Table of Content

12 August 2010, Volume 36 Issue 08

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ORIGINAL PAPERS

My Humble Opinions on High Photosynthetic Efficiency of Crop

CHENG Jian-Feng, CHEN Yun-Gang

Acta Agron Sin. 2010, 36(08):  1235-1247.  doi:10.3724/SP.J.1006.2010.01235

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Photosynthesis provides the material basis of crop yield formation. At present, crop biomass yield must be enhanced if crop yield is expected to be more improved under the conditions of more difficultly increasing crop leaf area index and economic coefficient, the key approach is improving solar radiation utilization efficiency. High photosynthetic efficiency of crop is a concept with widely connotation and extension; it involves in the whole process of crop life activities and relates to many subjects with different views. At the basis of current research progress, combined with author’s practice in crop physiology, breeding and cultivation, we outlined high photosynthetic efficiency of crop from the major process and critical control points of photosynthesis, solar radiation utilization efficiency, the physiological basis, morphological characteristics, identification and screening of crop with high photosynthetic efficiency to provide some beneficial thoughts and references for the future research.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

A Genetic Analysis Method of Major-Minor Locus Groups in diallel Cross Design

HE Jian-Bo,GUAN Rong-Zhan,GAI Jun-Yi

Acta Agron Sin. 2010, 36(08):  1248-1257.  doi:10.3724/SP.J.1006.2010.01248

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Studies on inheritance of quantitative traits are usually based on two-way crosses, while in plant breeding, knowledge on inheritance of traits among a group of parental materials is needed since elite genes or QTLs are scattered in different materials. It is especially true in breeding for hybrids. Based on our previous studies on major locus group analysis among a set of parents, we aimed at extending the analysis to major-minor locus groups in diallel cross experiment. The statistical method was derived from a forward stepwise regression for identifying major locus groups and estimating their genetic effects as well as the estimation of genetic effect of collective minor locus groups. In which the procedure of adjusting F criterion was raised since biased F-test was found in a simulation study. Then the procedure was used to evaluate the relationship between its power and some factors, including heritability value, number of major locus groups, genotypic frequency with increment alleles, similarity among major locus groups and effect of collective minor locus groups. A simulated diallel cross experiment was used to demonstrate the effectiveness of the procedure. A diallel cross experiment on days to flowering of rapeseed was given to show the statistical steps and its utilization. The procedure of major-minor locus group analysis in diallel crosses based on major gene plus polygene inheritance model provides a way to analyze the genetic constitution of a group of parental materials for obtaining the best hybrid combinations.

Screening of Rice Resources against Rice Black-Streaked Dwarf Virus and Mapping of Resistant QTL

WANG Bao-Xiang, JIANG Ling, CHEN Liang-Ming, LU Bai-Guan, WANG Qi, LI Guang-Quan, FAN Ji-Wei, CHENG Xia-Nian, ZHAI Hu-Qu, XU Da-Yong, WAN Jian-Min

Acta Agron Sin. 2010, 36(08):  1258-1264.  doi:10.3724/SP.J.1006.2010.01258

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Rice black-streaked dwarf virus(RBSDV)disease become epidemic in Jiangsu and Zhejiang provinces. To screen resistant germplasms and discover new resistance genes/QTLs against RBSDV, we evaluated the resistance to RBSDV in 311 japonica cultivars in field test. The results showed that no cultivar was immune to RBSDV. The disease rate of 24 main japonica cultivars grown in Jiangsu province at present was 10.0%–29.0% and that of 71.5% cultivars in 287 japonicapopularized in Jiangsu beforewas between 10.0% and 30.0%. Furthermore, quantitative trait loci (QTL) analysis was conducted by using 162 recombinant inbred lines (RILs), which derived from a cross between Guichao 2, a susceptible indica variety, and Koshihikari, a japonica variety with resistance to RBSDV. RBSDV resistances were evaluated using natural infection methods by scoring the disease rating. One putative QTL (qRBSDV3) controlling RBSDV resistance was mapped between the marker RM7 and RM5748 on chromosome 3, which explained 17.1% of the total phenotypic variation with LOD score of 5.4. The positive resistant effect contributed from Koshihikari. Further analysis revealed that the lines harboring the alleles of qRBSDV3 exhibited significantly increased resistance to RBSDV. The results should be very useful for breeding new RBSDV-resistant cultivars by marker-assisted selection (MAS). cultivars

Molecular Mapping of Leaf Rust Resistance Genes in Wheat Line Tian 95HF2

ZHOU Yue, WANG Long, ZHANG Ye, LI Zai-Feng, LIU Da-Qun

Acta Agron Sin. 2010, 36(08):  1265-1269.  doi:10.3724/SP.J.1006.2010.01265

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The wheat (Triticum aestivum L.) line Tian 95HF2 appears in low infection to most of Chinese current pathotypes of Puccinia triticina at seedling stage. For postulating the resistance genes in Tian 95HF2, F₁ and F₂ populations from the cross between Tian 95HF2 and Zhengzhou 5389 (susceptible to leaf rust) were inoculated with pathotypes FHTT and PHTS in greenhouse. The infection types were investigated 15 d after inoculation and molecular markers were also used for mapping the resistance genes. When inoculating with pathotype FHTT, only one resistance gene was detected. After screening 1274 primer pairs in the parents and the resistant and susceptible bulks, the resistance gene was found between the interval of a sequence tag site for Lr1 (WR003) and a microsatellite (wmc443) on 5DL.The genetic distances to the two markers were 2.9 cM and 3.1 cM, respectively. This resistance gene was finally postulated to be Lr1. The segregation of infection type in response to pathotype PHTS showed that there were two resistance genes in Tian 95HF2. One was inferred as Lr1, and the other was likely to be LrZH84, which is located on chromosome 1BL.

Screening Marker Genotypes with Elite Combining Ability for Yield Traits in Parents of Hybrid Japonica Rice (Oryza sativa L.)

LIANG Kui, HUANG Dian-Cheng, ZHAO Kai-Ming, RUAN Fang-Song, XIE Hui, MA Wen-Xia, HONG De-Lin

Acta Agron Sin. 2010, 36(08):  1270-1279.  doi:10.3724/SP.J.1006.2010.01270

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The area of japonica rice planted annually is 8 280 000 ha and accounts for 27% of total rice area in China. The area planting japonica hybrid rice is only 3% of the total area of japonica rice. The major reason for this situation is that competitive heterosis of hybrid cultivar is not conspicuous in yield, compared with conventional cultivar in japonica rice. The key factor of enhancing competitive heterosis of hybrid cultivar in japonica rice is to improve combining ability of yield related traits of restorer lines. In order to improve combining ability of restorer lines more efficiently, SSR marker genotypes with elite combining ability for five traits were screened in this study, by analyzing the data of combining ability and SSR markers in six CMS lines and twelve restorer lines that were genotyped using 115 pairs of SSR primers. Combining ability of the 18 parental lines was analyzed for daily yield per plant (DYP), panicles per plant (PP), total spikelets per panicle (TSP), filled spikelets per panicle (FSP) and 1000-grain weight (1000-GW), using the data of 72 F₁s made with NC II genetic design. Results showed that twenty SSR marker genotypes were significantly associated with combining ability of the five traits. Among them, eight for only one trait, six for two traits, four for three traits and two for four traits. Marker genotypes associated with combining ability of multiple traits increased or decreased trait value of F₁. RM152-165/170 was a marker genotype of elite combining ability for PP and DYP with the maximum increasing effect, which increased 20.6% of DYP and 12.7% of PP in F₁ respectively. Those marker genotypes with increasing effect could be directly used to improve combining ability of restorer lines through the marker- assistant selection.

Resynthesis of Brassica napus with Brassica oleracea or Brassica rapa Cytoplasm

LI Jun, LUO Li-Xia, WANG Zhuai, LI Jun, CHEN Kun-Rong, REN Li, FANG Xiao-Ping

Acta Agron Sin. 2010, 36(08):  1280-1285.  doi:10.3724/SP.J.1006.2010.01280

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Nuclear genome is the primary genetic material, which plays a key role in the individual development and the system evolution of plant. Although relatively independent genetic system in cytoplasm is existed, the characteristics of plant is more often determined by the nuclear genes and sometimes affected by plasmagenes. To compare genetic effect of different plasmagenes of B. napus and study interactions between nuclear gene and cytogene, we artificially synthesized B. napus with B. oleracea or B. rapa cytoplasm by means of hybrid embryo and ovary culture of reciprocal crosses between 12 cultivated varieties of B. rapa and one cultivated variety of B. oleracea var. alboglabra.The average frequencies of hybrid plantlets obtained were 2.32% from ovary culture of B. rapa × B. oleracea var. alboglabra and 1.16% from embryo culture of B. oleracea var. alboglabra × B. rapa, respectively. The induction rate of hybrid plantlets differed greatly between different crosses, but the trends of induction easily or hardly were the same between reciprocal crosses with the same parents. The haploidic hybrid seedlings were pre-cultured in MS medium with 0.01% colchicine for 10 days which was the best way for chromosome doubling. The percentage of hybrid plantlets with doubled chromosomes was 59.32%. Agronomic traits of synthesized B. napus were similar to those of cultivated B. napus and mediated between parents in morphology, but more similar to maternal plants. The average pollen fertility for the most synthesized lines ranged from 40.53% to 88.95%.

Establishment of Molecular Linkage Maps Using SRAP Markers in Sweet potato

LI Ai-Xian, LIU Qiang-Chang, WANG Qiang-Mei, ZHANG Li-Ming, ZAI Hong, LIU Shu-Zhen

Acta Agron Sin. 2010, 36(08):  1286-1295.  doi:10.3724/SP.J.1006.2010.01286

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Sweet potato [Ipomoea batatas (L.) Lam.] is an important vegetative reproduction crop. Despite its worldwide importance, molecular biology researches in sweet potato have lagged behind other crops due to its characteristics including polyploidy, outcrossing behavior and high heterozygosity. As a result, it is difficult to make a breakthrough for the improvement of sweet potato using conventional methods. In this study, sequence-related amplified polymorphism (SRAP) markers were applied to establish molecular genetic linkage maps with F₁ population consisting of 240 individuals derived from a cross of sweet potato cv. Luoxushu 8 (high starch content cultivar) × cv. Zhengshu 20 (low starch content cultivar). A total of 770 and 523 SRAP markers were generated, respectively, in Luoxushu 8 and Zhengshu 20. Using the software of JoinMap 3.0 and the ‘double pseudo testcross strategy’, a molecular linkage map containing 81 linkage groups was established with 473 SRAP markers in Luoxushu 8, and the map covered 5 802.46 cM with an average marker interval of 10.16 cM. In Zhengshu 20，the molecular linkage map containing 66 linkage groups was constructed using 328 SRAP markers, and the map covered 3 967.90 cM with an average marker interval of 12.02 cM. The results will provide a powerful tool to facilitate the introgression of desired traits into cultivars, gene localization and map-based cloning techniques, and greatly increase breeding efficiency through marker-assisted selection (MAS) techniques.

Novel High Oil Germplasm with Resistance to Aspergillus flavus and Bacterial Wilt Developed from Recombinant Inbred Lines

LIAO Bo-Shou, LEI Yong, WANG Sheng-Yu, HUANG Jia-Quan, LIN Xiao-Peng, JIANG Hui-Fang, YAN Li-Ying

Acta Agron Sin. 2010, 36(08):  1296-1301.  doi:10.3724/SP.J.1006.2010.01296

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One of the important goals for peanut breeding in China is to enhance the resistance to aflatoxin accumulation and bacterial wilt (Ralstonia solanacearum) as well as to increase the oil content in peanut. In the present study, recombinant inbred lines were constructed with the offspring derived from Yuanza 9120 ´ Zhonghua 5. Yuanza 9120 with average oil content has high resistance to bacterial wilt but no resistance to aflatoxin accumulation; Zhonghua 5 is high yielding, high susceptible to bacterial wilt and not resistant to aflatoxin accumulation. Resistances to aflatoxining and bacterial wilt were identified in F_7-10 as well as the oil content and agronomic traits of lines were investigated. The results indicated that resistance to Aspergillus flavus was controlled accumulatively by two linked main genes and other additive genes, and oil content was controlled by two inhibitory main genes as well as other additive genes. There were significant difference for bacterial wilt resistance, resistance to Aspergillus flavus and oil content between the offspring and parents which presented heterobeltiosis. Eighteen high oil content lines with resistance to to Aspergillus flavus or bacterial wilt were obtained, one (J091) of which was resistant both to Aspergillus flavus and bacterial wilt. Analysis of agronomic traits and SSR data indicated that 18 lines were considerably diverse and may be used as potential breeding materials.

Molecular Marker-Assisted Selection for Corn o2 Introgression Lines with o16 Gene

ZHANG Wen-Long, YANG Wen-Peng, CHEN Zhi-Wei, WANG Ming-Chun, YANG Liu-Qi, CAI Yi-Lin

Acta Agron Sin. 2010, 36(08):  1302-1309.  doi:10.3724/SP.J.1006.2010.01302

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The opaque-2 (o2) mutant is commonly used as a donor to breed high lysine corn. But the highest lysine content of the o2 line as well as the resultant hybrids is about 0.4%. So, it is necessary to increase lysine content for the staple food consumed by human and animals. QCL3021 line carrying opaque-16 (o16) gene is another high lysine mutant. This study was performed to transfer o16 gene into o2 line through hybridization between QCL3021 (donor) and o2 line Taixi 19 (receiver) followed by multiple backcrossing. The foreground selection was performed using simple sequence repeats (SSR) marker umc1066 for o2 gene and umc1141 for o16 gene in every backcrossing and subsequent inbred generation. Selected plants were then screened for recovery of genetic background using SSR markers covering the whole genome. Grain lysine content was determined by dye-binding lysine (DBL) method. Plants with high lysine content and higher genetic background recovery ratio were eventually chosen. In BC₂F₄ generation, 17 family lines which carry both o2 and o16 genes were identified, with the genetic background recovery ratio of 92%–95%, indicating that the genome of these lines was highly identical with o2 corn line. Lysine content of the selected plants was 0.469%–0.599%, which was an average increase of 122.63% for normal corn,22.33% for the high parent line Taixi 19, and 65.86% for the low parent line QCL3021. This study demonstrated that molecular marker-assisted selection (MAS) for corn o2 introgression lines that were infiltrated with o16 gene was successful in improving grain lysine content. The established procedure can be applied in high lysine corn breeding and genetic improvement.

Mapping Grain Weight and Shape QTLs Using Four Sister Near Isogenic Lines (SNILs) of Rice (Oryza Sativa L.)

YAO Guo-Xin, LI Jin-Jie, ZHANG Qiang, HU An-Long, CHEN Chao, THANG Bo, ZHANG Hong-Liang, LI Zi-Chao

Acta Agron Sin. 2010, 36(08):  1310-1317.  doi:10.3724/SP.J.1006.2010.01310

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Grain weight (GW) is one of three major determinants of rice yield. In order to develop sister near isogenic lines (SNILs) for mapping GW and grain shape QTLs, we developed a cross with SLG-1 (as donor), one of the largest GW varieties in the world, and small GW variety Nipponbare(as recurrent), and selected larger GW plants to backcross with Nipponbare in different generations. Through analysis with total 73 BC₄F₁plants, we found four peaks in the frequency distribution of GW, and then selected four plants with the GW of each top peaks respectively to develop four SNIL populations. Using bulked segregant analysis(BSA), from 1 513 SSR makers evenly distributed on rice genome, we screened out 19 polymorphic SSR makers related to GW and grain shape. Using the LOD score 2.5 as the threshold, 12 QTLs for GW, grain length (GL), seed width (SW), and grain thickness (GT) were identified, which located on six regions of rice chromosome with explained phenotypic variation ranging from 7.22% to 53.38%. These QTL regions contained the cloned genes GS3 and GW2. Five GW and grain shape QTLs which were not be fine-mapped in previous research were also detected in the regions of RM6318–RM1367 on chromosome 2, RM5477–RM6417 on chromosome 3 and RM3370–RM1161 on chromosome 6. Among them, qGL3-1 with higher contribution was a new QTL for GL. The results provide a foundation for fine mapping and cloning new QTLs for GW and grain shape.

Mapping QTLs for Lint Percentage and Seed Index by Using Gossypium barbadense Chromosome Segment Introgression Lines

ZHU Ya-Juan, WANG Peng, GUO Wang-Zhen, ZHANG Tian-Zhen

Acta Agron Sin. 2010, 36(08):  1318-1323.  doi:10.3724/SP.J.1006.2010.01318

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Seed index (SI) and lint percentage (LP) are very important components, and many researchers have done abundant investigation on them by using different populations. Chromosome segment introgression lines (CSIL), different from the recurrent parent in introgressed segments, are the ideal materials for QTL research and the core of the breeding by design. The F₂ and F_2:3 populations were developed from CSILs-IL-15-5 and IL-15-5-1, and used in mapping QTLs for lint percentage and seed index with SSR markers. The SI and LP characteristics of the 774 F₂ individuals and F_2:3 families were analyzed by composite interval mapping (CIM), and one QTL was detected for SI and two QTLs for LP. qSI-15-1 was located between NAU2814 and NAU3040 with confident genetic distance of 6.70 cM in the F₂ population and between NAU3040 and JESPR152 with confident genetic distance of 5.70 cM in the F_2:3 population. qLP-15-1 detected in the F₂ and F_2:3 populations was located between NAU3040 and JESPR152 with confident genetic distance of 5.40 cM and 3.20 cM respectively; qLP-15-2 was mapped between NAU5302 and NAU2901 with confident genetic distance of 0.08 cM. In conclusion, the QTLs for yield components in cotton can be mapped using CSILs and provide a base for breeding by design.

Bioinformatic Prediction of MicroRNAs and Their Target Genes in Maize

ZHANG Zhi-Ming, SONG Rui, PENG Hua, LUO Mao, SHEN Ya-Ou, LIU Li, ZHAO Mao-Jun, PAN Guang-Tang

Acta Agron Sin. 2010, 36(08):  1324-1335.  doi:10.3724/SP.J.1006.2010.01324

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microRNAs (miRNAs) are an extensive class of endogenous, non-coding, short (19–24 nt) RNA molecules directly involved in regulating gene expression at the post-transcriptional level and played an important role in gene expression regulation. Previous reports have noted that plant miRNAs are highly conserved, which provides the foundation for identification of miRNAs in plant species through homology alignment. With the method of bioinformatic computation, all previously known miRNAs in Arabidopsis, rice, and other plant species were blasted against maize EST (expressed sequence tags) and GSS (genomic survey sequence) sequences to select novel miRNAs in maize by a series of filtering criteria. A total of 23 conserved miRNAs were identified and predicted the target genes by a web-based integrated computing system, WMD 3. Total of 89 miRNA targets were predicted and verified to be involved in maize growth and development, signal transduction, transcriptional regulation, metabolism, and stress responses.

Tissue Speciality and Stress Responses in Expression of Three WAX2 Homologous Genes in Rice

GAO Guo-Fu, ZOU Jie, ZHOU Xiao-Yun, LIU Ai-Ling, WEI Bao-Yang, CHEN Shen-Bo

Acta Agron Sin. 2010, 36(08):  1336-1341.  doi:10.3724/SP.J.1006.2010.01336

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Plant surface is covered by epidermis with a layer of wax. It can regulate non-stomatal water loss, protect against ultraviolet radiation damage and germ invasion. WAX2 gene in Arabidopsis is involved in cuticular wax production and significantly affects leaf water evaporation. Three WAX2 homologous genes in rice, named OsWAX2-1, OsWAX2-2, OsWAX2-3 were found by BLAST search in the NCBI database, with the homology of 56.0%, 55.2%, and 52.0% to Arabidopsis WAX2 gene respectively. Homology of their predicted proteins to Arabidopsis WAX2 protein was 61.5%, 60.5%, and 64.7%, respectively. All of the three proteins had four transmembrane domains and a conserved sterol desaturase domain, suggesting that OsWAX2 proteins are transmembrane proteins and may be related to plant cuticular wax biosynthesis. Expression patterns of the three rice WAX2 homologs were analyzed using semi-quantitative RT-PCR. The results showed that the three OsWAX2 genes had tissue speciality in expression. They also exhibited different expression patterns under high-temperature, low temperature, NaCl, PEG and ABA treatments. These results could be useful for further functional characterization of the three OsWAX2 genes.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Preliminary Study on Parameters of Precise and Quantitative Nitrogen Application in Rice Varieties with Different Growth Period Durations

YAN Chun-Yuan, ZHANG Hong-Cheng, ZHANG Qing, WEI Hai-Yan, DAI Qi-Gen, HE Zhong-Yang, XU Ke, MA Qun, LI Min, LI Guo-Ye

Acta Agron Sin. 2010, 36(08):  1342-1354.  doi:10.3724/SP.J.1006.2010.01342

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The objective of this study was to expose the change law of the three parameters of the precise and quantitative N application based on the Stanford equation in different growth types of rice. Three levels of N fertilizer application rates of 0, 225, and 300 kg ha⁻¹ N were designed in a field experiment with early (125–135 d), medium (136–145 d), late-maturing (146–155 d) medium japonica and early (156–165 d), medium-maturing (166–175 d) late japonica rice in 2007 and 2008 on the farm of Yangzhou university, Jiangsu province, China. The results were as follows: (1) Under zero N application, soil basal N application (N accumulation for basal yield) increased with the extension of the rice growth duration, in which the parameter of calculating N accumulation for basal yield was the N requirement for 100 kg grains. There were only small differences in N requirement for 100 kg grains between medium, late-maturing medium japonica and early-maturing late japonica rice. For an average yield of 6 t ha⁻¹ (4.87–6.58), the N requirement for 100 kg basal yield was 1.58 kg (1.50–1.63). (2) Under N application, the N requirements for 100 kg grains were rather stable in medium，late-maturing medium Japonica and early-maturing late Japonica rice. With the average yield of 7.5 t ha⁻¹, N requirement for 100 kg grains was 1.86 kg (1.85–1.87) under 225 kg ha⁻¹ N level and 2.01 kg (1.98–2.05) under 300 kg ha⁻¹ N level, respectively. With the average yield of 9 t ha⁻¹, N requirement for 100 kg grains was 1.94 kg (1.91–2.04) under 225 kg ha⁻¹ N level and 2.08 kg (2.01–2.19) under 300 kg ha⁻¹ N level, respectively. With the average yield of 10.5 t ha⁻¹, N requirement for 100 kg grains was 1.95 kg (1.93–2.01)under 225 kg ha⁻¹ N level and 2.09 kg (2.08–2.10) under 300 kg ha⁻¹ N level, respectively. These results suggested that N requirement for 100 kg grains increased with the rising of N application rates. Correlation analysis showed that there existed highly significantly positive conic correlation between yield and N requirement for 100 kg grains, and the correlation coefficients for early-maturing medium japonica and medium-maturing late Japonica were less than those for the other three types. (3)The N use efficiency decreased with the increase of N application rate, and increased with the extension of the growth duration except in the medium-maturing late japonica. N use efficiency was 31.32%, 37.64%, 38.5%, 41.08%, and 38.11% under 225 kg ha⁻¹ N level , and 28.74%, 36.13%, 37.16%, 40.15%, and 39.42% under 300 kg ha⁻¹ N level, for the five types of rice with extended growth duration respectively. (4) The parameters of N application displayed larger differences in early-maturing medium japonica and medium-maturing late japonica rice which were less suitable for local cultivation, compared with the other three types, while these parameters values of the prevailing varieties (headed varieties) were higher and more stable than those of common varieties. These results demonstrated that the changes of the parameters of N application were much larger, it is feasible for the N quantity required for target yield to be calculated accurately by using Stanford equation under the condition of reasonable variety selection and planting location.

Relationship between Crop Productivity and Ecological Factors in Poplar-Crop Intercropping Systems in Haihe Lowland Area

LIU Yue-Hua, CHEN Yuan-Quan, ZHU Min, QU Bo, SHUI Peng, GAO Wang-Sheng

Acta Agron Sin. 2010, 36(08):  1355-1361.  doi:10.3724/SP.J.1006.2010.01355

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Agroforestry system is an approach to improve land use efficiency, it not only allows for the production of trees and crops, but also makes highly use efficiency of natural resources. Because of its advantages of Agroforestry, large scales of poplar-based Agroforestry systems have been developed in north of China since 2002. Hengshui area, in Hebei province, where lots of poplar-based Agroforestry systems exist, is a typical area lacking in water. Our previous study showed that Agroforestry systems consumed a large quantity of water storing in soil and decreased the production of both trees and underlayer crops as trees grew. To analyze the relationships of crop biomass with 0–40 cm soil moisture, and photosynthetically active radiation (PAR) and temperature, we conducted a study from Oct. 2007 to Oct. 2009 on 6–7 year-old poplar-crop intercropping systems with three different patterns of poplar plantations. Compared with sole crop system, PAR and 0–40 cm soil moisture in Agroforestry systems were reduced by 34.43%–76.71% and 18.67%–42.74% respectively. Crop biomass, PAR and soil moisture all showed significant difference among different Agroforestry systems (P<0.05). Ryegrass biomass was highly correlated with PAR, while soybean biomass was highly correlated with both PAR and soil moisture (P<0.05), with all the correlation coefficients 0.7500 (P<0.05) in both 2008 and 2009. The results showed that Agroforestry systems could product more crop biomass by increasing either PAR or soil moisture. And increasing PAR by removing poplar trees (removing alternate trees in rows, or even removing alternate tree rows) or tree branch pruning was an effective measure under the condition of seriously lacking in water in that area.  

Effects of Nitrogen Nutrition on Photosynthetic Functions of Wheat Leaves under Elevated Atmospheric CO₂ Concentration

ZHANG Xu-Cheng, ZHANG Fu-Suo, YU Xian-Feng, CHEN Xin-Ping

Acta Agron Sin. 2010, 36(08):  1362-1370.  doi:10.3724/SP.J.1006.2010.01362

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Nitrogen application rate is a critical factor led to photosynthesis acclimation of C₃ plant under elevated atmospheric CO₂ concentration. However, current knowledge is inadequate for the responses of photosynthetic electron transport and energy distribution of photosynthesis acclimation to nitrogen application rate in C₃ plant, and the influence of photosynthesis function on photosynthetic electron transport and energy distribution. Using Top Open Chambers, the elevated concentration of atmospheric CO₂ was simulated. Wheat (Triticum aestivum L.) was grown under two nitrogen application rates and two atmospheric CO₂ concentrations. The photosynthetic gas exchange parameters, chlorophyll fluorescence parameters, and chlorophyll content of wheat leaves, were measured at jointing and heading stages to study the influence of nitrogen application on photosynthetic function of wheat leaves exposed to elevated atmospheric CO₂ concentration. The results showed that the photosynthetic rate (P_n), stomatal conductance (G_s), and transpiration rate (T_r) decreased in low-N wheat leaves, and the photosynthetic acclimation appeared. However, in high-N wheat leaves the photosynthetic acclimation did not appear, P_n, G_s, and T_r decreased significantly whereas the leaf WUE increased significantly under elevated atmospheric CO₂ concentration. The photochemical rate, photosynthetic electron rate of PSII (J_F), electronic transport rate of photochemistry (J_C), Rubisco carboxylase rate (V_C), and triose phosphate utilization (TPU) declined significantly in low-N wheat leaves; and were not changed in high-N wheat leaves compared to those under ambient atmospheric CO₂ concentration. The J_C/J_F, V_C/J_C, and V₀/V_C had no significant changes between treatments with different nitrogen application rate and atmospheric CO₂ concentrations. This indicated that nitrogen application may increase the photosynthetic energy use, but have no significant influence on photosynthetic energy distribution. The leaf nitrogen and chlorophyll contents increased when nitrogen was applicated under both treatments of CO₂ concentrations, especially, the photosynthetic nitrogen use efficiency (NUE) in high-N wheat leaves increased under elevated atmospheric CO₂ concentration. It suggested that the photosynthetic energy transport rate and assimilatory ability increased by nitrogen application under elevated atmospheric CO₂ concentration. Thus, the photosynthesis acclimation did not appear in high-N wheat leaves. Because there was a significant interaction between nitrogen application rate and atmospheric CO₂ concentration on photosynthetic energy use in wheat leaves, and the photosynthetic NUE in high-N wheat leaves increased under elevated atmospheric CO₂ concentration but decreased under normal ambient atmospheric CO₂ concentration, it concluded that the nitrogen application affects photosynthesis directly in wheat leaves under elevated atmospheric CO₂ concentration.

Boll Development Characteristics for High-Quality Upland Cotton Cultivars

CHEN Yuan, WANG Yong-Hui, XIAO Jian, LUAN Na, ZHANG Xiang, CHEN De-Hua

Acta Agron Sin. 2010, 36(08):  1371-1376.  doi:10.3724/SP.J.1006.2010.01371

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The objective of this study was to investigate the boll development characteristics of high-quality cotton cultivars. Two cultivars of high quality upland cotton, including hybrid Kemian 3 and conventional Kemian 4, with the conventional fiber quality cultivar Sumian 15 as control were planted on the farm of Jiangsu Provincial Key Laboratory of Crops Genetics and Physiology of Yangzhou University from 2004 to 2005. The results showed that the boll development characteristics were different between high-quality upland cotton and the conventional cotton. In comparison to the control, high quality cotton had longer boll length, similar boll diameter, bigger boll volume and higher boll weight. Kemian 3 had faster increase of the boll length within 10 days post anthesis (DPA), Kemian 4 within both 10 days and 20 to 30 DPA, and both of high quality cotton had slower expansion of the boll diameter within 10 DPA, and shorter expansion period of boll diamete , as well as bigger increase of the boll volume within 20 DPA, especially from 10 to 20 DPA. The boll weight increase was higher after 10 DPA for Kemian 3, and before 20 DPA for Kemian 4. The results suggested that boll length is the important index for high quality fiber cotton breeding and developing bigger and high-weight bolls is the key way in the cultivation for high lint yield and good fiber quality.

Yield Stability and Testing-Site Representativeness in National Regional Trials for Oat Varieties Based on GGE-Biplot Analysis

ZHANG Zhi-Fen, FU Xiao-Feng, LIU Jun-Qing, YANG Hai-Shun

Acta Agron Sin. 2010, 36(08):  1377-1385.  doi:10.3724/SP.J.1006.2010.01377

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Atpresent, arithmetic mean method is commonly used to evaluate the yield stability and adaptability of oat (Avena sativa) varieties, and analysis of variance is used to estimate the error in national regional trials. However, it is difficult to evaluate the varieties accurately, because of the discrepancies across tests and years. In this study, GGE-biplot method was used to analyze the date from the national regional trials for oat from 2006 to 2008. Twelve lines of naked oat were tested in ten sites, and six lines of oat were tested in six sites. The results showed that Bayou 8, Bayou 3, and Zhangyan 2 had higher yield and better yield stability than other lines. Keyan-1 and Baoluo possessed special adaptabilities. For naked oat, Zhangbei of Hebei province, was the best representative testing site; Baicheng of Jilin, Wuchuan of Inner Mongolia, Urumchi of Xinjiang, Chongli of Hebei, and Guyuan of Gansu had better discrimination than other sites, where as, Huining of Gansu and Youyu of Shanxi were the worst. For the oat test, Wuchuan of Inner Mongolia had the best representative; Xining of Qinghai had the best discrimination, but Zhangbei of Hebei was the worst. This article provides a simple and effective method for analyzing data, and evaluating the yield stability and adaptability of oat varieties involved in national regional trials oat and favorite test sites.

RESEARCH ACTIVITIES

Relationship between Super-Molecular Structure Changes and Fiber Quality in Fiber Development Process of Colored Cotton Cultivars

ZHANG Mei-Ling, SONG Xian-Liang, SUN Xue-Zhen, CHEN Er-Ying, DIAO Qing-Long, LI Zong-Tai

Acta Agron Sin. 2010, 36(08):  1386-1392.  doi:10.3724/SP.J.1006.2010.01386

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In order to explore the reasons for poor quality of colored cotton fiber, the experiments were conducted with five cotton (Gossypium hirsutum L.) cultivars, including Zongxu 1 (ZX1), Xincai 1 (XC1), Longlümian 2 (G-7), Lü 1-4560(4560), and the contrast of white cotton Lumianyan 28 (LMY28). Dynamic changes of super-molecular structure and fiber quality and the relations between them in fiber development process of colored cotton were studied by X-ray diffraction technique. The results showed that the ultimate fiber length, fiber 3.2 mm gauge tenacity, fiber maturation and fiber micronaire of all cotton cultivars ranked as LMY28>ZX-1 and XC-1>G-7 and 4560. The corresponding crystalline grain size increased constantly and orientation parameters diminished gradually in fiber development process, but there were differences among different cultivars. Compared with the white cotton LMY28, ZX-1 and XC-1 had low initial value, too large amplitude and slightly lower termination value for crystalline grain size of fiber; low initial value, small diurnal variation and high termination value for orientation parameters. For G-7 and 4 560 fibers, the initial value of crystalline grain size was low, the increased amplitude was small and the termination value was slightly lower; the initial value of orientation parameters was high, diurnal variation was small and the termination value was high. The crystalline grain size had a correlation with 3.2 mm gauge tenacity (r=0.89621^*), as well as, the orientational distribution angle-ψ (°) and spiral angle-φ (°) had a negative correlation with fiber 3.2 mm gauge tenacity, fiber maturation and fiber micronaire (r= –0.93816^* ~ –0.90233^*), moreover, the orientational separate angle –α (°) had a negative correlation with fiber length (r= –0.97314^**). In conclusion, the poor quality of colored cotton fiber is probably in relation to poor fiber 3.2 mm gaugetenacity, fiber maturation, fiber micronaire, fiber length, resulting from low initial value and termination value of crystalline grain size and high termination value of orientation parameters in fiber development process.

Leaf Rust Resistance in 27 Diploids and 10 Tetraploids of Wheat Relatives

YUAN Jun-Hai, CHEN Wan-Quan

Acta Agron Sin. 2010, 36(08):  1393-1400.  doi:10.3724/SP.J.1006.2010.01393

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Resistance of 37 accessions of wheat relatives, including 27 accessions of diploid and 10 accessions of tetraploid, to 5 prevalent pathotypes of Puccinia triticina was identified in the field at adult plant stage. Three accessions of Triticum tauschii, one accession of T. dicoccoides, and 3 accessions of T. durum exhibited immunity and one accession of T. monococcm, nine accessions of T. tauschii, and one accession of T. durum were resistant to the pathotypes. This result suggests that the resistance genes involved in these resources are of great value. Based on infection types (ITs), leaf rust resistance gene(s) for the 37 relatives were also postulated with eighteen differential pathotypes under different temperatures at seedling stage. In T. tauschii accessions, Y192 might carry Lr40; Ae37 and Y190 might carry Lr41. Four accessions of durum wheat, i.e. Altar 84, Doliu, Dr147, and Volcani 447, might carry Lr23 and unknown Lr gene(s). There were no putative Lr genes in 10 accessions of T. tauschii, such as Ae39, T96243 and Y193, and T. dicoccoides. At adult plant stage, Ae39, T96243, and Y193 showed ITs from “I” to “R”, with the severity less than 10%. This indicates that those materials probably possess adult plant resistance (APR) against Puccinia triticina.

Effects of Biogas Slurry Combinated with Urea on Photosynthetic Characteristics and Yield of Winter Wheat

FENG Wei, GUAN Tao, WANG Yong-Hua, GUO Tian-Cai, WANG Chen-Yang, ZHU Yun-Ji

Acta Agron Sin. 2010, 36(08):  1401-1408.  doi:10.3724/SP.J.1006.2010.01401

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A two-year field experiment was carried out to study the physiological basis of photosynthesis when biogas slurry was jointly applied with urea in wheat (Triticum aestivum L.) and to suggest the proper method for applying biogas slurry. Under the control of total input of nitrogen, the treatments with basal biogas slurry and topdressed urea showed relative high values of PSII potential activity (F_v/F_o), the maximal quantum efficiency of PSII photochemistry (F_v/F_m), photochemical quenching coefficient (q_P), electron transport rate (ETR), overall photochemical quantum yield of PSII (Φ_PSII), and Pn and low values of non-photochemical quenching coefficient (q_N) of flag leaf from heading to maturity of wheat. The best performance of P_n and chlorophyll fluorescence parameters was observed in the treatment of basal biogas slurry (25%) + topdressed urea (75%), which also showed the highest yield of 8 277.90 kg ha^-1 and 7 318.07 kg ha^-1 in 2007–2008 and 2008–2009. The only application of biogas slurry resulted in poor chlorophyll fluorescence parameters and low P_n because of plant malnutrition, and ultimately a significant lower yield than other treatments. Although the highest F_v/F_o and F_v/F_m were observed in the treatment with urea applied only at heading stage, there were obvious unbalanced chlorophyll fluorescence parameters, such as a continuously low level of q_P, a continuously high level of q_N, and the unstable ETR and Φ_PSII across years. The results suggest that the proper application of biogas slurry in combination with chemical fertilizers may promote grain yield of wheat through optimizing photosynthetic functions, and biogas slurry applied before sowing is better than topdressed at jointing stage.

Development of Soybean Germplasm Lacking of 7S Globulin α-Subunit

LIU Shan-Shan, TENG Wei-Li, ZHANG Bin-Bin, GE Yu-Jun, DIAO Gui-Zhu, ZHENG Tian-Hui, JIANG Zi-Qin, CENG Rui, WU Shuai, LI Wen-Bin

Acta Agron Sin. 2010, 36(08):  1409-1413.  doi:10.3724/SP.J.1006.2010.01409

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α-subunit of soybean β-conglycinin is one of the major allergens in soybean products. It is possible to reduce or remove the allergens from soybean by development of mutant lines. In this study, a cross was made between 10 major varieties in Heilongjiang province of China and “riB” lacking α'-, α-, and 11S acidic subunits in order to breed soybean variety characterized by α-subunit null. F₁ seeds were sown individually and individual plants were harvested to obtain F₂-progeny seeds. Subunit compositions of seeds in F₁ and F₂ were examined for storage protein by SDS-PAGE. The results showed that all the F₁ seeds obtained from cross contained α'- and α-subunits. Five band types of 7S globulin in the F₂-progeny were observed including α-null, (α+A_1aA_1bA₂)-null, A₃-null, (α'+A₄)-null, and (α'+α)-null types.

Cytological and Cytochemical Observation on Microspore Abortion of GMS and CMS in Kenaf (Hibiscus cannabinus L.)

ZHOU Qiong, LI Hua, ZHAO Jia, ZHOU Rui-Yang

Acta Agron Sin. 2010, 36(08):  1414-1424.  doi:10.3724/SP.J.1006.2010.01414

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Kenaf (Hibiscus cannabinus L.) is a potential alternative crop developed for fiber production, but the utilization of hybrids of the sterile line combination in production was seldom reported. Nuclear male sterile lines were discovered from the maintainer line L23B by Dr. Zhou Ruiyang in 2005, and six cytoplasmic male sterile (CMS) lines including cytoplasmic male sterile (CMS) line L23A were identified in 2007. For exploring the mechanism of male sterility, it is necessary to study the changes of some metabolic materials in the developing anther. Microsporogenesis of cytoplasmic male sterile (CMS) line L23A, together with its maintainer line L23B and genic male sterile (GMS) line L23BS which is a mutant of L23B, was studied by microscopic observation with cytological and cytochemical methods. The results indicated that microspore deformation of cytoplasmic male sterile (CMS) lines L23A occurred at different stages. Some anthers contained degenerated pollen mother cells (PMCs) which might result in empty pollen sac; some PMCs failed to pass meiosis; some microspores could not be released from tetrad successfully; andtapetal cells vacuolated. Cytochemical studies indicated there were a little protein and a few starch grains in the young anthers. During the growth of anther, no protein and less starch were observed. In genic male sterile (GMS) line L23BS, some microspores were unable to escape from tetrad and aborted mainly between tetrad and mononuclear pollen stages. Before then protein and starch deposited as normal which disappeared gradually after tetrad stage. It should be noted that the protein and starch disappeared gradually, but the content of big starch grains in L23BS connective did not changed during its microsporogenesis.