在间作系统中，高位作物往往会对低位作物造成遮荫胁迫，从而影响低位作物的农艺特性。本研究探讨了遮荫胁迫下不同花生品种间光合、生理及产量变化的差异机制。在花生的生殖生长时期对4个花生品种S60、C4、P12和YS151进行77天的遮荫胁迫。结果表明，遮荫胁迫下，S60和P12的产量和干物重降低幅度均低于C4和YS151。遮荫胁迫下S60和P12的抗氧化酶活性高于C4和YS151。遮荫胁迫下，S60和P12的捕光能力高于C4和YS151，这与叶绿素a、b含量和叶绿素a/b比值的变化有关。遮荫胁迫下，C4和YS151的净光合速率、气孔导度和蒸腾速率降低，而胞间CO2浓度升高。非气孔限制因子降低了遮荫胁迫下花生的光合能力。遮光胁迫下，S60和P12的PSII (Fv/Fm)和非光化学猝灭(NPQ)的最大光化学效率均高于C4和YS151。以上结果表明，S60和P12在弱光环境中可以吸收更多的光能进行光合作用，并将多余的能量以热量的形式耗散，以提高其防光能力。本研究解释了造成遮荫胁迫下花生品种间抗逆性差异的机制，为耐荫品种的选择提供了生理参数。

Starch is the most important component in endosperm of sorghum grain.  Usually, two types of starch are present: amylose (AM) and amylopectin (AP).  The levels of AM and AP contents play a significant role in the appearance, structure, and quality of sorghum grains and in marketing applications.  In the present study, a panel of 634 sorghum (Sorghum bicolor (L.) Moench) accessions were evaluated for starch, AM, and AP contents of grain, which included a mini core collection of 242 accessions from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India, and 252 landraces and 140 cultivars from China.  The average starch content was 67.64% and the average AM and AP contents were 20.19 and 79.81%, respectively.  We developed a total of 260 000 high-confidence single nucleotide polymorphism (SNP) markers in the panel of 634 accessions of S. bicolor using specific locus amplified fragment sequencing (SLAF-seq).  We performed genome-wide association studies (GWAS) of starch, AM, and AM/AP of grain and SNP markers based on a mixed linear model (MLM).  In total, 70 significant association signals were detected for starch, AM, and AM/AP ratio of grain with P<4.452×10^–7, of which 10 SNPs were identified with significant starch, 51 SNPs were associated with AM, and nine SNPs were associated with the AM/AP ratio.  The Gene Ontology (GO) analysis identified 12 candidate genes at five QTLs associated with starch metabolism within the 200-kb intervals, located on chromosomes 1, 5, 6, and 9.  Of these genes, Sobic.006G036500.1 encodes peptidyl-prolyl cis-trans-isomerase CYP38 responsible for hexose monophosphate shunt (HMS) and Sobic.009G071800 encodes 6-phospho-fructokinase (PFK), which is involved in the embden-meyerhof pathway (EMP).  Kompetitive allele specific PCR (KASP) markers were developed to validate the GWAS results.  The C allele is correlated with a high starch content, while the T allele is linked with a low level of starch content, and provides reliable haplotypes for MAS in sorghum quality improvement.

Starch content is a key factor affecting sorghum grain quality. The research of sorghum grain starch accumulation and the related synthesis enzyme activities has great significance for understanding the mechanisms of starch metabolisms. The differences between a high and a low starch content sorghum hybrids (Tieza 17 and Liaoza 11, respectively) in grain starch accumulation and the related synthesis enzyme activities were assessed following imposition of water stress during flowering stage. The total starch, amylase and amylopectin accumulation all decreased at the mid-late stage of grain filling under drought stress during flowering stage. The maximum and mean accumulation rates also decreased. During grain filling, soluble starch synthase (SSS), granule-bound starch synthase (GBSS), starch branching enzyme (SBE), and starch debranching enzymes (DBE) activities were all affected, though differently. Drought stress reduced starch accumulation in a larger extent for Tieza 17 than Liaoza 11. Drought stress during flowing stage reduced starch synthesis enzyme activities, thus reducing starch accumulation in grains, and the differences between starch components were also demonstrated under drought stress.