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施肥深度对不同水分条件下冬小麦根系特征及提水作用的影响
沈玉芳1, 李世清1
西北农林科技大学 黄土高原土壤侵蚀与旱地农业国家重点实验室
摘要:
【目的】研究施肥深度对不同水分条件下2个不同品种冬小麦根系提水作用的影响,为制定旱地作物水分管理策略提供科学依据。【方法】以抗旱型长武134(CW134,R)和水分敏感型西农979(XN979,S)冬小麦为试验材料,采用自行设计的上下分层隔离式土培箱装置(分为上室(0~20 cm)和下室(20~60 cm)),设2个水分处理,分别为上层中度水分胁迫(M,上室土壤水分含量为田间持水量的55%~60%,下室为70%~75%)和上层重度水分胁迫(D,上室为田间持水量的35%~40%,下室为70%~75%);对CW134设不施肥(N)、上层施肥(U)、下层施肥(L)3个施肥处理,对XN979仅设上层施肥(U)1个施肥处理,通过时域反射计(TDR)对不同处理的土壤含水量进行控制和观测。研究不同水分条件下,施肥深度对不同品种冬小麦根系提水作用、土壤体积含水量、耗水量、籽粒产量、水分利用效率的影响。【结果】品种和施肥深度显著影响不同水分条件下冬小麦根系长度(RL)、根系表面积(RSA)和根系体积(RV)(P<0.05)。M和D条件下,上层施肥处理冬小麦CW134的RL、RSA和RV分别较XN979显著增加。2个冬小麦整个生育期提水量变化均呈单峰状,除不施肥处理根系提水量在灌浆期达到最大外,其余施肥处理提水量均在扬花期达到最大。M条件下上层处理冬小麦CW134的土壤体积含水量在23:00左右开始上升,至第2天凌晨01:00-05:00均保持高水平,随后又开始迅速下降;而XN979土壤体积含水量只在01:00-03:00出现峰值,随后也迅速下降。D条件下上层施肥处理CW134和XN979土壤体积含水量变化与M条件下类似,只是CW134的土壤体积含水量在03:00-05:00出现峰值。冬小麦全生育期根系提水总量及作物水分利用效率受作物品种、水分处理和施肥深度共同影响,表现出一定的显著性差异。与M相比,D条件下CW134和XN979的全生育期提水总量均降低,但相同水肥条件下CW134生育期根系提水总量、水分利用效率高于XN979。【结论】在旱作农业中可利用抗旱型冬小麦品种较发达的根系和较高的生育期提水作用来充分发掘深层土壤水分;施肥深度也可以调节作物根系分布特征及提水作用,能进一步促进作物对有限水分的高效利用。
关键词:  根系提水  水分利用效率  水势梯度  施肥深度  作物品种
DOI:
分类号:
基金项目:国家自然科学基金项目 (41671307,50809068);国家重点研发计划项目(2017YFD0201807);陕西省自然科学基金项目 (2017JM3011)
Effect of fertilization depth on root characteristics and hydraulic lift of winter wheat under different water treatments
SHEN Yufang,LI Shiqing
Abstract:
【Objective】This study investigated the effect of fertilization depths on root morphological characteristics and hydraulic lift of two wheat varieties under different water treatments to provide basis for design water management strategies for dryland crops.【Method】Three fertilization depths of upper layer (U),lower layer (L) and no fertilizer (N) were set with two crop varieties of Changwu 134 (CW134) and Xinong 979 (XN979).Root systems were grown in two soil compartments including a drier upper layer and a wetter lower layer,and moderate water stress (M) and severe water stress (D) were set in the upper layer.The soil volumetric water content was measured in the upper soil layer by a time domain reflectometer (TDR).【Result】Varieties and fertilization depths had significant effects on root length (RL),root surface area (RSA) and root volume (RV) under different water conditions (P<0.05).Under M and D treatments,CW134 had significantly higher RL,RSA and RL than XN979.The soil volumetric water content was maximal during the blooming stage under U and L treatments,but it peaked during the grain filling stage under N treatment.Under M treatment,for CW134,water content in the upper layer increased from 23:00,reached and kept the peak from 01:00 to 05:00 the next day,and declined rapidly.For XN979,it peaked only from 01:00 to 03:00 the next day before decrease. Under D treatment,water content in the upper layer had the same trend for CW134 and XN979,except it peaked only from 03:00 to 05:00 the next day for CW134.The total amount of hydraulic lift and water use efficiency varied significantly for different varieties,water potential gradients and fertilization depths. The hydraulically lift of CW134 and XN979 under D treatment was lower than under M treatment.But under U treatment,CW134 had higher total amount of hydraulic lift and water use efficiency than XN979 under M and D treatments.【Conclusion】Drought resistant varieties with more developed roots and higher hydraulic lift are better for fully excavating deep soil moisture in rained agriculture.The regulation of fertilization depth would further improve water use efficiency.
Key words:  root hydraulic lift  water use efficiency  water potential gradients  fertilization depth  crop varieties