[Objective] The aim was to evaluate the effects of different concentrations of ABA on photosynthetic characteristics of pods and yield of Brassica napus and analyze the relationships between ABA concentration and yield components, to provide theoretical basis for cultivation of high-yield rapeseed. [Method] At the end of flowering stage, the rape plants were separately sprayed with 1, 2, 100 and 200μmol/L of ABA; photosynthetic parameters, water use efficiency （WUE）, yield and yield components of the rape plants were investigated 0, 5, 10 and 15 d later, respectively. [Result] ABA treatment with different concentrations significantly changed pod photosynthetic parameters and yield components of rapeseed. Low concentra- tions of ABA could improve pod＇s net photosynthetic rate and yield components while high concentrations had the contrary effect. [Conclusion] Whether ABA func- tioned in inhibiting or promoting role might depend on the interaction between endogenous hormone levels and exogenous ABA concentration. Improvement of WUE would be the main reason for yield increasing.
[Objective] The paper was to explore the impact of 5-aminolevunic acid（ALA）treatment on growth of winter oilseed rape（Brassica napus L.）seedlings and its mechanism.[Method] The effects of ALA on abscisic acid（ABA）contents in plant organs and xylem saps were investigated through hydroponic experiment.Four treatments including seed soaking with 0,25,50 and 75 mg/L ALA solutions（CK,A1,A2 and A3）for 6 h were set in the test.[Result] In addition to A3 treatment which made the dry weights of oilseed rape seedlings slightly decrease,after seed soaking with ALA,dry weights,net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）of plants significantly increased compared with control.ABA concentrations in plant shoots and xylem saps increased in different levels after seed soaking with ALA.[Conclusion] The increasing endogenous ABA contents might be an explanation for promotion effect of ALA application on the growth of winter oilseed rape seedling.
[Objective] The aim of this paper is to investigate the influences of exogenous 5-aminolevulinic acid （5-aLA） application on the growth and mechanism of winter oilseed rape （Brassica napus L.） before winter. [Method] For this purpose a split-plot experimental design with four treatments of seed soaking with 0,25,50 and 75 mg/L ALA solution （CK,A1,A2 and A3） was carried out from October 2009 to January 2010 in order to observe the influences upon the growth and relevant physiological indexes of Zhongshuang 9. [Result] Seed soaking with ALA solution significantly promotes the growth of double-9 before winter,which is probably due to the fact that ALA application enhances its photosynthesis,absorption of nutrients,and its anti-oxidation abilities. The research also finds that ALA treatment notably increases its photosynthetic pigment contents,root activities,leaf nitrate reductase activities,soluble sugar contents,antioxidase activities,and significantly decreases malondialdehyde（MDA） content. [Conclusion] These results indicate that seed soaking with 50 mg/L ALA solution might have a potential application in increasing the productivity of winter oilseed rape in agricultural management.
