Development of a technique to study seedling emergence in response to moisture deficit in the field —The seed bed environment*

The ability of crops of sorghum (Sorghum bicolor (L.) Moench) to establish in farmers' fields depends largely on its capacity to germinate and emerge under limited soil moisture conditions. Studies on germination under moisture stress have been previously conducted using osmotic media which do not wholly reproduce the conditions of the seed bed in the field. Hence the need for a field screening technique. A line source irrigation system was used to provide five moisture regimes ranging from -0.08 MPa to -0.92 MPa. The drying rate of the soil and the soil temperature depended largely on incident radiation, and the relationship between the moisture content and daily soil temperature and daily radiation was consistant. Total porosity of the seed bed, derived from bulk density measurements and particle density ranged from 43.8% to 45.3%, which would allow sufficient aeration when as in the experiments conducted here, water content was low (> 0.14 g/g). Under these seed bed conditions the pattern of response of emergence to the moisture gradient was linear or curvilinear. Genotypic differences existed for emergence and its response to water level. The field method developed is useful for identifying genotypes able to germinate and emerge under conditions of low seed bed moisture.     

植物根构型特性与磷吸收效率

植物根构型,即根系在生长介质中的空间造型和分布,与磷吸收效率密切相关;认识植物根构型,可为植物磷效率的遗传改良提供依据。长期以来,人们试图定量描述植物根构型,确立一个能客观全面地描述根系三维立体构型的综合指标。试验指出,植物主要通过向地性变化和根冠之间的碳源分配来改变根构型,从而影响磷吸收效率;根系向地性变化可由缺磷等因素所诱导,且存在着一定的遗传变异性。有证据表明,根构型对低磷胁迫的适应性变化是     

棉花纤维品质分子改良研究进展

棉花纤维是重要的天然纤维和纺织工业原料。目前国内外棉花育种家除了利用常规技术外,还大规模开展了棉花纤维品质分子改良的育种研究。综述了利用基因工程手段进行棉花纤维品质改良的分子育种相关研究进展。