地膜覆盖对土壤水分和夏薯苗期根系建成的影响

基于覆膜和无膜处理对夏薯土壤相对含水量动态变化影响的研究,通过营养液水培和PEG-6000模拟干旱等方式研究6个甘薯品种在正常供水(模拟覆膜)和梯度干旱(模拟无膜)处理条件下的根系生物学性状。结果表明:覆膜使土壤相对含水量的降低缓慢而避开干旱胁迫的影响,而无膜处理的土壤相对含水量降低迅速。在浇足窝水的情况下,即使20天内无水分补充,覆膜土壤的相对含水量仍能保持在60%以上;而在无膜条件下,栽后6天为夏薯发生干旱胁迫的临界时间,且从轻度干旱胁迫到重度干旱胁迫的过程短,仅2天。不仅如此,与覆膜处理相比,干旱情况下无膜处理的甘薯根长、根投影面积、根表面积、根平均直径、根体积、根鲜重和根干重等指标均显著降低。而品种间比较发现,覆膜情况下色素提取型甘薯根系生长快、根量多,遭遇干旱胁迫后,色素提取型甘薯根系生物学性状降低幅度最大,对水分变化表现更敏感。6个甘薯品种根长、根表面积和根体积主要集中在平均直径大于0.45 mm的不定根上。总之,地膜覆盖有利于减缓土壤水分损耗,促进夏薯早发根、多发根,降低干旱胁迫对根系建成的不利影响。

Effects of Film Mulching on Water Content in Soil and Root Formation of Summer Sweet Potato Seedlings

Based on the influences of film mulching and non -film mulching on dynamic change of rela-tive water content in soil （ RWCS ） , the root biological characters of 6 sweet potato varieties were researched under normal water supply （ stimulating film mulching ） and gradient drought （ stimulating non -film mulc-hing） by hydroponics and treated with PEG -6000.The results showed that RWCS decreased slowly under film mulching treatment , which made sweet potato escaped from drought stress , while that under non -film mulching treatment decreased rapidly .In the case of adequate water supply when transplanting , RWCS would maintain over 60%even though without water supply for 20 days.Under non -film mulching treatment , the sixth day after transplanting was the critical time of drought stress , and the process from mild drought stress to severe drought stress took only 2 days.Compared with film mulching treatment , the root length, projected are-a, superficial area, average diameter, volume, fresh weight and dry weight of the 6 sweet potato varieties sig-nificantly decreased under non -film mulching treatment .Intervarietal comparison showed that the root of pig-ment extraction type sweet potato grew faster and more under film mulching treatment , and its biological char-acters decreased faster when encountered drought stress ,so it was more sensitive to moisture change .The root length, superficial area and volume of the 6 sweet potato varieties mainly located on adventitious roots whose diameter was over 0.45 mm.Above all, film mulching could retard water loss of soil , promote summer sweet potato rooting earlier and more , and decrease negative effects of drought stress on root formation .