秸秆覆盖条件下水分亏缺对春青稞水分利用和产量的影响

提高水分利用效率对发展西藏高海拔地区节水农业至关重要。该文通过小区试验,研究了秸秆覆盖条件下春青稞不同生育期对水分亏缺程度的响应。试验处理包括全生育期充分灌溉处理(对照)以及苗期、拔节期、抽穗期、灌浆期和成熟期水分亏缺处理。结果表明,水分亏缺处理显著降低了春青稞耗水量和耗水强度(P0.05),且其减小程度随着亏缺程度的增加而增大。灌浆期水分亏缺对全生育期作物耗水量的影响最大,其轻、重度水分亏缺处理分别减少全生育期耗水量19.6%和24.2%;在水分亏缺处理下春青稞产量差异不显著。在试验条件下,不同水分亏缺没有导致减产,而水分利用效率提高4.64%~21.85%,节水4.96%~24.24%。当土壤水分下限控制在55%田间持水率时,对春青稞产量及构成没有产生显著不良影响且获得了较高的节水率,表明在西藏高海拔半干旱寒区,可以通过秸秆覆盖农田管理措施,使春青稞获得更大的节水空间。

Effects of water deficit on water use and yield of spring highland barley under straw mulching

Abstract: It is very important to improve water use efficiency for the development of water-saving agriculture in high altitude semi-arid cold region of Tibet. In order to obtain a suitable lower control limit of soil moisture content for irrigation and set up water-saving irrigation regime, the responses of spring highland barley to water deficit level in various growth stages were investigated by a field experiment under straw mulching condition in 2014. Experimental treatments included full irrigation treatment in whole growth period (control) and water deficit treatments that exerted in seedling, jointing, heading, filling, and mature stages respectively. The lower control limit of soil moisture content was 75% of soil field capacity in full irrigation treatment. In water deficit treatments, the lower control limit of soil moisture content was 65% (slight water deficit) and 55% (heavy water deficit) of soil field capacity in the growth stage that water deficit was imposed, and that in the other growth stages was 75% of the soil field capacity. The upper control limit of soil moisture content for irrigation was soil field capacity for all the experimental treatments. The results showed that water deficit treatments in various growth stages significantly decreased water consumption amount and daily water consumption intensity of spring highland barley (P<0.05), and the degree of decrease increased with the increased water deficit level. Mean water consumption intensity all over the whole growth period was 4.9 mm/d with a maximum value of 7.3 mm/d that occurred at heading stage under full irrigation treatment, and the water consumption intensity was 4.0-4.6 mm/d under various water deficit treatments. The effect of water deficit treatment imposed in the filling stage of spring highland barley on crop water consumption amount was biggest and that of water deficit treatment in the heading stage was second in all water deficit treatments. Compared with full irrigation treatment, the water consumption amount of spring highland barley was decreased by 56.4-68.0, 82.1-124.7, 36.0-71.3, 142.2-175.9, and 43.6-48.2 mm, respectively, for the water deficit treatments exerted in seedling, jointing, heading, filling, and mature stages. Water deficit did not significantly affect the ear length, seeds per ear, thousand seed weight, harvest index, and grain yield of spring highland barley. Under the experimental conditions, water deficit treatments exerted in various growth stages did not significantly result in the reduction of grain yield, but water use efficiency was increased by 10.5% and water-saving percentage was 11.7% on average. Water deficit treatment imposed in the filling stage of spring highland barley resulted in a highest water use efficiency of 1.77-1.84 kg/m3 and a biggest water-saving percentage of 19.6%-24.2% in all experimental treatments. In a word, when the lower limit of soil moisture content was controlled at 55% of soil field capacity, water deficit did not significantly affect the yield and its components of spring highland barley, and meanwhile a high water-saving percentage was obtained. This indicates that spring highland barley has a great water-saving potential and possibility if straw mulching management measure is adopted in the high altitude semi-arid cold region of Tibet. The effects of water deficit treatments in multiple growth stages on the growth of spring highland barley need to be studied further.