不同抗旱性冬小麦根系时空分布与产量的关系

Relationship between spatiotemporal distribution of roots and grain yield of winter wheat varieties with differing drought tolerance

为明确不同抗旱性冬小麦品种(Triticum aestivum L.)根系时空分布及其与产量的关系,以抗旱性品种长武134、长旱58和干旱敏感性品种小偃22、西农979为材料,采用根箱试验研究干旱胁迫和充分供水条件下4个品种在拔节期、开花期和成熟期根系总生物量、总根长密度、根系在表层(0—20 cm)和深层(20 cm以下)土壤中的垂直分布、动态变化及其对产量的影响。结果表明,干旱胁迫下抗旱性品种产量显著高于干旱敏感性品种,其中长旱58产量最高,西农979最低;充分供水条件下,西农979产量最高,长武134最低,长旱58与小偃22之间没有差异。相关分析表明,产量与各生育时期根系性状均有显著关系。多元逐步回归分析的结果显示,干旱胁迫和充分供水条件下,拔节期深层根生物量对产量有正效应,而成熟期总根长密度对产量表现为负效应。通径分析表明,干旱胁迫下,根系性状对产量的直接贡献大小为开花期总根长密度(|0.54|)>拔节期深层根生物量(|0.36|)>成熟期总根长密度(|-0.31|);充分供水时,成熟期总根长密度(|-1.56|)>拔节期深层根生物量(|0.83|)。研究表明,减少成熟期总根长密度,增加拔节期深层根生物量对抗旱性及干旱敏感性冬小麦品种产量均有显著的正效应,增加开花期根长密度有利于提高抗旱性冬小麦产量。

The spatiotemporal distribution of roots affects a plant′s ability to uptake soil resources,which ultimately influences grain yield.A rhizobox experiment was conducted with or without water stress using four winter wheat(Triticum aestivum L.)cultivars with differing drought tolerance(drought tolerant:Changwu 134 and Changhan 58;drought sensitive Xiaoyan 22 and Xinong 979).Plants were grown in soil-filled rhizoboxes under moderate drought(MD,55%of field capacity)and well-watered(WW,85%of field capacity)conditions.When exposed to drought stress,the yield of the drought tolerant cultivars were greater than that of the drought sensitive cultivars.Changhan 58 had the highest grain yield and Xinong 979 had the lowest.When well-watered,the highest grain yield was from Xinong 979,while the lowest was from Changwu 134,and the yields from Changhan 58 and Xiaoyan 22 were similar.A correlation analysis showed that root traits at different growth stages was significantly correlated with grain yield.A multiple stepwise regression analysis showed that the subsoil root biomass at stem elongation had a significant positive effect on grain yield,while total RLD(root length density)had a negative effect on grain yield regardless of water supply.A path analysis showed that the order of direct contribution to grain yield was that of total RLD at anthesis(|0.54|)>subsoil root biomass at stem elongation(|0.36|)>total RLD at maturity(|-0.31|)when under moderate drought.When under well-watered condition,the higher direct contribution to grain yield was that of total RLD at maturity(|-1.56|)and then subsoil root biomass at stem elongation(|0.83|).We conclude that reducing total RLD at maturity and increasing subsoil root biomass at stem elongation contributed to the high yield.The cultivars with increased total RLD at anthesis may increase grain yield in rain-fed dryland agricultural regions.