结实期氮磷营养水平对水稻根系分泌物的影响及其与稻米品质的关系

以扬稻6号（籼稻）和扬粳9538（粳稻）为材料，在水培条件下自抽穗至成熟期进行0 N（不施N）、1/2 N(标准Espino营养液的1/2 N)、0 P（不施P）、1/2 P(标准Espino营养液的1/2 P)以及对照（全NP，标准Espino营养液的N、P量）5种处理，研究了水稻根系分泌物的变化及其与稻米外观品质、蒸煮食味品质及蛋白质组分的关系。结果表明，与对照相比，结实期氮素胁迫（0 N）明显降低了水稻的根系活力，降低了各种有机酸、氨基酸及离子的分泌量，加速了根系的衰老；磷胁迫（0 P）显著增加了根系有机酸、氨基酸及各种离子的分泌。相关分析表明，结实前中期（花后10 d和20 d）根系分泌的酒石酸、柠檬酸和氨基酸与籽粒垩白度、直链淀粉、崩解值呈显著或极显著负相关，与淀粉谱的消减值呈极显著正相关；根系分泌的苹果酸与籽粒垩白度、直链淀粉、崩解值呈极显著正相关，与淀粉谱的消减值呈极显著负相关；根系分泌的Ca²⁺]、K⁺]、Na⁺]、NO₃^-]、NH₄⁺]、PO₄^3-]与稻米的垩白度、直链淀粉含量、蛋白质组分也显著或极显著相关。表明根系分泌物与稻米品质的形成有密切的关系，N、P营养水平对根系分泌物有调控作用，进而影响稻米品质。

Effects of Nitrogen and Phosphorus on the Root Exudates during Grain Filling and Their Relations with Grain Quality of Rice

Root exudates of plants,such as organic acids and ions,play a role in regulating plant growth and development.The purpose of this study was to investigate how nitrogen(N) and phosphorous(P) nutrients affect the production of root exudates and rice quality.Two rice cultivars,Yangdao 6(indica) and Yangjing 9538(japonica),were used,with five treatments,0 N(without N),1/2 N(1/2 N in the standard Espino nutrition solution),0 P(without P),1/2 P(1/2 P in the standard Espino nutrition solution) and CK(standard Espino nutrition solution),during the grain filling period.The compositions in root exudates and their relations with grain appearance quality,cooking and eating quality,and protein components were analyzed.The result showed that nitrogen stress(0 N) during grain-filling significantly reduced root activity,concentrations of organic acids,amino acids,and ions in the root exudates,accelerated the root senescence.However,phosphorus stress(0 P) significantly increased the concentrations of organic acids,amino acids,and ions.Correlation analysis showed that the concentrations of tartaric acid,citric acid,and amino acid in root exudates were negatively correlated with chalkiness,amylose content,and breakdown values,and significantly and positively correlated with the setback values at early and mid filling stage(10 and 20 d after anthesis).The malic acid exuded from roots was significantly and positively correlated with chalkiness,amylose content,and breakdown values,and significantly and negatively correlated with the setback value.The ,,,,,and in root exudates were significantly correlated with chalkiness,amylose content,protein compositions.The results suggest that N and P nutrients play a role in regulating the production of root exudates,which influence the grain quality further.