不同基因型水稻苗期氮营养特性差异及综合评价

氮肥过量施用,不仅造成氮肥大量流失,还增加了农业生产成本,对生态环境带来了巨大的威胁。筛选氮高效基因型水稻品种是提高氮素利用效率、降低环境污染的有效途径。本文利用营养液培养方法,研究了55个水稻品种(系)在相同供氮水平(40 mg·L~(-1))、不同供氮形态(NH_4~+-N和NO_3~–-N)条件下苗期吸收与积累氮素的差异。并采用隶属函数法将评价指标进行标准化,基于氮效率综合值,运用分层聚类热图分析,进行55个水稻品种氮效率类型的划分,为氮高效水稻品种的筛选提供依据。在NH_4~+-N和NO_3~–-N培养下,不同水稻品种的整株生物量、茎叶生物量、根系生物量、根系氮含量、茎叶氮累积量差异性显著,变异系数分别在0.69~0.80和0.57~0.74之间。通过因子分析发现,在NH_4~+-N和NO_3~–-N培养条件下的主成分情况相同,第1主成分由整株生物量、茎叶生物量、根系生物量、整株氮累积量、茎叶氮累积量、根系氮累积量决定,主要为反映植株的生物量及氮素累积量指标;第2主成分由不同器官的氮含量决定。综合水稻苗期氮素吸收累积变异特征及因子分析,将整株生物量、茎叶生物量、根系生物量、茎叶氮累积量作为水稻苗期氮高效综合评价指标。根据隶属函数法计算出的氮效率综合值和采用欧氏距离平方拟合的分层聚类热图,55个供试水稻品种可分为氮高效型、氮中效型、氮低效型3大类,分别占供试品种总数的10.91%、27.27%、61.82%。在NH_4~+-N和NO_3~–-N供应条件下,初步确定‘广两优3905’、‘甬优9号’、‘中籼2503’、‘Ⅱ优602’、‘两优766’和‘深两优1813’为氮高效型品种。

Evaluation of nitrogen nutrition characteristics of different rice cultivars at seedling stage

Excessive application of nitrogen (N) fertilizers leads to nitrogen loss and increases the cost of agricultural production. Screening rice cultivars with high N efficiency is an effective approach to improving N use efficiency and reducing environmental pollution. In this paper, hydroponic experiments were conducted to examine the differences in N absorption and accumulation of 55 rice cultivars (lines) at seedling stage. The experiments used the same N dose of 40 mg×L-1 in the form of both NH4+-N and NO3–-N and the evaluation indices standardized using subordinate function of interval 0, 1]. The 55 rice cultivars (lines) were classified based on N use efficiency and hierarchical cluster analysis. There were significant differences in aboveground biomass, including whole plant stem, leaf and root, as well as N content in roots, stems and leaves of the rice cultivars (lines) between treated with NH4+-N and NO3–-N (P < 0.05). Also the ranges of coefficients of variation were 0.69-0.80 and 0.57-0.74, respectively, for NH4+-N and NO3–-N treatments. Factor analysis showed that the principal com-ponents of the NH4+-N and NO3–-N treatments were the same. The first principal component was mainly reflected biomass indices and N accumulation, determined using the whole plant, stem, leaf and root biomass, as well as accumulated N in the whole plant, stem and leaf and root. The second principal component was determined using N content. By combining variation characteristics and factor analysis of N uptake and accumulation in rice, the whole plant biomass, stem and leaf biomass, root biomass, stem and leaf N accumulation were used as indices to evaluate high N use efficiency potentials of rice cultivars (lines) at seedling stage. Calculation of the comprehensive values of N use efficiency, based on the membership function method and fitted hierarchical clustering chart of squared Euclidean distance, showed that the 55 rice cultivars (lines) grouped into three categories — high, medium and low N use efficiencies. Rice cultivars (lines) with high, medium and low N use efficiencies with NH4+-N and NO3–-N treatments accounted for 10.91%, 27.27% and 61.82% of the total rice cultivars (lines), respectively. The whole plant biomass, stem and leaf biomass, root biomass, stem and leaf N accumulation could be used as indices to evaluate the N use efficiency potentials of rice cultivars (lines) at seedling stage. ‘Guangliangyou 3905’, ‘Yongyou 9’,‘Zhongxian 2503’, ‘Ⅱyou 602’, ‘Liangyou 766’ and ‘Shenliangyou 1813’ rice cultivars had high N use efficiency under both NH4+-N and NO3–-N treatments.