磷素对紫花苜蓿分枝生长及生理的影响

Effects of Phosphorus on the Branch Growth and Physiology of Medicago sativa

为探讨磷素对短期栽培紫花苜蓿分枝生长及相关生理的影响,以非秋眠性品种WL525HQ为试验材料,田间试验和盆栽试验测定了不同磷素水平下紫花苜蓿的分枝特性指标、光合指标和根系养分情况。结果表明:磷素处理对紫花苜蓿的根颈分枝数和茎分枝数影响不显著,但显著增加了根颈分枝单枝重和茎分枝单枝重(P<0.05),从而提高了单株干重;磷素处理提高了紫花苜蓿的光合性能,与对照相比,P_(2)O_(5)10、15和20 g盆栽处理第1茬的净光合速率显著提升了14.0%、16.7%和14.2%;磷素处理有提高紫花苜蓿根系中可溶性糖、淀粉和总的非结构性碳水化合物(TNC)含量的趋势,且显著提高了其贮存量(P<0.05);总氮含量和贮存量随着磷素用量的增加而显著增加(P<0.05);紫花苜蓿各茬刈割后的干物质日增量随着磷素用量的增加而显著升高(P<0.05),且其再生速度与根系养分的贮存量呈显著正相关关系(P<0.05)。综合试验结果:磷素处理主要通过增加紫花苜蓿分枝的单枝重来提高干物质产量,且磷素增加分枝单枝重的原因在于磷素促进了根系与新生枝间的养分流动,从而加快了新生枝的生长。

In order to investigate the effects of phosphorus on the branching growth and the related physiology of Medicago sativa under the short-term cultivation,the non-fall dormancy variety WL525 HQ was used as the experimental material.The branching characteristics,photosynthetic indexes and root nutrients of Medicago sativa under different phosphorus levels were determined by field experiment and pot experiment.The results showed that phosphorus treatment had no significant effect on the number of root crown shoots and shoot branching of Medicago sativa,but significantly increased the single branch weight of root crown shoots and shoot branching(P<0.05),thus increasing the dry weight per plant.The phosphorus treatment improved the photosynthetic performance of Medicago sativa.Compared with the control group,the net photosynthetic rate of the first crop treated with 10 g,15 g and 20 g P_(2)O_(5)under the potted cultivation was significantly increased by 14.0%,16.7%and 14.2%,respectively.The phosphorus treatment tended to increase the contents of soluble sugar,starch and total non-structural carbohydrate(TNC)in the roots of Medicago sativa,and significantly increased their storage capacity(P<0.05).The total nitrogen content and its storage capacity increased significantly with the increase of phosphorus application(P<0.05).The daily increment of dry matter of Medicago sativa after mowing was significantly increased with the increase of phosphorus application rate(P<0.05),and the regeneration rate was significantly positively correlated with the storage capacity of root nutrients(P<0.05).The comprehensive test results showed that:the phosphorus treatment has improved the dry matter yield of Medicago sativa mainly by increasing the single branch weight of branches,and the reason why phosphorus could increase the single branch weight of branches was that the phosphorus has promoted the flow of nutrients between roots and newborn branches,thus accelerating the growth of newborn branches.