低钾胁迫对棉花光合作用和光合产物分配的影响

Effects of low potassium stress on the photosynthesis and photosynthate partitioning of cotton

分别选用钾高效和钾低效棉花基因型各一个进行大田试验,探讨低钾胁迫对棉花光合作用和光合产物的积累分配的影响。结果表明:低钾胁迫降低了棉花叶片的净光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)和气孔导度(Gs),降低了棉花的生物量,低钾胁迫同时促使光合产物较多地分配到营养器官,降低了生殖器官分配的比例,收获指数降低。不同棉花基因型的光合特性存在着差异,钾高效基因型(HG)的Pn、Tr、Ci和Gs无论施钾与否均高于钾低效基因型(LG)。不同棉花基因型光合产物的分配模式存在着差异,无论施钾与否,HG的营养器官积累的干物质相对较少,往生殖器官分配的较多,收获指数高,而LG相反。2个基因型在苗期和蕾期的生物量没有显著性差异,而在桃期和吐絮期,HG的生物量显著高于LG。HG的钾利用指数在桃期和吐絮期均显著高于LG。研究表明,增施钾肥能够改善棉花叶片的光合功能并提高光合产物的分配效率。

Taking two cotton cultivars of high efficient gen^type （HG） and low efficient genotype （LG） as test objects, a field experiment was conducted to study their photosynthesis and photo- synthate accumulation and partitioning under low potassium （K） stress. Low K stress decreased the leaf net photosynthetic rate （Pn）, transpiration rate （Tr）, stomatal conductance （G~）, intercellular CO2 concentration （ C~ ）, and plant biomass, promoted the partitioning of photosyn- thates to vegetative organs but decreased the partitioning ratio to reproductive organs, and thus, decreased the harvest index. There existed differences in the photosynthetic parameters between the two cotton cultivars. Whether K was applied or not, HG cuhivar had higher P,1, Tr, Gs, and C~, as compared with LG cuhivar. There also existed differences in the biomass partitioning between the two cotton cuttivars. The HG cultivar partitioned less biomass to vegetative organs but more to reproductive organs, and maintained a higher harvest index, while LG cultivar was in adverse, regardless of the K condition. The biomass of the two cotton cultivars had no significant difference at seedling stage and squaring stage, but the biomass of HG cuhivar was higher than that of LG cultivar at boiling stage and boll opening stage. Moreover, the K use index of HG cul- tivar was higher than that of LG cuhivar at bolling stage and boll opening stage. This study indi- cated that K application could improve the photosynthetic function of cotton leaf and the partitio- ning efficiency of photosynthates.