西北旱地春小麦不同覆盖措施的温度和产量效应

Effect of mulching method on soil temperature and grain yield of spring wheat in rainfed agricultural areas of northwestern China

在西北半干旱雨养条件下,以春小麦为材料,研究了夏季覆膜(T1)、秋季覆膜(T2)、春季覆膜(T3)、小麦碎秆覆盖(T4)、小麦整秆覆盖(T5)、夏季覆膜+麦秆还田(T6)和无覆盖对照(CK)7个处理间0—20 cm土壤温度、产量和重要农艺指标的差异。结果表明:处理间在不同生育时期、不同土层的土壤温度存在显著差异。生育时期间比较,处理间土壤温度差异以播种期—分蘖期最大、蜡熟期—成熟期次之、拔节期—灌浆中期较小;土层间比较,处理间土壤5 cm处的温度差异依次大于10 cm、15 cm、20 cm处。T6在各时期、各土层均表现出突出的增温效应,全生育期土壤平均温度较CK高0.57℃,以成熟期、播种期及分蘖期增温效果较大;其它覆盖处理存在增温和降温的双重效应,增温效应覆膜>秸秆覆盖,而降温效应则秸秆覆盖>覆膜,各处理的32个土壤温度测试点中,增温点次以T4最少(仅有9个),降温点次为23个,且T4降温幅度最大,全生育期0—20 cm土壤平均温度较CK低0.63℃,降温效果在播种期和分蘖期尤为突出。覆盖处理全生育期土壤平均温度表现为覆膜>CK>秸秆覆盖。温差最高值出现在分蘖期土壤5 cm处的T6与T4间,T6高出T44.23℃。T6可以平抑生育期间土壤温度的变化,其它5个覆盖处理则加剧土壤温度的波动,以T4处理的土壤温度波动最明显(CV为32.4%)。处理间产量、单位面积穗数、穗粒数间差异显著,而千粒重差异不显著。无论覆膜还是秸秆覆盖,都较CK穗粒数显著增加(17.4%—36.3%)。除T5较CK显著减产14.1%外,其它覆盖处理均较CK显著增产21.7%—37.3%,其中以全膜覆土穴播基础上的秋季覆膜(T2)增产最显著,适宜在西北旱地春小麦产区推广应用。土壤温度主要影响营养生长,拔节—开花期0—20 cm的土壤温度与株高高度正相关(0.77*—0.92**),但覆盖引起土壤温度的变化最终对西北旱地春小麦产量没有关键影响。

This study determined the effects of mulching method on soil temperatures in the 0—20 cm soil layer,and grain yield of spring wheat（ Triticum aestivum L.） in a semiarid rainfed agricultural area of northwestern China. The experiment was conducted at Tongwei Research Station,Gansu Agricultural University（ 34°55＇N,104°57＇E） in 2012. The following 7treatments were evaluated： plastic film mulch applied in summer（ T1）,plastic film mulch applied in autumn（ T2）,plastic film mulch applied in spring（ T3）,mulching with chopped wheat straw（ 5 cm in length） on the soil surface in summer（ T4）,mulching with whole wheat straw in summer（ T5）,T1 in combination with harvested wheat straw returned to the field（ T6）,and control（ no mulching,CK）. Soil temperatures were measured and recorded at 32 points in each treatment. Soil temperatures differed significantly among mulching treatments,growth stages and soil layers. The largest difference in soil temperature occurred from the sowing to tillering period,followed by the dough stage to maturation period,whereas the smallest differences in soil temperature were in the jointing-middle filling stage. Soil temperature decreased with soil depth in the order 5 cm〉 10 cm 〉15 cm 〉20 cm. Soil temperature in the T6 plots was significantly（ 0.57 ℃） higher than,and this effect was more pronounced in the sowing,tillering,and maturing stages than in the other growth stages. The other five treatments either increased or decreased soil temperatures depending on growth stage and soil layer. Soil temperature was consistently increased by plastic film mulch but consistently decreased by straw mulching. The T4 treatment had 9 points with soil temperatures higher than the CK,and 23 points lower than the CK. Mean soil temperature over the whole growth period was 0.63℃ lower in the T4 treatment than in the CK,with the difference being more obvious at the time of sowing and the tillering stage. Average soil temperatures over the whole growth period were in the order： plastic film mulch CK straw mulching. The highest difference occurred between T6 and T4in the 5 cm soil layer at the tillering stage,with T6being4.23 ℃ higher than T4. The largest variation soil temperature among growth stages was found in the T4 treatment,with a coefficient of variation of 32.4%. Mulching increased the number of kernels per spike by 17.4% to 36.3% compared with the CK. Mulching increased wheat grain yield by 21.7% to 37.3% compared to the CK,with the maximum yield increase being with plastic film mulch applied in the autumn（ T2）. The exception was the T5 treatment which decreased grain yield by 14.1% compared to the CK. It appears that the T2 mulching method is the most suitable for spring wheat production in rainfed agricultural regions of northwestern China. There were highly positive correlations（ r = 0.77＊—0.92＊＊） between soil temperature and plant height at jointing-flowering,but mulching method did not have a significant impact on spring wheat grain yield in the study area.