mediated by proline metabolism in Brassica napus.

In this study, hybrid maize (Zea mays L.) cultivar ‘Zhengdan 958' seeds were used as materials to reveal the mechanism of seed aging. After artificial aging treatment (45℃, 100% relative humidity), the seed vigor, O₂^- production, ATP content, and ATP synthase activity of seed embryo were investigated, and the integrity of ATP synthase subunit mRNAs in seed embryo and different organs (scutellum, radicle, and plumule) was analyzed by the reverse transcription blocking and double-primer amplification method. The results showed that the germination rate and radicle growth rate of maize seeds decreased, the viability of embryo decreased and the respiration intensity of seeds decreased after artificial aging treatment. The O₂^- production rate in embryo reached the peak on the 3rd day of aging treatment, and then decreased, the O₂^- production rate and content in radicle and plumule increased significantly. The ATP content and ATP synthase activity in embryo decreased. The mRNA integrity of ATP synthase ε-subunit and γ-subunit increased first and then decreased. The mRNA integrity of δ-subunit did not change significantly. The mRNA integrity of α-subunit and β-subunit decreased continuously in artificial aging treatment. The damage degree of mRNA integrity of ATP synthase subunits in radicle and plumule was much greater than that in scutellum. These results revealed that the production and accumulation of ROS in radicle and plumule could lead to different degrees of damage to ATP synthase subunit mRNAs and the activity of ATP synthase and the content of ATP in embryo decreased, which resulted in the lack of energy supply during germination, and this maybe one of the major factors causing maize seed aging.

Rice is a salt-sensitive crop, and salt stress can cause significant reduction in rice yield. China's total saline area is large and growing rapidly. Therefore, it is necessary to screen for the salt-tolerant rice germplasm and cultivate these varieties. In this study, we evaluated the relative salt damage rate of 419 core germplasm of Guangxi rice landraces at seed germination stage under 1.5% NaCl salt stress, and identified the salt-tolerant loci by whole-genome association analysis. The results showed that the average germination rate under salt stress was 57.67%, which was significantly 92.55% lower than that of control group, and the Shapiro-Wilk test (0.9301) found that the distribution did not conform to normal distribution. Based on 208,993 SNP markers, 419 core germplasm was divided into 6 subgroups. We used general linear model (GLM) and mixed linear model (MLM) analysis to identify 129 and 1 significantly associated SNPs, respectively, which were distributed on chromosomes 1, 2, 3, 4, 5, 6, 8, 9, and 12. Among the 14 regions that were significantly associated with rice salt tolerance, 13 regions overlapped with previously identified or cloned salt tolerance genes. The significantly associated region Chr. 8:10,564,948-10,733,175 was reported for the first time and named qGR8. There were 53 genes in qGR8 region, 34 of which were compared with transcriptome data to obtain the expression profiles. We compared the expression profiles and speculated that LOC_Os08g17370 was a candidate gene. This gene is a member of transmembrane 9 superfamily and is up-regulated in roots and leaves of salt-tolerant parent. Thus, this gene might be a novel salt-tolerant gene in qGR8 region at germination stage in rice. These results lay a foundation for cloning new genes of salt-tolerant and provide new genetic resources for breeding salt-tolerant rice varieties.

Early rice easily suffers from low temperature injury at seedling raising stage, resulting in yield reduction. Therefore, it is necessary to develop low temperature tolerant rice seedling substrate to ensure early rice production. The fermentation substrate made by ourselves was used in the present study. After melatonin and methyl jasmonate were added in the substrate, the rice was treated with low temperature for 3 days at seed germination stage and 7 days' growth stage. Then, to clarify the regulatory mechanism of these two phytohormones on the tolerance of early rice seedlings to low temperature stress, the germination status, physical and chemical properties, and gene expression of rice were explored. The results showed that both melatonin and methyl jasmonate could significantly improve the seed germination rate and germination potential of rice under low temperature. Both could improve the growth of rice, including plant height, root length, root number, dry matter weight, leaf age, and nutrient content. Under low temperature, melatonin and methyl jasmonate both reduced hydrogen peroxide and malondialdehyde content in rice by regulating the activities of antioxidant system enzymes, so as to alleviate the lipid peroxidation damage caused by low temperature stress. Melatonin and methyl jasmonate both increased the contents of proline and chlorophyll, and decreased the content of abscisic acid in rice under low temperature stress. Methyl jasmonate along increased GA₃ content in rice under low temperature conditions. Melatonin and methyl jasmonate had different regulatory effects on cold tolerance genes expression in rice. Both of them significantly up-regulated the relative expression of OsCDPK7 and OsLti6b genes, and down-regulated the expression of OsWRKY45 gene in rice under low temperature conditions. In addition. The relative expression of OsFer1 gene was induced by melatonin alone, while the relative expression of OsTrx23 gene was up-regulated by methyl jasmonate alone in response to low temperature stress. The above results showed that both melatonin and methyl jasmonate could improve the low temperature stress tolerance of rice by regulating the enzyme activity of antioxidant system, osmotic substance content, chlorophyll content, plant hormone content and the expression of cold tolerance genes in rice.

The application of panicle nitrogen fertilizer is an important management measure to increase rice yield, but its effect and mechanism of application rates on the yield increase of super rice varieties with different panicle sizes are still unclear. In this study, three super rice varieties with large differences in panicle sizes (indicated by the spikelet number per panicle) of Nanjing 9108 (small panicle size), Yangliangyou 6 (medium panicle size), and Yongyou 1540 (large panicle size) were selected as materials. Under the condition of the same amount of base-tiller fertilizer (162 kg N hm^-2), the effects of five panicle nitrogen fertilizer rates (PNR) of 0, 54, 108, 162, and 216 kg hm^-2 on the yield of the above rice varieties were studied. And its regulatory effects on the differentiation and degeneration of spikelets and related morphophysiological indices after heading were observed. The results were as follows: (1) In the PNR range of 0-216 kg hm^-2, the spikelet number per panicle gradually increased but the seed-setting rate and 1000-grain weight gradually decreased with the increase of PNR. And the higher the PNR, the more obvious the decrease of seed-setting rate and 1000-grain weight. Three rice varieties, Nanjing 9108, Yangliangyou 6, and Yongyou 1540, had the highest yields in the PNR of 162-216, 108-162, and 54-108 kg hm^-2, respectively. According to the curve equation of grain yield and PNR, the optimal PNR for high yields of the above three varieties were calculated to be 177.6-182.0, 134.3-136.3, and 109.9-125.7 kg hm^-2, respectively. (2) In general, rice varieties with large panicle sizes had higher yields, while rice varieties with small panicle sizes had greater yield-increasing effects of PNR. The number of differentiated and surviving secondary spikelets in rice varieties with small panicle size increased greatly after application of panicle nitrogen fertilizer, which was the main reason that the yield-increasing effect was higher than that of rice varieties with medium and large panicle size. (3) Under the condition of high-yield PNR, high effective leaf area ratio, grain-leaf ratio (spikelet/leaf area, filled grain/leaf area, and grain weight/leaf area), non-structural carbohydrate (NSC) translocation amount, sugar-spikelet ratio, root oxidation activity, activity root of spikelet and zeatin (Z) + zeatin riboside (ZR) content in grains and roots from 0-40 day(s) after heading of three rice varieties were high. Correlation analysis showed that the yields of super rice varieties with different panicle sizes and the above indicators basically had a significant or extremely significant positive correlation. These results indicated that the PNR should be adjusted according to the panicle size. The appropriate PNR was beneficial to maintain a high effective leaf area ratio, grain-leaf ratio, NSC translocation amount, sugar-spikelet ratio, root oxidation activity, activity root of spikelet, and Z + ZR content in grains and roots after heading under the premise of higher total spikelets. This helped to maintain a high seed-setting rate and grain weight, thereby ultimately increasing the grain yield.

The development of cotton intercropping system is the main strategy to alleviate the conflict between cotton and other crops for land in the Yellow River Basin of China, but the mechanism of cotton yield increases in cotton intercropping system is still unclear. In this study, a two-year field experiment with cotton-based intercropping systems (wheat/cotton, garlic/cotton, and peanut/cotton) and three root partitions (no, mesh, and plastic partitions) to study the effects of different crops intercropped with cotton on yield, biomass accumulation and allocation. The study showed that: (1) The land equivalent ratios (LERs) of different crops intercropped with cotton were greater than 1, indicating that the cotton intercropping system in the experiment had intercropping advantage. The resource competitiveness of wheat and garlic relative to cotton was greater than 0, indicating that wheat and garlic were dominant species in the co-growth period of wheat/cotton intercropping and garlic/cotton intercropping systems, whereas the resource competitiveness of peanuts relative to cotton was less than 0, indicating that cotton was dominant species in peanut/cotton intercropping system. (2) Dry matter accumulation of the leaf and stem in sole cotton cropping system was more than that of intercropping systems at bud stage, while the dry matter accumulation in intercropping systems was more than that in sole cotton cropping after the flowering and boll stages. The reproductive organs dry matter accumulation in intercropping systems was also higher than that in sole cotton cropping system. (3) The distribution rate of the stem and leaf in sole cotton was significantly higher than that in cotton intercropped with wheat, garlic, and peanut at bud stage and initial flowering stage, but the difference was not significant at full-bloom and open boll stages. However, the opposite pattern was observed in dry matter distribution rate of reproductive organs. These results can provide theoretical support for the mechanisms of cotton intercropping advantage and scientific basis for the productivity improvement of intercropping systems.

To compare the characteristics of vascular bundle of peduncle and flag leaf and assimilate translocation of stems and leaves and to explore the relationship between the characteristics of vascular bundle and the assimilate translocation of stems and leaves and yield formation, four different types of rice varieties were selected and studied, including indica hybrid rice, indica-japonica hybrid rice, indica conventional rice, and japonica conventional rice. The results showed that there were differences in genotypic phenotypes among the number and anatomical characteristics of vascular bundles of peduncle and flag leaf and non-structural carbohydrate (NSC) translocation in stems and leaves among different rice varieties. Among the four different types of rice varieties, the number of vascular bundles, average cross-section area and phloem area of peduncle and flag leaf of indica hybrid rice and indica-japonica hybrid rice were higher than those of the other two types of rice varieties, and the stem and leaf NSC translocation and yield were also higher than those of the other two types of rice varieties, followed by indica conventional rice. The vascular bundle number, average cross-sectional area and phloem area of peduncle and flag leaf in japonica conventional rice was the lowest, and the NSC translocation and yield of stem leaf was also the lowest. The characteristics of the vascular bundle and the translocation of stems and leaves NSC were affected by nitrogen application levels. Low nitrogen could promote the NSC translocation of stems and leaves, high nitrogen application could increase the number of vascular bundles, the average cross-section area and phloem area of peduncle and flag leaf, but the density of the cross-section vascular bundle of peduncle was decreased. Correlation analysis showed that the number of large and small vascular bundles of peduncle and flag leaf was significantly or extremely significantly positively correlated with NSC translocation of stems and leaves, the number of large and small vascular bundles, average cross-section area and phloem area of peduncle and flag leaf were significantly or extremely significantly positively correlated with yield. In conclusion, selecting rice varieties with well vascular bundle phylogeny and rational application of nitrogen fertilizer can improve the characteristics of vascular bundle, facilitate the translocation of assimilate in stems and leaves, and promote grain yield.

Cold temperature and cold damage is one of the important abiotic stress factors restricting the development of peanut industry. The ability of peanut varieties to tolerate cold at germination stage is an important guarantee to determine the uniformity of seeding emergence, high yield, and high quality. In this research, 62 peanut varieties with different genotypes were comprehensively assessed for cold tolerance at germination stage by using comprehensive index value, weight, membership function value, and D-value of each variety. The results showed that the higher the D-value, the stronger the cold tolerance, and vice versa. The 62 varieties were divided into five categories by systematic cluster analysis: the first category was high cold-tolerant, the second was cold-tolerant, the third was intermediate cold-tolerant, the fourth was sensitive, and the fifth was highly sensitive. Correlation analysis revealed that the correlations between oleic acid content and D-value and other four indexes of cold tolerance did not reach a significant level, indicating that the acid content of peanut oil had nothing to do with the cold tolerance in peanut germination stage. A significant positive correlation between each relative index value and D-value indicated that there was consistency among the relative index values of cold tolerance in peanut germination stage. The analysis of its relative index characteristic value, contribution value, and weight demonstrated that the relative germination rate could be used as the positive index of cold tolerance identification in peanut bud period, that is, the greater the relative germination rate, the stronger its cold tolerance at germination stage, and vice versa. Five varieties with high cold-tolerance were selected, and the relative germination rate as the evaluation index of cold-tolerance in peanut germination stage was established in this study, providing basic materials and efficient assessing methods for the quick assessment of cold-tolerant peanut germplasm in peanut germination stage, cultivation of new varieties with cold-tolerance and related theoretical researches.

The objective of this study is to explore the effect of soil moisture on the formation of storage roots in sweet potato and its relationship with the number and uniformity of storage roots. In this experiment, the sweet potato variety Yanshu 25 was used as the experimental material. We performed five soil relative water content levels with 50%±5% (W50), 60%±5% (W60), 70%±5% (W70), 80%±5% (W80), and 90%±5% (W90) at root branching stage. The effects of soil moisture on the content of carbohydrate and the activity of metabolic enzymes in the potential storage roots, as well as the number, uniformity and yield of storage roots at the harvest time were studied by a two-year field experiment. The results showed that the content of sucrose, glucose, and fructose and the activity of sucrose invertase in the potential storage roots of sweet potato in W70 treatment were significantly higher than those of other treatments during 10-35 days after planting. The activity of sucrose synthase and the content of starch in the potential storage roots of sweet potato in W70 treatment were significantly lower than those of other treatments at 10-25 days after planting, while the trend was opposite during 30-35 days after planting. Compared with other treatments, the number of storage roots per plant and the yield of storage root in W70 treatment increased by 14%-120% and 22%-122%, respectively. The variable coefficient of the single storage root weight decreased by 9%-34%. The soil relative water content of 70% at root branching stage of sweet potato was beneficial to the formation of storage roots, which increased the number of storage roots per plant, weight of the single storage root and yield of storage roots, and improved the commercial quality of storage roots at harvest time.

Acid red soil is characterized by high acid and low calcium, which seriously affects seed germination and plant morphogenesis. Both calcium and spermosphere soil microorganisms play important roles in regulating seed germination, but the mechanisms underlying their relationship are little understood. Improving the emergence and healthy seeding rate of peanut is one of the effective strategies for efficient cultivation of peanut in acidic red soil. To reveal the potential effects of calcium nutrition on the spermosphere microbial community structure and seed germination in peanut, pot experiments were conducted on Huayu 20 (HY20) with or without calcium application, and the spermosphere microbial structure during the germination process was analyzed using high-throughput sequencing. The results showed that Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes were the dominant bacterial phyla, while Ascomycota, Basidiomycota, and Mortierellomycota were the dominant fungal phyla in peanut spermosphere. CaO application increased the relative abundance of Firmicutes, Bacteroidetes, and Mortierellomycota, but decreased the relative abundance of Basidiomycota. In addition, calcium application increased the number of beneficial bacteria Bacillus. Function prediction analysis indicated that the pathways related to organic matter metabolism (amino acid transport, and metabolism, carbohydrate transport, and metabolism) and stress resistance (replication, recombination, and repair) were significantly increased after the application of calcium, which improved the germination environment of peanut seeds in acid red soil to a certain extent. FUNGuild trophic modes analysis revealed that the number of symbiotroph was increased while the number of saprotrophs was decreased after CaO application. Redundancy analysis indicated that the bacterial and fungal structure was negatively correlated with soil physical and chemical factors, calcium content and pH value. Moreover, the calcium content in soil may have a greater regulatory effect on soil microbial diversity than pH. Based on the above studies, the application of calcium in acidic red soil can improve spermosphere microbial structure, resulting in promoting seed germination.

Elucidating the metabolic mechanism of plants under saline-alkali stress will help to further optimize breeding and cultivation, thereby increasing crop yields in saline-alkali soils. In this study, to analyze the differences in cotton metabolism under salt-alkali stress, liquid chromatography-mass spectrometry (LC-MS) was used to study the metabolites of cotton leaves under neutral salt and alkaline salt stress. The results showed that under salt stress, 7 and 2 types of sugars in cotton leaves were up-regulated in positive and negative ion modes, 3 types of amino acids were up-regulated, and 12 and 8 types of organic acids were up-regulated in cotton leaves under alkali stress. There are three kinds and five kinds of up-regulation in sugars, two kinds and nine kinds of up-regulation in organic acids, and two kinds of up-regulation in amino acids. 10 differential metabolic pathways were detected under salt stress. The most obvious metabolic pathway was linoleic acid metabolism, followed by starch and sucrose metabolism and arginine biosynthesis. Five differential metabolic pathways were found under alkaline stress. The most significant metabolic pathway was tryptophan metabolism, followed by arginine and proline metabolism and citric acid cycle (TCA cycle). Cotton adopts different metabolic mechanisms to resist salt-alkali stress. Salt stress tended to accumulate sugars and alkali stress tended to accumulate organic acids. In terms of energy metabolism, cotton starch and sucrose metabolism was more active under salt stress, and TCA cycle was more active under alkali stress. Salt stress improves the nitrogen assimilation ability of cotton, and alkali stress reduces the nitrogen assimilation ability.

The objective of this study is to clarify the effects of returning different materials on photosynthetic performance and nitrogen metabolism of summer maize, and to provide a theoretical basis for the effective use of agricultural wastes. Field experiments were conducted on calcareous purple soil in hilly areas of central Sichuan in 2018 and 2019. Four treatments were set up, including no material returning (CK), faba bean straw (faba bean straw, FS), rape straw (rape straw, RS), and pig manure (pig manure, PM) returned. The yield, photosynthetic performance, and nitrogen metabolism of summer maize by different materials returned were studied. The experimental results show that: (1) By different organic materials returned, the effect of FS in the second year on maize grain yield was the best, which was significantly increased by 24.85% compared with the CK. (2) The leaf area index, leaf area accumulation rate, leaf area duration, and photosynthetic pigment content of summer maize each material returned all increased first and then decreased with the growth period. Compared with CK, FS, and PM could improve leaf area index, leaf area accumulation rate, and leaf area duration of summer maize, but the effect of RS was decreasing. The photosynthetic pigment content of summer maize at 6-leaf stage was not significantly different among treatments. The chlorophyll b, total chlorophyll, and carotenoid content of RS at silking stage were the higher than CK. At 20 days after silking, the contents of chlorophyll a, b, and total chlorophyll of FS were significantly increased by 34.67%, 42.08%, and 36.24% compared with RS, respectively. (3) Organic material returned significantly increased the nitrate reductase activity of summer maize, and the nitrogen accumulation and transport in vegetative organs of each returning treatment were FS, PM > RS. The results of principal component analysis revealed that the photosynthetic performance and nitrogen metabolism capacity of summer maize by different materials returned to the field were FS > PM > CK > RS. In summary, the effects of different organic materials returned on photosynthetic performance and nitrogen metabolism of maize were different. Compared with no material and rape straw returned, faba bean straw and pig manure returned can improve the photosynthetic nitrogen metabolism ability of leaves, promote the transport of photosynthetic metabolites in vegetative organs to grains, and lay the foundation for the increase of grain yield of summer maize.

The mutant sr10 (slender rice 10) reported in this study was obtained by ethyl methanesulfonate (EMS) from Xinong 1B, an indica maintainer line and it was slender stems and male sterility. Cytological observation indicated that the size of mutant cells became longer while the number of vascular bundles was less than wild type. The frozen section and chlorophyll content measurement manifested that the chlorophyll content of sr10 decreased greatly, resulting in the decreased photosynthetic rate, but the falling of stomatal conductance might improve its drought resistance. The levels of IAA and GA₃ were significantly increased, while the content of ABA was sharply decreased in sr10. QRT-PCR analysis manifested that some genes involved in GAs pathway were down-regulated and some of IAA pathway related genes were abnormal. Genetic analysis suggested that the mutant phenotype of sr10 was controlled by a single recessive nuclear gene. The SR10 was located at a 175.7 kb interval between the molecular markers LIND12 and 28.5-4 on chromosome 3. These results laid a foundation for cloning and functional analysis of SR10.