覆盖对西北旱地春小麦旗叶光合特性和水分利用的调控

Regulation of mulch conditions on photosynthesis and water utilization of spring wheat in northwest semi-arid area of China

2015—2016年在西北黄土高原半干旱区进行大田定位试验,以‘陇春35号’为试验材料,设全膜覆土穴播(PMS)、全砂覆盖穴播(SM)和露地穴播(CK)3个处理,分析旗叶光合特性、春小麦耗水特性和产量构成因子之间的关系.结果表明:PMS和SM在0～300 cm土层的土壤贮水量在灌浆前分别较CK提高47.8和31.6 mm,灌浆期均较CK降低15.6 mm.PMS和SM提高春小麦挑旗-抽穗期和扬花-灌浆期的土壤耗水.PMS和SM的叶面积指数分别较CK提高59.0%～73.7%和40.1%～52.7%,叶片SPAD值分别较CK提高3.5%～28.4%和2.9%～23.9%.PMS的光合速率和气孔导度在春小麦挑旗、抽穗、扬花期分别较CK提高23.5%、33.0%、17.7%和32.6%、76.4%、66.9%,灌浆期分别较CK降低26.2%和16.4%;PMS和SM的气孔限制值在抽穗、扬花、灌浆期分别较CK降低14.6%、23.9%、22.3%和25.7%、29.8%、17.4%.叶片瞬时水分利用效率PMS在挑旗期较CK提高57.8%,扬花期降低11.2%.PMS的表观量子效率在抽穗、扬花期分别较SM和CK增加22.6%、18.7%和26.8%、14.3%.PMS和SM春小麦的株高和产量构成因子均显著高于CK,且在干旱年份增幅较大;PMS的产量较CK和SM分别提高36.2%和8.7%,水分利用效率分别提高9.4%和3.4%.因此,PMS和SM提高了小麦灌浆前土壤贮水,加剧了挑旗到抽穗和扬花到灌浆期的耗水,提高了小麦叶片SPAD值和叶面积指数,增强了小麦灌浆前旗叶光合功能,促进"库"的建成和同化物的转运,实现增产和水分高效利用.PMS在丰水年份的增产潜力和干旱年份的适应能力比SM更强.

A field experiment was conducted from 2015 to 2016 in the northwestern Loess Plateau, China, to analyze the relationships among flag-leaf photosynthetic characteristics, water-consumption characteristics, and yield components of spring wheat (Triticum aestivum ‘Longchun 35’). There were three treatments: whole-field plastic mulching (PMS), sand mulching (SM), and uncovered (CK). The results showed that soil-water storage levels at 0-300 cm of soil profile before wheat filling under PMS and SM treatments were greater than that in CK by 47.8 and 31.6 mm, respectively, while that under PMS was lower than CK by 15.6 mm at the filling stage. Water consumption under PMS and SM increased in the flagging-heading and flowering-filling stages compared with the CK. Leaf area indices under PMS and SM were increased by 59.0%-73.7% and 40.1%-52.7%, respectively, and leaf SPAD values were increased by 3.5%-28.4% and 2.9%-23.9%, respectively, compared with CK. The net photosynthetic rate of PMS was increased by 23.5%, 33.0% and 17.7% at the flagging, heading, and flowering stages. The corresponding stoma-tal conductance rate was increased by 32.6%, 76.4% and 66.9%, respectively. Net photosynthetic and stomatal conductance rates at the filling stage were decreased by 26.2% and 16.4%, respectively. At the heading, flowering, and filling stages, stomatal limitation values in PMS were decreased by 14.6%, 23.9% and 22.3%, respectively, and by 25.7%, 29.8% and 17.4%, respectively in SM. The instantaneous water-use efficiency of spring wheat in PMS was increased by 57.8% at the flagging stage and decreased by 11.2% at the flowering stage. At the heading and flowering stages, the apparent quantum efficiency was increased by 22.6% and 18.7% in PMS, and by 26.8% and 14.3% in SM, respectively. Plant height and yield component indices in PMS and SM were significantly greater than that in CK, with the enhancement being greater than that in dry years. Grain yield was increased by 36.2% and 8.7% and water-use efficiency increased by 9.4% and 3.4% in PMS and SM, respectively. PMS and SM treatments increased soil water storage before the pre-filling stage of wheat, aggravated water consumption during the flagging-shooting and flowering-filling stages, resulting in greater SPAD values and leaf area indices, which promoted the photosynthetic functions of flag leaves, facilitated sink formation and photosynthetic assimilate transportation, resulting in increased grain yields and water use efficiency of spring wheat. The effects of PMS treatment were more remarkable than those of SM in terms of increasing spring wheat’s yield potential in wet years and adaptability in dry years.