水分与玉米秸秆还田对小麦根系生长和水分利用效率的影响

【目的】通过两年的防雨棚微区控水试验,探索秸秆还田和水分调控对小麦根系生长、产量及水分利用效率的影响,为提高秸秆还田效果及推广应用秸秆还田技术提供参考。【方法】试验设玉米秸秆粉碎翻压还田(RS)和秸秆不还田(CK)处理;3种土壤水分处理,分别为田间持水量的50%—55%(干旱处理,D)、60%—65%(轻旱处理,SD)和70%—75%(适宜水分处理,N)。测量土壤水分含量、根干重、根干重密度、根系活力、籽粒产量和水分利用效率等指标。【结果】干旱条件下小麦成熟期的次生根数显著降低,与轻旱和适宜水分处理相比,不同生育时期小麦根系活力均显著降低,0—25 cm土层中的根干重密度在不同的生育时期也基本表现为降低趋势,产量下降幅度分别为4.34%—38.30%和14.30%—36.63%,但土壤贮水消耗量分别显著增加7.92%—25.56%和31.34%—90.72%,水分利用效率分别显著增加12.69%—30.09%和11.83%—32.88%。干旱条件下,与CK处理相比,RS处理在返青期和成熟期的单株次生根数分别提高了17.17%—29.41%和5.60%—27.86%,不同生育时期0—25 cm土层中根干重密度降低,花后根系活力及25—50 cm土层中根干重密度的下降幅度增大,产量和水分利用效率分别显著降低了15.02%—19.52%和7.51%—14.56%。轻旱和适宜水分条件下,与CK处理相比,RS处理提高了不同生育时期的单株次生根数,减缓了小麦花后的根系活力及25—50 cm土层中的根干重密度下降幅度,并且增加土壤贮水消耗量,降低灌溉量及总耗水量,除2013—2014年小麦生长季适宜水分条件下不同还田方式间产量和水分利用效率差异未达显著水平外,秸秆还田处理的产量和水分利用效率分别显著提高了6.09%—9.18%和6.77%—11.13%。另外,秸秆还田方式与水分调控的交互作用显著影响小麦产量和水分利用效率。【结论】在较好的土壤水分条件下(轻旱和适宜水分),秸秆还田对小麦根系生长具有正效应,有利于延缓根系衰老,增加土壤贮水消耗量、产量及水分利用效率,减少灌溉量;而在土壤水分条件较差时进行秸秆还田,小麦产量和水分利用效率显著降低。

Influence of Returning Corn Stalks to Field Under Different Soil Moisture Contents on Root Growth and Water Use Efficiency of Wheat (Triticum aestivum L.)

【Objective】To evaluate the influence of soil moisture and corn stalks returning practice on wheat root growth, grain yield and water use efficiency, a 2-year micro-plot experiment was conducted under rain-proof shelter condition, aiming at provide reference for improving effect and application of stalks returning to field. 【Method】Prior to wheat sowing, corn stalks were cut and incorporated into soil by plowing (stalks returning, RS), with non-stalks returning as control (CK). Both RS and CK were subjected to 50%-55% (Drought, D), 60%-65% (Slight Drought, SD) and 70%-75% (Normal, N) of field moisture capacity, respectively.【Result】The results showed that nodal roots per plant at maturity, root activity, root dry weight density within 0-25 cm soil layer of winter wheat in D treatments at different growing stages were dramatically decreased compared with those in either SD or N treatments, grain yield was decreased by 4.34%-38.30% and 14.30%-36.63%, respectively, though consumption of soil water storage and water use efficiency in D treatments increased by 7.92%-25.56% and 31.34%-90.72%, 12.69%-30.09% and 11.83%-32.88%, respectively. In D treatment, nodal roots per plant were 17.17%-29.41% and 5.60%-27.86% higher than those in CK at re-growing and maturity stages, but root dry weight density within 0-25 cm soil layer at different growing stages was lower in RS treatments than that in CK. The decrement in both root vigor and root dry weight density within 25-50 cm soil layer after flowering was significant higher than those in CK, grain yield and water use efficiency in RS were significantly decreased by 15.02%-19.52% and 7.51%-14.56% compared with that in CK. In SD and N treatment, nodal roots per plant were higher at different growing stages and the decrement in both root vigor and root dry weight density within 25-50 cm soil layer were lower in RS treatments, while irrigation amount and total water consumption were all decreased. Consumption of soil water storage was significantly increased, except for the N treatment in 2013-2014, grain yield and water use efficiency were dramatically increased by 6.09%-9.18% and 6.77%-11.13% compared with those in CK treatments. In addition, the present study also showed a significant interaction both of grain yield and water use efficiency between corn stalks returning and soil moisture conditions.【Conclusion】Corn stalks returning practice reduced irrigation amount, improved grain yield and water use efficiency by conserving soil water storage and improving root physiological function during the whole growing period under normal soil water and even slight drought conditions, but decreased grain yield and water use efficiency under drought condition.