秸秆集中掩埋还田深度对二化螟幼虫越冬存活率和出土规律的影响

为研究秸秆集中掩埋还田深度对稻秆内二化螟越冬存活率和春季田间出土行为的影响,在2010年3月至6月、2010年11月至2011年6月、2011年3月至6月设置秸秆春耕还田和秋播还田试验,均设集中掩埋深度5 cm、20 cm、35 cm、50 cm 4个处理,以常规覆盖还田为对照。结果表明:秸秆掩埋还田深度与二化螟越冬存活率呈显著负相关,掩埋越深二化螟存活率越低,还田深度超过20 cm时,幼虫死亡率达60%以上,秸秆春耕还田二化螟越冬存活率比秋播还田低。秸秆掩埋还田二化螟越冬幼虫出土历期最长达85 d(2010年秸秆秋播还田),最短是没有幼虫出土(2011年秸秆春耕还田)。秸秆掩埋还田幼虫出土高峰主要集中在5∶00～7∶00和20∶00～22∶00,而秸秆覆盖还田幼虫出土高峰主要集中在12∶00～14∶00。以上结果说明秸秆集中掩埋还田深度影响二化螟越冬幼虫存活率和其春季田间出土行为。

Effects of burial depth of straw returned to soil on survival rate and emergence behavior of Chilo suppressalis over-wintering larva

To study the effects of straw burial depth of straw returned to soil on survival rate and unearthed behavior of Chilo suppressalis over-wintering larva,five treatments,including four burial depths(5 cm,20 cm,35 cm,50 cm) treatments and straw covered onto the soil surface as control,were set.The correlation between straw burial depth and larvae survival rate was significantly negative,the deeper the depth,the lower the survival rate.The mortality of larvae was over 60% when straw burial depth exceeded 20 cm.The larvae survival rate in the soil with straw returning in spring was lower than that in fall.In straw buried treatments,the longest duration of larvae emergence was 85 d,and peak was at 5∶00-7∶00 and 20∶00-22∶00,while in control,the peak appeared at 12∶00-14∶00.