苦荞耐低磷基因型筛选及评价指标的鉴定

Screening genotypes and identifying indicators of different Fagopyrum tataricum varieties with low phosphorus tolerance

土壤缺磷是限制我国黄土高原作物高产的主要因子之一,苦荞是黄土高原区优势杂粮作物且不同基因型苦荞对低磷胁迫的响应存在显著差异,因而筛选磷高效利用苦荞基因型成为提高苦荞产量、促进当地农业可持续发展的重要途径.以14份不同基因型苦荞为材料,采用砂培试验,对正常供磷(2 mmol·L-1)和低磷胁迫(0.2 mmol·L-1)下苦荞苗期的农艺性状、生理生化指标以及植株磷利用情况进行测定,通过计算苦荞苗期耐低磷特性,筛选出耐低磷苦荞品种及其评价指标,为苦荞磷高效育种及黄土高原瘠薄土壤栽培提供理论依据.结果表明:低磷胁迫下,各基因型苦荞苗期地上部受影响程度大于根系,地上部形态指标、根系平均直径、根系表面积和根系体积降低,而主根长伸长;苦荞根系活力、可溶性蛋白含量均下降,其他生理生化指标升高;植株全磷含量与磷积累量均降低,但磷利用效率升高.主成分分析将22个单项指标转化成4个相互独立的综合指标(累计贡献率达90.1%),聚类分析将14种苦荞划分成3类:耐低磷型、中间型和磷敏感型.为探讨苦荞苗期耐低磷鉴定指标,以耐低磷性综合评价值(D值)为因变量,各单项指标耐低磷系数为自变量,建立最优回归方程,进行耐低磷预测.最终筛选出根表面积、根长、株高、地上部干质量、酸性磷酸酶、磷积累量、过氧化物酶活性7项指标,可用于苦荞苗期耐低磷能力的快速鉴定.

Soil phosphorus（P） deficiency is one of the main factors that diminish the yield of crops on the Loess Plateau.Fagopyrum tataricumis a dominant cereal plant on the Loess Plateau, whose responses to low-P stress are significantly different and dependent on its genotypes. Therefore,screening genotypes with efficient P utilization is an important approach to increase the yield of F.tataricumand promote the sustainable development of local agriculture. With fourteen F. tataricum genotypes, the agronomic traits, physiology and biochemical characters of F. tataricumat seedling stage under normal（2 mmol·L^-1） and low-P treatment（0.2 mmol·L^-1） were studied by usingsand culture. By examining the characters of selected F. tataricumat seedling stage, the varieties of F. tataricumwith low-P tolerance were screened out and their evaluation indices were assessed to provide theoretical basis for the breeding ofF. tataricumwith high P-efficiency and the infertile soil cultivation on the Loess Plateau. The results showed that under low-P stress, the shoots of all geno-types were more affected than roots, with the decline of shoot aboveground index, average root diameter, root surface area and root volume, whereas the length of main root was elongated. Root activity and soluble protein content were decreased. In contrast, other physiological and biochemical indicators were increased. Moreover, plant total phosphorus content and plant phosphorus accumulation reduced, but phosphorus use efficiency increased. The principal component analysis divided the 22 individual indicators into four mutually independent comprehensive indicators（cumulative contribution rate of 90.1%）. Cluster analysis divided 14 kinds of F. tataricuminto three categories：Low phosphorus tolerant, intermediate and phosphorus sensitive. In order to investigate the index of low-P tolerance ofF. tataricumat seedling stage, the optimal regression equation was established with the comprehensive evaluation value of low-P tolerance（Dvalue） as the dependent variable and the low-P tolerance index of each indicator as the independent variables. Seven indicators of root surface area, root length, plant height, above ground dry mass, acid phosphatase, phosphorus accumulation and POD activity were examined, which could be used for the rapid identification of low-P tolerance of F. tataricumat seedling stage.