Table of Content

12 January 2016, Volume 42 Issue 01

Previous Issue    Next Issue

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Regulating Effects of GmMYB042 Gene on Flavonoid Biosynthesis

DU Hai, RAN Feng,MA Shan-Shan,KE Yun-Zhuo,SUN Li-Ping,LI Jia-Na,TANG Yi-Xiong

Acta Agron Sin. 2016, 42(01):  1-10.  doi:10.3724/SP.J.1006.2016.00001

Abstract ( 787 )   RICH HTML    PDF (2713KB) ( 3503 )   Save

References | Related Articles | Metrics

MYB transcription factor is one of the largest transcription factor gene families in land plants, and is involved in a myriad of regulatory processes, such as secondary metabolism. In the present study, the expression profiles and function of GmMYB042 gene were systematically studied. In order to investigate the roles of the conserved amino acid motif PDLNLELTIS and a predicted zinc finger region at its C-terminal, a series of sequence deletions of these two regions were made by PCR method. Subsequently, the corresponding over-expression constructs of GmMYB042 gene and its mutants were made and transformed into tobacco NC89 with Agrobacterium LBA4404, respectively. Expression analyses revealed that GmMYB042 gene was expressed in nodule, root, stem, leaf, flower, pod and seed of soybean, and with a relative higher expression level in stem, flower and seed; its expression could be induced by PEG, high salt, low temperature and UV-B radiation stresses. Over-expression analyses showed that the expressions of some enzyme genes in flavonoid biosynthesis pathway (including PAL, CHS, CHI, and FLS) were obviously increased in GmMYB042 transgenic lines, resulting in an increased content of the flavonoid compounds. Accordingly, the transcription levels of the corresponding enzyme genes involved in flavonoid biosynthesis pathway were decreased in the transgenic lines of GmMYB042 mutants, further supporting the conclusion of regulating role of GmMYB042 gene in tobacco flavonoid biosynthesis pathway.

Sequence Polymorphism and Cumulative Effect with 6-SFT-A2 of Fructan Biosynthesis Gene 6-SFT-D in Wheat

YUE Ai-Qin,LI Ang,MAO Xin-Guo,CHANG Xiao-Ping,LIU Yu-Ping,LI Run-Zhi,JING Rui-Lian

Acta Agron Sin. 2016, 42(01):  11-18.  doi:10.3724/SP.J.1006.2016.00011

Abstract ( 855 )   RICH HTML    PDF (649KB) ( 1607 )   Save

References | Related Articles | Metrics

Gene 6-SFT encodes a key enzyme in fructan biosynthesis pathway in common wheat (Triticum aestivum L.). In this study, we analyzed the single nucleotide polymorphism (SNP) on 6-SFT-D locus in a diversity population of 23 hexaploid wheat (AABBDD) accessions and five wheat relative species (DD) by means of direct sequencing. Functional markers were developed according to the sequence polymorphism. The correlation between 6-SFT-D haplotypes and phenotypic traits and the cumulative effect of 6-SFT alleles were analyzed using a natural population consisting of 154 historical wheat accessions. Four SNPs were detected on 6-SFT-D locus in the diversity population, forming three haplotypes. However, only two 6-SFT-D haplotypes were identified in the natural population. We developed a pair of allele-specific PCR markers based on a polymorphism (T/C) at the 2850 bp site. The results of haplotype–trait association analysis showed that 6-SFT-D was significantly associated with thousand-grain weight (TGW) and spike length under well-watered conditions. HapI was superior in improving TGW. Under drought stress and well-watered conditions, wheat materials carrying both 6-SFT-D and 6-SFT-A2 had significantly higher TGW than other genotypes, suggesting that 6-SFT-D and 6-SFT-A2 have cumulative effect on TGW improvement.

Phenotypic Diversity Evaluations of Foxtail Millet Core Collections

WANG Hai-Gang,JIA Guan-Qing,ZHI Hui,WEN Qi-Fen,DONG Jun-Li,CHEN Ling,WANG Jun-Jie,CAO Xiao-Ning,LIU Si-Chen,WANG Lun,QIAO Zhi-Jun,DIAO Xian-Min

Acta Agron Sin. 2016, 42(01):  19-30.  doi:10.3724/SP.J.1006.2016.00019

Abstract ( 1456 )   RICH HTML    PDF (829KB) ( 2334 )   Save

References | Related Articles | Metrics

Evaluation of genetic diversity could benefit the identification of optimal parental combinations for obtaining segregating offspring with maximum genetic variability, and facilitate the introgression of favorable genes from various germplasm into commercial cultivars. In this study, foxtail millet core collections including 878 world-wide accessions were evaluated through phenotypic analysis of 15 agronomic traits. Main conclusions are as follows: (1) Chinese accessions present higher level of phenotypic diversity, especially in grain weight per main stem, panicle length, panicle diameter, plant height, stem node number and growth period; phenotypic diversity is lower in elite cultivars than in traditional landraces；gains of breeding progress in foxtail millet are expressed in reduced plant height and panicle length, coupling with increased diameter of main stem, stem node number, panicle diameter, grain weight per main stem, panicle weight per main stem and growth period; (2)from the cluster analysis, foreign resources are divided into three categories according to the geographical origins, the first category mainly includes accessions from northeast European countries, the second cluster is mainly collected from North America and Africa, and the third group includes varieties mainly from East Asia, South Asia, African, and European countries; Chinese collections is able to be divided into three groups of spring-sowing, summer-sowing and southern ecotypes; (3) comprehensive assessment of phenotypic traits based on principal component analysis (PCA) and step regression analysis demonstrates that leaf sheath color, bristle length, hull color, grain color, plant height, spike length, stem diameter and grain weight per plant can be used as main identification indicators of foxtail millet phenotypic variations. This research will benefit the utilization of foxtail millet resources in variety breeding practices in the future.

Evaluation of Improvement Effect of Restorer Lines on Pyramiding Genes Resistant to Rice Blast, Bacterial Leaf Blight and Brown Planthopper

LOU Jue,YANG Wen-Qing,LI Zhong-Xing,LUO Tian-Kuan,XIE Yong-Chu,ZHENG Guo-Chu,YUE Gao-Hong,XU Jian-Long,LU Hua-Jin

Acta Agron Sin. 2016, 42(01):  31-42.  doi:10.3724/SP.J.1006.2016.00031

Abstract ( 725 )   RICH HTML    PDF (1957KB) ( 1606 )   Save

References | Related Articles | Metrics

The novel blast resistance genes, Pi-GD-1(t) and Pi-GD-2(t) (abbreviated as G1 and G2, respectively) from rice cultivar Sanhuangzhan2, bacterial blight resistance gene Xa23 (abbreviated as X) from CBB23 and brown planthopper resistance gene Bph18(t) (abbreviated as B) from IR65482-7-216-1-2-B (abbreviated as IR65482) were introgressed into three rice restorer lines, Wenhui 845, Wenhui 117 and Wenhui 143, by marker-assisted backcross and pyramiding breeding methods integrated with artificial inoculation, natural induction and phenotypic selections. The eight resistant restorer lines pyramiding blast and brown planthopper resistance genes, i.e. Wenhui 845-G1-G2-B-4, Wenhui 845-G1-G2-B-5, Wenhui 117-G1-G2-X-B-3, Wenhui 143-G1-G2-B-3, Wenhui 143-G2-X-B-9, Wenhui 143-G2-X-B-10, Wenhui 143-G1-G2-B-11, and Wenhui 143-G1-G2-B-37, and their tester lines crossed with the sterile line Wufeng A demonstrated the similar or slight lower level of resistance against rice blast and brown planthopper as compared with the resistant donor parents Sanhuangzhan2 or IR65482. Part of developed restorer lines (Wenhui 117-G1-G2-X-B-3, Wenhui 143-G2-X-B-9 and Wenhui 143-G2-X-B-10) and their tester lines showed resistance or moderate resistance to bacterial blight. The newly developed restorers resistant to blast, bacterial blight and brown planthopper were similar or superior to their respective original types in agronomic traits under normal condition, implying these resistant restorer lines can be useful in hybrid rice breeding and production. The results indicated that Xa23 could completely express its dominant resistance against different restorer genetic backgrounds whereas effects of resistance improvement in Pi-GD-1(t), Pi-GD-2(t), and Bph18(t) depend on their genetic background.

Design of Test Location Number and Replicate Frequency in the Regional Cotton Variety Trials in China

XU Nai-Yin,JIN Shi-Qiao,LI Jian

Acta Agron Sin. 2016, 42(01):  43-50.  doi:10.3724/SP.J.1006.2016.00043

Abstract ( 822 )   RICH HTML    PDF (346KB) ( 988 )   Save

References | Related Articles | Metrics

The test location number and the replicate frequency in regional crop trials are important factors in determining both the trial heritability and cultivar selection efficiency. The test location number and replicate frequency for three national cotton regional trials in China were studied using experimental data during the last 15 years according to changes of trial heritability with the increase of test locations and replicates within trials in 2000–2014. The results indicated that three replicates are sufficient to achieve 0.75 of within-trial heritability. The current test locations in the Yangtze River Valley, the Yellow River Valley and the Northwest Inland regions are sufficient to achieve 0.75 of cross-trial heritability. Considering the importance of the regional trials in recommending cotton varieties and the possible trial cancellation due to poor field managements, natural disasters or other non-artificial factors, the optimum number of test locations proposed for the Yangtze River Valley should be maintained at the current level of 20 locations with H = 0.90 to ensure the enough credibility of regional trials, while that proposed for the Yellow River Valley and the Northwest Inland cotton regions should be increased to 27 and 19 locations with heritability level of 0.90 and 0.85, respectively. The conclusion will provide a theoretical guidance for the optimal configuration of national cotton regional trials and also act as a reference for the rational layout of regional trials in other crops.

Regulation of DTA-6 by Abscission Cellulase and GmAC Gene Expression in Flowers and Pods of Soybean

CUI Hong-Qiu,FENG Nai-Jie,SUN Fu-Dong,LIU Tao,LI Jian-Ying,DU Ji-Dao,HAN Yi-Qiang,ZHEN Dian-Feng

Acta Agron Sin. 2016, 42(01):  51-57.  doi:10.3724/SP.J.1006.2016.00051

Abstract ( 776 )   RICH HTML    PDF (368KB) ( 2351 )   Save

References | Related Articles | Metrics

It is effective to regulate abscission of soybean flowers and pods by spraying plant growth regulators (PGRs). This study was carried out to determine the effect of DTA-6 on abscission cellulose (AC) activity, abscission cellulose (GmAC) gene expressive, abscission of flowers and pods and yield in soybean. DTA-6 was foliage sprayed at R1 stage on three varieties of Suinong 28 (SN28), Kenfeng 16 (KF16), and Hefeng 50 (HF50) in 2012 and 2013. Our results demonstrated that DTA-6 treatment inhibited GmAC gene expression in abscission zone of flower and pod, with the maximum reduction of 51% among three varieties compared with control. The abscission cellulase activity was periodically decreased by DTA-6, with different decrements among soybean cultivars. DTA-6 significantly decreased (P<0.05) abscission rate of soybean flowers and pods. And significantly increased yield (P<0.05). The relative expression of abscission cellulase gene (GmAC) in abscission zone of flowers-pods was decreased and AC activity was regulated by DTA-6, resulting in reduced abscission rate of soybean flowers and pods and promoted yield.

Cloning and Expression Analysis of Auxin Efflux Carrier Gene CsPIN3 in Tea Plant (Camellia sinensis)

WANG Bo,CAO Hong-Li,HUANG Yu-Ting,HU Yu-Rong,QIAN Wen-Jun,HAO Xin-Yuan, WANG Lu,YANG Ya-Jun,WANG Xin-Chao

Acta Agron Sin. 2016, 42(01):  58-69.  doi:10.3724/SP.J.1006.2016.00058

Abstract ( 750 )   RICH HTML    PDF (5431KB) ( 1734 )   Save

References | Related Articles | Metrics

On the basis of previous transcriptome study on tea plant cold acclimatization, we obtained a PIN homology gene named CsPIN3 and cloned its full-length cDNA sequence by reverse transcription-PCR (RT-PCR) combining with rapid amplification of cDNA ends (RACE). The full length cDNA of CsPIN3 was 2654 bp (GenBank accession No. KP896474) and contained a 1 926 bp open reading frame (ORF) encoding 641 amino acid residues. Bioinformatic analyses showed that CsPIN3 was not a secretory protein and had a molecular weight of 70.15 kD, atheoretical isoelectric point of 8.42. Subcellular localization prediction showed that CsPIN3 was a typical membrane protein mainly located in plasmalemma and then in endoplasmic reticulum. Moreover, Amino acid sequence analysis indicated that CsPIN3 protein contained hydrophobic regions in both ends and hydrophilic regions in the middle. Similar to PIN protein in rice, the hydrophobic regions of CsPIN3 consisted of several transmembrane helixes, among which five was in N motif and four in C motif. The hydrophilic regions of CsPIN3 had two unstable domains, several o-glycosylation sites, several phosphorylation sites like TPRXS (N/S) motif (a PID/PINOID phosphorylation site) and a well characterized conserved inner motif NPNXY regulating the endocytosis of PIN. Comparison of sequences similarity showed that the amino acid sequence coded by CsPIN3 had more than 80% similarity with reported PINs of Populus trichocarpa, Vitis vinifera, Citrus sinensis, Nicotiana tomentosiformis, Solanum lycopersicum, Solanum tuberosum, and Sesamum indicum. Phylogenetic tree analysis showed that CsPIN3 had the closest genetic relationship with Solanaceae and the highest identity with AtPIN3 of Arabidopsis thaliana PIN proteins. The CsPIN3 gene differentially expressed in different tea plant tissues, and transcript abundance in flower was much higher than that in leaf, stem and root. In addition, we analyzed the expression of CsPIN3 by qRT-PCR during the different phases of bud dormancy formation and break, and the results indicated that in cultivar Longjing 43, the expression level of CsPIN3 at growth stage was higher than that at dormant stage (initial dormant stage to expanding stage) and an obvious expression jump was detected at bud sprouting stage. These demonstrated that CsPIN3 could be associated with the regulation of tea plant bud dormancy formation and break.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Comparison of Starch Granule Morphology and Size Distribution in Superior and Inferior Grains of Three Cereal Crops

XU Yun-Ji,LI Yin-Yin,QIAN Xi-Yang,WANG Zhi-Qin,YANG Jian-Chang

Acta Agron Sin. 2016, 42(01):  70-81. 

Abstract ( 1221 )   RICH HTML    PDF (3286KB) ( 1608 )   Save

References | Related Articles | Metrics

Using two rice cultivars, two wheat cultivars, and two maize cultivars, we extracted starch granules to observe the morphological characteristics and to compare the differences in the starch granule number, volume and surface area distributions among the three crops and between superior and inferior grains of each cultivar. The results showed that significant differences were observed in starch granule morphology and size among the three crops. The diameter of starch granule showed an order of maize > wheat > rice. Starch granules extracted in rice showed an irregular shape, the starch granules in wheat were lenticular-shaped and spherical-shaped. The starch granules in maize grain were mainly polyhedral or irregular and spherical in shape. Distributions of starch granule number, volume and surface area were changed in a typical unimodal-peak curve, a triple-peak curve and a typical bimodal-peak curve, respectively, in grains of rice and maize. Distributions of starch granule number, volume and surface area in wheat grains displayed a typical unimodal-peak curve, a four-peak curve and a triple-peak curve, respectively. According to starch granule diameters, all the starch granules were classified into small, medium, and large granules in this study. The thresholds for separating the starch granules were 1.5 μm and 20.0 μm, 5.0 μm and 50.0 μm, 4.0 μm and 50.0 μm, respectively, in rice, wheat and maize. The total volume of starch granules in grains of the three cereal crops was mainly determined by the volume of medium starch granules. No significant difference was observed in the proportions of small starch granule size and medium starch granule number between superior and inferior grains of the three cereal crops. But the volume and surface area of medium starch granules were larger in superior grains than in inferior ones. The percentage of large starch granules was greater in the inferior than in the superior. Changes in the volume of medium starch granules in both superior and inferior grains were consistent with those in starch accumulation and grain weight. The results suggest that the starch granule volume is an important factor determining grain weight. Increasing the volume of medium starch granules or reducing the volume of large starch granules would increase the weight of inferior grains.

Analysis and Simulation of Impact of Light and Temperature on Rice Tillering

WANG Meng-Meng,YANG Shen-Bin,JIANG Xiao-Dong,WANG Ying-Ping,CHEN De,HUANG Wei,YU Geng-Kang,SHI Chun-Lin

Acta Agron Sin. 2016, 42(01):  82-92.  doi:10.3724/SP.J.1006.2016.00082

Abstract ( 849 )   RICH HTML    PDF (636KB) ( 1491 )   Save

References | Related Articles | Metrics

In order to investigate the effects of light and temperature on rice tillering dynamics in tillering stage and validate the light and temperature effect equation in current dynamic tillering models. We performed two-year field-seeding experiments (2012–2013) using two indica two-line hybrid rice cultivars, Lingliangyou 268 and Liangyoupeijiu. And we collected the observation data in tillering. To fit Richards equation for retrieving characteristic parameters related to the maximum tiller density, average growth rate of tillers, and duration of the growing period. Moreover, we analyzed the relationships between all these characteristic parameters and average data of light, temperature and climatic variables during the growing period for each rice cultivar. Based on the relationships we established co-effect equations for the growth rate of tillers and maximum tiller density as a function of co-effect of light and temperature. The new co-effect functions for each cultivar were substituted for the effect functions of light and temperature in a widely used dynamic tillering model to simulate the dynamic tillering in tillering stage. Finally, validation and comparison were carried out for the models applied observation data in tillers period. The result showed that the light and temperature affected crop growth in tillering period. The growth rate of tillers and the actual maximum tiller density positively correlated with the two meteorological factors significantly. Compared with current dynamic tillering model, the model with the established co-effects of light and temperature functions decreased the error significantly in simulating the growth dynamics of tillers. The simulated rice tillering was well consistent with the observed in both growth rate and maximum tiller density for both rice cultivars. However, the discrepancy could also be found in some seeding periods and validation samples, which may be caused by rice adaptability to different light and temperature environments. In conclusion, the validation and improvement of the light and temperature co-effect functions put forward in this study can be used further for understanding the effects of light and temperature factors on rice tillering and improving dynamic tillering models in the future.

Effects of Seed Dressing with Uniconazole Powder on Lodging Resistance of Culm in Common Buckwheat

LIU Xing-Bei，WANG Can,HU Dan,YANG Hao,SHE Heng-Zhi,RUAN Ren-Wu,WU Dong-Qian,YI Ze-Lin

Acta Agron Sin. 2016, 42(01):  93-103.  doi:10.3724/SP.J.1006.2016.00093

Abstract ( 645 )   RICH HTML    PDF (649KB) ( 1269 )   Save

References | Related Articles | Metrics

Lodging is one of the important factors affecting the yield and quality of common buckwheat (Fagopyrum esculentum M.) worldwide. Ningqiao 1, a cultivar of common buckwheat with moderate lodging resistance was used in this study to investigate the dynamic changes of lodging behavior, yield, culm snapping resistance, lodging index, culm morphological characteristics and culm anatomical structure seed dressing with uniconazole powder(0, 100, 200, and 300 mg kg^-1). The results indicated that seed dressing with uniconazole powder had significantly effects on the lodging resistance of culm in common buckwheat. With the increase of uniconazole powder concentration, the yield, culm snapping resistance, diameter of the 2nd internode, dry weight of the 2nd internode, filling degree, mechanical tissue layer number, mechanical tissue thickness, culm wall thickness, vascular bundle number, and vascular bundle area showed an increased-decreased trend, whereas, the lodging percentage, lodging index, plant height, culm gravity height, culm fresh weight, and length of the 2nd internode showed an decreased-increased trend. In this case, the treatment of seed dressing with 200mg kg^-1 uniconazole powder could optimize the culm structure, improve the culm quality, reduce the lodging risk, and enhance the yield of common buckwheat.

Effects of Different Row Spaces on Canopy Structure and Resistance of Summer Maize

CHANG Jian-Feng,ZHANG Hai-Hong,LI Hong-Ping，DONG Peng-Fei,LI Chao-Hai

Acta Agron Sin. 2016, 42(01):  104-112.  doi:10.3724/SP.J.1006.2016.00104

Abstract ( 1123 )   RICH HTML    PDF (240KB) ( 2038 )   Save

References | Related Articles | Metrics

In order to explore the effects of row spacing on canopy structure and stress resistance, and identify the appropriate row spacing suitable for the development of agricultural mechanization, field experiments were conducted at Fangcheng and Huixian, using three types of maize hybrids (Xianyu 335 is a high plant, Zhengdan 958 is a middle high plant, and 512-4 is a dwarf) with two plant population densities (60 000 and 75 000 plant ha^-1) and five row spaces (50 cm, 60 cm, 70 cm, 80 cm, and 80 cm+40 cm). The results showed that, for treatments with equal rows spacing under the same plant density, with the increasing of row spaces, different hybrids had a leave type and decreased leaf orientation value (LOV), their growth deviated from the plant rows, and trend to perpendicular to row; canopy temperature and humidity decreased, light interception and yield were reduced as well, while resistance to disease and insect was improved. The treatments with 60 cm row spacing can reasonably coordinate the relationship between the canopy microenvironment and yield, resulting in appropriate distribution of canopy leaves, suitable canopy temperature and humidity, maize light interception, especially, with the high light interception rate in the lower part of the canopy, and the significantly increased resistance to stresses, different hybrids with two densities got highest yield frequently in treatments with 60 cm of row spacing regardless of the varieties with different plant heights at planting densities, which so suitable for mechanical farming and field management. Therefore, we suggest that 60 cm is the optimal row spacing for summer corn in Huanghuaihai Region.

Effects of Nitrogen Application Rates on Root Yield and Nitrogen Utilization in Different Purple Sweetpotato Varieties

WU Chun-Hong,LIU Qing,KONG Fan-Mei,LI Huan,SHI Yan-Xi

Acta Agron Sin. 2016, 42(01):  113-122.  doi:10.3724/SP.J.1006.2016.00113

Abstract ( 986 )   RICH HTML    PDF (242KB) ( 1544 )   Save

References | Related Articles | Metrics

A two-year field experiment was conducted in the Modern Agricultural Science and Technology Demonstration Garden of Qingdao Agricultural University in 2013 and 2014. Three varieties of purple sweetpotato (Zhezi 1, Ningzi 2, and Zijing 2) were grown with three nitrogen rates (0, 75, and 150 kg·ha^–1 as N0, N1, N2 treatment, respectively). The storage root yield, dry matter accumulation rate, nitrogen accumulation amount and N use efficiency of the purple sweetpotato were investigated under the three N levels. The results showed that the storage root yields of Zhezi 1 and Zijing 2 in N1 and N2 treatments reduced to a varying degree compared with N0 treatment, with the decrease of 12.64% and 13.32% for Zhezi 1 and 3.94% and 29.06% for Zijing 2, respectively. Meanwhile, the storage root yield of Ningzi 2 in N1 treatment slightly increased by 8.5% and 3.4% in 2013 and 2014, respectively, compared with N0 treatment, but significantly decreased in N2 treatment compared with both N0 and N1 treatments. Compared with N0 treatment, the shoot biomass increased from 2.7% to 20% in N1 and from 12.3% to 36.4% in N2, in 2013, as well as from 12.6% to 51.9% in N1 and from 28.7% to 85.5% in N2, in 2014. However, the harvest index, N harvest index and nitrogen use efficiency gradually reduced with the increase N application. The correlation analysis showed that the root yield positively correlated with all the nitrogen efficiency parameters, however the shoot biomass negatively correlated with the harvest index, nitrogen harvest index and nitrogen utilization efficiency (r = 0.615^**, 0.704^**, 0.663^**). The shoot biomass of Zhezi 1 and Zijing 2 increased with the increase of N application, showing the decrease of photosynthate from shoots to roots. The nitrogen demand of Ningzi 2 was higher than other two varieties, and the moderate nitrogen application could increase the root yield in fertile soil. In conclusion, the coordinated growth of shoots and roots is important for improving storage root yield and N use efficiency.

Effects of Sowing Date, Density and Nitrogen Application Amount on Nitrogen Utilization Rate of Guangmingmai 1 Grown in Rice–Wheat System

XU Hui,CUI Huai-Yang,ZHANG Wei,DING Jin-Feng,LI Chun-Yan,GUO Wen-Shan,ZHU Xin-Kai

Acta Agron Sin. 2016, 42(01):  123-130.  doi:10.3724/SP.J.1006.2016.00123

Abstract ( 844 )   RICH HTML    PDF (643KB) ( 1469 )   Save

References | Related Articles | Metrics

Improvement of utilization rate of nitrogen fertilizer (NUR) is one of research focuses in wheat. In a two-year field experiment, the NUR of wheat variety Guangmingmai 1 in the wheat–rice rotation system in response to sowing date (S), density (D), and nitrogen application rate (N) was studied using a mathematical model based on quadratic regression rotation-orthogonal combination design. Among the three factors, nitrogen application rate had the greatest effects on NUR, followed by sowing date and density. Several S+D+N combinations resulted in high yield and high NUR under the experimental conditions. The highest yield level (6800–7200 kg ha^–1) was obtained in the combination of S between October 28 and November 2, D between 1.6 and 1.8 million plants per hectare, and N at 200 kg ha^–1. Simultaneously, the NUR was higher than 42.0% (the maximum was 44.8%) with a credibility larger than 95%. At the yield level of 6200–7000 kg ha^–1 and NUR higher than 41.0%, the optimal S, D and N were 21–27 October, 1.2–1.5 million plants per hectare and 190–225 kg ha^–1, respectively. At the yield level of 5900–7250 kg ha^–1 and NUR higher than 39.0%, the agronomic practices were recommended to be S between November 3 and November 11, D between 2.1 and 2.4 million plants per hectare, and N between 190 and 210 kg ha^–1.

Comparison of Root Characteristics and Sugar Components in Root and Leaf at Early Growth Phase of Sweet Potato Varieties with Significant Difference in Valid Storage Root Number

WANG Cui-Juan,SHI Chun-Yu,LIU Na,LIU Shuang-Rong,YU Xin-Di

Acta Agron Sin. 2016, 42(01):  131-140.  doi:10.3724/SP.J.1006.2016.00131

Abstract ( 899 )   RICH HTML    PDF (413KB) ( 1489 )   Save

References | Related Articles | Metrics

Starch sweet potato varieties Shangshu 19 and Jixu 23 differing in valid storage root number per plant significantly were used to investigate root characteristics, sugar components in root and leaf at early growth phase and their relationship with the formation of storage root per plant at top cover stage. The results showed that, Shangshu19 with higher valid storage root number regrew quickly with more new roots after seedling transplanting, developed fiberous roots mainly in the whole early growth phase, and formed a stable rate of top biomass/total root system biomass (T/TR) at 15 and 30 days after planting. Jixu 23 achieved the steady number of adventitious root and valid storage root at 15 and 30 days after planting, respectively. Meanwhile, Jixu 23 showed the lower rate of top biomass/storage root biomass (T/SR) at top cover stage (45 days after planting). On the other hand, in point of metabolism of sucrose and hexoses, and the formation of stored polysaccharide polymers, Shangshu19 had significantly lower rate of sucrose/hexoses in the whole early growth phase, formed the greater sucrose concentration gradient between leaves and roots, and had 1-Kestose and Nystose in roots at 15 and 30 days after planting. Its starch content in leaf was significantly lower than that of Jixu 23 at 30 and 45 days after planting. Meanwhile, Jixu 23 only had Nystose in roots before storage root formation, with significantly lowest rate of sucrose/starch when the rate of sucrose/total soluble sugar was similar to that of Shangshu 19 at 45 days after planting. A two-year field trials (2013–2014) were performed to investigate yield-contributing traits and the fresh storage root yield at top cover stage and harvest period, in which, Shangshu19 showed the more valid storage roots per plant, higher valid storage root fresh weight per plant or storage root at top cover stage and harvest period, meanwhile, Jixu23 had significantly higher average fresh weight per storage root.

RESEARCH NOTES

A New Algorithm for Conformity and Its Application

ZHANG Hui,GU Shi-Liang,LI Tao

Acta Agron Sin. 2016, 42(01):  141-148.  doi:10.3724/SP.J.1006.2016.00141

Abstract ( 759 )   RICH HTML    PDF (1280KB) ( 1633 )   Save

References | Related Articles | Metrics

This article proposed a new algorithm of conformity using original data to calculate similarities between the target object and the expected value based on the Mahalanobis distance, providing an objective and reasonable analysis. Firstly, simulation experiments were conducted to obtain Mahalanobis distance (d) related to number (p) of different variables (traits) and similarity (r). Then, a surface fitting method was used to establish the function relationship between conformity (r) and index number (p), as well as Mahalanobis distance (d). Monte Carlo experiment for frequency distribution of conformity verified its good performance of the relationship model. The simulation results fully validated the feasibility and reliability of the model. Conformity algorithm was applied to calculating the similarity of a panel of Yangmai wheat varieties released in recent years referring to RVA parameters. The assessment of simulated multivariate regression for complex effects was also conducted. This study showed that conformity algorithm using raw data directly instead of standardized data reduces the work load and decreases inconsistency in similarity assessment with different data processing methods. In addition, conformity algorithm does not need weight assignment to each trait, thus can eliminate potential subjective impacts on traits or data and guarantee integrity of information and reliability of evaluation results.

Yield in Response to Accumulated Temperature before Winter in Winter Wheat

Lü Li-Hua,LIANG Shuang-Bo,ZHANG Li-Hua,JIA Xiu-Ling,DONG Zhi-Qiang,YAO Yan-Rong

Acta Agron Sin. 2016, 42(01):  149-156.  doi:10.3724/SP.J.1006.2016.00149

Abstract ( 1001 )   RICH HTML    PDF (410KB) ( 2161 )   Save

References | Related Articles | Metrics

The purposes of this study were to recommend optimal sowing dates of commercial wheat cultivars in middle part of Hebei province, China and screen out wheat cultivars acclimatized to late sowing. A field experiment was carried out with split plot design (main plot of sowing date and subplot of cultivar) in Gaocheng of Hebei province from Autumn 2011 to Summer 2014 to evaluate the effect of sowing date on 12 major cultivars and the response of cultivars to accumulated temperature before winter. The results showed that sowing date had significant influence on grain yield, and the 12 cultivars had different responses to sowing date. According to yield changing rate subject to late sowing, the 12 cultivars were classified into insensitive, intermediate, and sensitive types. Insensitive cultivars showed stable spike number and yield under late sowing condition, indicating a wide range of preferred sowing date. The desired accumulated temperature before winter was 324–560 °C. Intermediate cultivars also had a long period of sowing date with 362–566 °C before winter. Late sowing resulted in the increase of grain number but the decreases of spike number and yield in intermediate cultivars. Sensitive type had a narrow range of sowing date and was not suitable for late sowing, because at least 511 °C before winter was required. Late sowing resulted in obvious declines of spike number and yield in sensitive cultivars. In the middle part of Hebei province, we recommend that the optimal sowing time in wheat production is Oct. 7–22 for insensitive cultivars, Oct. 7–19 for intermediate cultivars, and Oct. 5–10 for insensitive cultivars.