Field trial was conducted to investigate the photosynthetic rate and biomass of leaves at different positions during seed development of Cleistogenes songorica,a widely spread native grass species that has potential to be used as forage crop and trufgrass in arid and semi-arid regions of northwest China.Meanwhile,correlation analysis was carried out between seed yield and photosynthetic performance and biomass of leaves at different positions during seed development.The results showed that photosynthetic rate,biomass and water content of leaves at the same position significantly decreased during seed development,in the same seed development stage,there were also significantly different in photosynthetic rate,biomass and water content of leaves at different positions.Photosynthetic contribution of leaves at positions 1～4 showed a significantly increase during seed development,while significantly decreases were observed at positions 5～7.With the decline of leaf position,photosynthetic contribution increased first,and then descended significantly,regardless of the seed development stage.Total leaf biomass was significantly decreased with the development of seed,while spikelet biomass showed an adverse trend.There was a positive correlation between seed yield and photosynthetic rate and biomass of leaves at positions 1～5 before milk stage,while photosynthetic rate and biomass of leaves at position 6 positively correlated with seed yield only at peak flowering stage,furthermore,these data of leaves at position 7 showed negative correlation with seed yield during the entire seed development period.Total leaf biomass positively correlated with seed yield at peak flowering stage and seed filling stage,while negatively at other stages,on the contrary,negative correlation was observed between spikelet biomass and seed yield at peak flowering stage,yet positive correlation were obtained at subsequent stages.In conclusion,leaves at positions 1～5 were pivotal for C.songorica seed production,especially from peak flowering stage to milk stage.%在田间条件下研究了无芒隐子草(Cleistogenes songorica)种子发育各时期不同位叶的净光合速率及重量等指标,并分析了种子产量与其的相关性.结果表明:相同位叶在种子发育过程中净光合速率与叶重量、含水量均呈下降趋势,在同一时期,各位叶净光合速率、叶重量与含水量差异显著.第1～4叶光合贡献率随种子发育呈上升趋势,第5～7叶随种子发育逐渐下降,同时期各位叶光合贡献率与叶重量比例随叶位降低先增加后减小.叶总重量随种子发育逐渐减小,穗重量则显著增加.前5枚叶片的净光合速率与重量在乳熟期以前始终与种子产量呈正相关,而第6位叶仅在盛花期与种子产量呈正相关,第7位叶在种子发育过程中始终与种子产量呈负相关.叶总重量在灌浆期前与种子产量呈极显著正相关,此后则呈负相关;穗重量在盛花期与种子产量呈负相关,此后则始终为正相关.
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