水稻淀粉合成代谢相关基因与千粒重QTLs的连锁分析

稻米淀粉的合成和积累是水稻千粒重形成的重要基础之一。在水稻千粒重QTLs定位分析基础上，对本研究克隆的14个水稻胚乳淀粉合成与积累相关基因及已报道的和预测的42个相关基因进行了电子定位分析，比较水稻淀粉合成代谢相关基因与千粒重QTLs的连锁关系。发现有38个基因位点与千粒重QTLs连锁，说明千粒重形成与胚乳淀粉积累与淀粉结构形成代谢密切相关。本研究结果将为进一步研究水稻产量形成的分子机理提供参考。     

施肥和化控对高产棉田叶源活性和棉铃发育的调节

对高产条件下棉株各部位棉铃对位叶生理活性的研究表明 ,氮钾肥和 DPC化控的协调运用有效地增加了棉铃对位叶游离氨基酸、可溶性蛋白的含量 ,缩小了中上部、内外围棉铃对位叶 1 ,5 -二磷酸核酮糖羧化酶 ( Ru BPase)的含量间的差距 ,促进了棉铃对位叶光合速率的提高 ,增强了棉株叶源特别是“弱势部位”(棉株外围和上部 )叶源的生理活性 ,达到了促进棉株弱势部位铃重提高的目的 ,从而提高了整株铃重     

10个紫花苜蓿品种耐盐性的比较研究

对10个紫花苜蓿品种种子分别用0%、0.3%、0.7%和1.0%的NaC l溶液进行处理,通过种子发芽率、相对发芽势、幼苗重和幼苗高对各品种种子萌发期耐盐性进行了研究。结果表明:用0.7%或1.0%NaC l溶液性鉴定较为合理;0.7%NaC l溶液处理苜蓿种子,其幼苗重和幼苗高可作为苜蓿品种耐盐的鉴定指标。0.7%、1.0%NaC l溶液处理下,通过测定第3天和第5天各品种种子的发芽势,可以鉴定耐盐性大小。对10个苜蓿品种耐盐性综合研究结果是:龙牧801和巨人201的耐盐性最强,其次是肇东、龙牧803和CW 200;新疆大叶和爱菲尼特的耐盐性最弱。     

源库改变对小麦籽粒蛋白质,淀粉含量及产量的影响

利用蛋白质含量及产量各不相同3个春小麦品种．研究了源库改变对淀粉、蛋白质沉术；及单侏产量的影响．结果表明：源库改变明显地影响着籽粒蛋白质的含量，而对淀粉、可溶性糖含量影响不大；品种间蛋白质含量对源库变化的反应不同；千粒重的增减也因品种而异；淀粉的沉积主要受库的限制，而源库都影响着蛋白含量；旗叶在产量和蛋白形成中起着同样重要作用。     

Genetic variation in bitter pit and fruit calcium concentrations within a diverse apple germplasm collection

Summary Genetic variability in the apple [Malus] fruit disorder bitter pit and fruit calcium concentrations ([Ca]) was determined in 25 seedling families at each of two sites from 1999 to 2000 and again for one site, in 2001. Most trees were free of pit or had low pit incidence, which could be approximated by an over-dispersed binomial distribution. A genetic component to external and internal pit incidence was found across both sites and all years. This effect was irrespective of the use of several cropping factors, average fruit weight or fruit mineral concentrations as covariates in the analyses. Year and/or site always had substantial effects on pit incidence. Interactions of genetic effects with site or year were also detected with large differences in mean pit incidence between sites or years for some families but not others. No relationship was found between mean family pit incidence and mean family [Ca] or mean family harvest date. However fruit [Ca] and harvest date were usually important predictors of within-family variation in pit incidence. For any one seedling, family had the largest effect on bitter pit incidence followed by site and [Ca] and the smallest effect was that of harvest date. [Ca] showed a strong genetic component and estimated family means of [Ca] were consistent at different sites and years. These results suggest that susceptibility of apple genotypes to bitter pit in breeding programmes may be best assessed through screening across multiple sites and seasons. Fruit [Ca] might be useful as an indirect selection index for bitter pit within, but not among families.     

Strong heritability across years and sites for pod wall proportion and specific weight in Lupinus albus and genotypic correlation with other pod and seed attributes

Thinner pod walls might contribute to increased yield potential and adaptation of lupins. Fourteen autumn‐sown genotypes of Lupinus albus L. were evaluated over 2 years at four sites in southern Chile. Pod wall proportion (PWP), pod wall specific weight (WSW) and five other pod‐related characters were measured to estimate their genetic variation, heritability across years and sites, and genotypic and phenotypic correlations among the characters. Ranges for PWP and pod WSW were 22.9−43.1% and 16.4−37.4 mg/cm², respectively. PWP in cultivated L. albus was similar to that reported in L. angustifolius; however, specific weight was substantially lower. Highly significant genotypic effects were found for both characters. Broad sense heritabilities were high for PWP (0.63) and moderate for pod WSW (0.46). These characters were significantly correlated, more so genotypically (r_g = 0.67) than phenotypically (r_ph = 0.36). Selection for low PWP should lead to lower pod wall thickness or density, both of which contribute to pod WSW. Nevertheless, selection for pod WSW could achieve further reductions, particularly if practised among low PWP materials.     

Genetic Variation for Seed Yield in Perennial Ryegrass (Lolium perenne L.)

In perennial ryegrass seed yield is low and unreliable and little is known about the seed-yielding capacity of different cultivars. Therefore, genetic variation for seed yield was studied for therefore, genetic variation for seed yield was studied for three years at two locations. Twelve trials consisting of drilled plots of nine diploid, late-flowering cultivars in four replications were harvested for seed. Significant gentic differences for seed yield and seed weight weight were detected. The ranking of the cultivars for seed yield differed from that for seed weight. The levels of seed yield and seed weight were affected by such environmental factors as year, soil type and crop production year, but interactions of these factors with cultivars were generally not significant. Variation in seed yield was more related to variation in seed number than to variation in seed weight. There were no significant cultivar differences for yield stability. The highest yielding cultivar was superior over a wide range of environments and the seed yield of the poorest cultivar was on average only 64% of that of the best cultivar.     

Selection for resistance to Septoria nodorum in wheat

Summary A population of 572 F₂ derived F₃ lines from six crosses were used to estimate parameters relevant to selection for resistance to Septoria nodorum of wheat. Lines were grown in disease free (fungicide sprayed) and inoculated microplots in 2 replications of a split-plot design in a single environment in 1977. Average yield reduction due to disease was approximately 50%; this was associated with an average septoria score of 50% on the flag leaf, an average septoria score of 42% on the head, and a reduction of 37% in seed weight. Low S. nodorum scores were correlated with late heading date, tall plant height, high grain yield, and high seed weight in diseased plots, and high seed weight % (seed weight in diseased plots expressed as a percentage of seed weight in fungicide sprayed plots).Restricted selection indexes were used to study the relative contributions of disease escape, true resistance, and tolerance to variability in grain yield in diseased plots, seed weight in diseased plots, and seed weight %. True resistance appeared to be the most important factor causing variation in grain yield in diseased plots and seed weight %. Tolerance and escape seemed to be more important for seed weight in diseased plots.Heritabilities of S. nodorum scores on the flag leaf and head were 63% and 52%, respectively. Leaf and head scores could be used most effectively as selection criteria to upgrade resistance in a population before harvest.Selection for high seed weight % slightly reduced yields in disease free plots, although yield in diseased plots and seed weight in diseased plots were increased. However, selection for increased yield or increased seed weight in diseased plots improved yield in disease free plots. It is suggested that direct selection for yield or seed weight in diseased plots is likely to achieve more desirable goals than selection for seed weight %.     

NCT对小麦衰老生理的影响

以新合成的NCT配制成不同浓度的水溶液，对灌浆初期的大田小麦进行叶面喷施，以喷清水作对照，并以与NCT相同浓度梯度的NAA水溶液作对比处理，测定了喷后不同时期小麦旗叶的相对电导率、叶绿素含量、超氧化物歧化酶（SOD）活力及丙二醛（MDA）含量。结果表明：NCT能延缓灌浆期SOD活力，使叶绿素含量降低，控制相对电导率和MDA含量的升高，并使小麦穗粒重和千粒重增加，其效果明显优于NAA。     

Genetic improvement in wheat yield and associated traits. A re-examination of previous results and the latest trends

Two field experiments were carried out with seven wheat cultivars (three of them, including a commercial hybrid, released during the last 10 years) representing different eras of plant breeding, to evaluate genetic improvement over the last century in grain yield, height, biomass, harvest index and grain yield components. Plots were fertilized and irrigated, and lodging and diseases were prevented. Main culm height was negatively correlated with the year of release of the cultivars, probably as a consequence of selection for increased lodging resistance. There was no significant association between total above-ground biomass and year of release of the cultivars. On the other hand, grain yield increased as newer cultivars were released. Results indicate that during recent years harvest index has been kept as the main attribute responsible for increases in grain yield. In general, number of grains/m² was associated with increases in grain yield during the century. However, the newest cultivars showed an increased grain weight. In both growing seasons, cultivars released before 1980 showed a trend towards reduced grain weight, but cultivars released after 1987 had a similar number of grains per m² with a higher grain weight than their predecessors. This was probably because the most modern cultivars have a longer grain-filling duration with a similar length of growth cycle.