结实期钾、钙对水稻根系分泌物与稻米品质的影响

摘要

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设OK(不施K)、1/2K(标准Espino 营养液的1/2K)、0Ca(不施Ca)、1/2Ca(标准Espino营养液的1/2Ca)以及对照(全K、Ca,标准Espino营养液的K、Ca量)5种处理,研究了水稻根系及根系分泌物的变化及其与稻米外观品质、蒸煮食味品质的关系.结果表明,与对照相比,结实期无钾处理(0K)明显降低水稻根系活力、根系ATP酶活性和根系柠檬酸及Ca2+、K+和NH4+的分泌量,加速根系的衰老;无钙处理(0Ca)显著降低根系草酸及Ca2+、K+和NH4+的分泌.相关分析表明,根系分泌的草酸与稻米的垩白米率、垩白度和胶稠度均呈极显著正相关;根系分泌的柠檬酸与垩白米率、垩白度、崩解值呈极显著负相关,而与消减值呈极显著正相关;结实前中期(花后10 d,20 d)根系分泌的[K+]、[Ca2+]与稻米垩白米率、垩门度和直链淀粉含量均呈显著或极显著负相关;根系分泌的[NH4+]与直链淀粉含量也呈极显著负相关.表明根系分泌物与稻米品质有密切的关系,K、Ca营养水平对根系分泌物有调控作用,进而影响稻米品质.%Potassium (K) and calcium (Ca) play important roles in regulating plant growth and development.The purpose of this study was to investigate how K and Ca nutrients affect the changes in the root exudates and their relations with appearance quality, eating and cooking quality using two rice cultivars, Yangdao 6 (indica) and Yangjing 9538 (japonica).Five treatments, 0K (without K), 1/2K (1/2K of the standard Espino nutrition solution), 0Ca (without Ca), 1/2Ca (1/2Ca of the standard Espino nutrition solution), and CK (standard Espino nutrition solution) were conducted from the heading stage to maturity.The results showed that 0K significantly decreased root activity, ATPase activity and the concentrations of citric acid, and Ca2+, K+, and NH4+ in the root exudates, accelerated root senescence.The treatment of 0Ca significantly decreased the concentrations of oxalic acid, Ca2+,K+ and NH4+ in the root exudates.The concentration of oxalic acid was very significantly and positively correlated with chalky kernel percentage, chalkiness and gel consistency in rice.And the concentration of citric acid was very significantly and negatively correlated with chalky kernel percentage, chalkiness and the value of breakdown, whereas very significantly and positively correlated with the value of setback.The concentrations of K+ and Ca2+ in root exudates during early or middle grain filling period (10 d or 20 d after heading stage) were significantly or very significantly and negatively correlated with chalky kernel percentage,chalkiness and amylose content.The concentration of NH4+ in the root exudates was also very significantly and negatively correlated with amylose content in rice grains.These results indicate that root exudates are closely associated with grain quality, and K and Ca could regulate root exudates, and consequently, affect grain quality in rice.