水磷耦合对藜麦根系生长、生物量积累及产量的影响

【目的】水肥是旱地农业作物高产的主要限制因素,研究水磷耦合对藜麦根系生长、生物量积累以及产量的影响,探明适合藜麦高产的水磷耦合配比,从而为旱地农业藜麦高产提供理论依据。【方法】以藜麦为研究对象,采用盆栽试验,对藜麦整个生长期进行不同灌水(W1、W2、W3分别按照土壤含水量为田间持水量的35%—45%、55%—65%、75%—85%),不同施磷(P0、P1、P2、P3分别为0、0.1、0.2、0.4 g P_2O_5·kg~(-1))耦合处理,测定藜麦根系形态和生理指标、生物量积累以及成熟期产量。【结果】(1)在相同灌水处理下,不同根系参数(根系表面积、根系总长度、最大根长、根系直径、根体积)均在P2(0.2 g P_2O_5·kg~(-1))水平下达到最大;在相同施磷水平下,根系最大根长与根系总长均在W2(土壤含水量为田间持水量的55%—65%)下达到最大,根系表面积在低磷水平(P0、P1)下,均表现为W2P0W3P0,W2P1W3P1,高磷水平(P2、P3)下,均表现为W2P2W3P2,W2P3W3P3,根系直径与根系体积均随着灌水量的增加逐渐增加;在重度干旱胁迫(W1)下,根系活力在P1(0.1 g P_2O_5·kg~(-1))水平下达到最大,其他灌水处理下,根系活力均在P2(0.2 g P_2O_5·kg~(-1))水平下达到最大。在3种灌水处理下,根系POD、SOD活性均在P2(0.2 g P_2O_5·kg~(-1))水平下达到最高,而根系MDA含量、可溶性糖与脯氨酸含量降到最低。(2)适宜的水磷耦合配比(W3P1、W3P2)有利于藜麦各营养器官生物量(茎重、叶重)的积累以及后期产量的形成,而根重、序重在W2P3组合最优。高水处理更有利于植株对茎、叶生物量的分配,低水处理有利于植株对根、序生物量的分配,在重度干旱胁迫(W1)下,高的施磷量(P2与P3)均显著提高了植株对根重与序重的生物量分配。(3)在3种灌水处理下,施磷量均在P2(0.2 g P_2O_5·kg~(-1))水平下有利于植株顶穗的形成。分枝数、穗数、单株粒重与千粒重均表现出低磷促进,高磷抑制的单峰曲线,均在P2(0.2 g P_2O_5·kg~(-1))水平达到峰值;各施磷水平下,单株粒重与千粒重均在正常灌水(W3)达到最大。【结论】适宜的施磷量P2(0.2 g P_2O_5·kg~(-1))可以促进藜麦根系生长,增大根系与土壤的接触面积,提高根系活力,增强根系抗氧化能力,从而提高藜麦的抗旱能力;适宜的水磷耦合配比(W3P2)有利于藜麦各营养器官生物量的积累以及后期产量的形成。

Effects of Water and Phosphorus Coupling on Root Growth,Biomass Allocation and Yield of Quinoa

【Objective】In arid regions, agricultural plantation is mainly restricted by water and fertilizer. To explore a optimal water/phosphorus ratio and provide a theoretical basis for the high yield of quinoa in arid land. In this study, the effects of water and phosphorus coupling on root growth, biomass allocation and high yield of quinoa (Chenopodium quinoa Willd) were studied. 【Method】 Guinoa was taken as an experimental material and pot-culturing experiment were carried out at 3 levels of water irrigation (W1, W2 and W3 represented 35%-45%, 55%-65% and 75%-85% soil moisture content) and 4 levels of phosphorus fertilizer (P₂O₅ application rates of P0, P1, P2, P3 were 0, 0.1, 0.2 and 0.4 g·kg^-1), and root morphological and physiological indexes, biomass allocation and yield under the conditions of 12 different water and phosphorus coupling treatments were compared. 【Result】 At the same water irrigation level, the root parameters (root area, total root length, maximum root length, root diameter and root volume) were the highest under P2 treatment. At the same phosphorus level, the maximum root length and total root length reached the maximum under W2 treatment, and root area showed W2P0＞W3P0 and W2P1＞W3P1 under low phosphorus treatment (P0, P1). Under high phosphorus treatment (P2, P3) root area showed W2P2＜W3P2 andW2P3＜W3P3. Root diameter and root volume increased with the increasing of water content. Under the severe drought stress (W1) with P1 treatment, root activity were highest; but it was the highest under other water irrigation levels with P2 treatment. POD and SOD activities were highest and MDA was lowest under P2 (0.2 g P₂O₅·kg^-1) treatment across all irrigations; The appropriate phosphorus fertilizer (P2) significantly reduced the soluble sugar and proline content. The appropriate ratio of water and phosphorus (W3P2, W3P1) was beneficial for biomass of stem and leaf weight, and yield of quinoa, while the weight of root and panicle were the highest under W2P3 treatment. High water irrigation benefited for biomass allocation between stems and leaves; Low water irrigation was beneficial forbiomass allocation between root and panicle at 3 water levels, P2(0.2 g P₂O₅·kg^-1) treatment was suitable for formation of apical spike; Low phosphorus promoted the number of branch and spike, 1000-grain weight and grain weight, while they were specific under high phosphorus conditions, and at various levels of phosphorus with W3 treatment gain weight reached the maximum, respectively. 【Conclusion】 The suitable phosphorus supplement (P2, 0.2 g P₂O₅·kg^-1) improved root activity, root growth, increased area of the root contacting and soil, strengthened antioxidant ability of root, and therefore enhanced the drought resistance of quinoa. and the optimal ratio of water and phosphorus (W3P2) was suitable for biomass accumulation and high yield of quinoa.