不同量秸秆覆盖对春玉米光合生理的影响

Effects of Cropping Systems Using Straw Mulching on Photosynthetic Physiology of Spring Maize(Zea mays L.) During Different Rates

为了探明不同量秸秆覆盖对春玉米全生育期光合特性的影响机理,2007—2009年在陕西合阳县西北农林科技大学旱农试验站,以传统耕作为对照(CK),设置玉米秸秆覆盖量分别为4500(S1)、9000(S2)、13500kg.hm-(2S3)的定位试验。结果表明,各覆盖量处理春玉米叶片群体净光合速率(Pn)、蒸腾速率(T)r和气孔导度(GS)在2008和2009年均表现出协同变化趋势,随覆盖量的递增,Pn、Tr、GS、叶片水分利用效率(WUE瞬时)、PSⅡ潜在活性(Fv/F0)、PSⅡ最大光化学效率(Fv/Fm)和光化学萃灭系数(qP)呈依次升高趋势,其中,S1和CK处理的Pn在2008—2009年均呈"单峰型"曲线变化特征,峰值出现在拔节期;S2和S3处理则表现为"双峰型"曲线变化特征,峰值分别出现在拔节期和孕穗期,且前者高于后者。S1、S2和S3处理2008年籽粒产量较CK分别显著增产7.65%、16.19%和17.84%(P<0.05)。2009年各处理籽粒产量增长趋势和2008年一致,但增幅整体低于2008年,统计分析表明,S3处理光合特性及籽粒产量整体优于S2,但两者间无显著差异(P>0.05)。以上结果表明,不同量秸秆覆盖措施均能通过改善春玉米不同生育时期光合特性,达到增产目的,但从有利于生产实际及提高经济效益来看,渭北旱塬乃至其他同类生态区(春玉米生育期降水量低于390mm)进行玉米整株秸秆覆盖时推荐选择9000kg.hm-2的覆盖量。

A field experimen（t2007—2009）was conducted at the Dry Farming Base of Northwest A F University,Heyang County,Shaanxi Province,China.We evaluated the effects of various treatments at different straw mulching rates on photosynthetic physiologies of spring maize（Zea mays L.）.Four treatments were tested：conventional tillage（CK）and maize straw mulching at rates of 4500 kg.hm-（2S1）,9000 kg.hm-（2S2）and 13 500 kg.hm-（2S3）.The results showed that there was a coordinated variation trend of net photosynthetic rate（Pn）,transpiration rate（T）rand stomatal conductance（GS）in 2008—2009.The Pn,Tr,GS,leaf water use efficiency（WUEinstantaneou）s,PSⅡ potential activity（Fv/F0）,PSII maximal photochemical yield（Fv/Fm）and photochemical quenching coefficien（tqP）of S1,S2 and S3 were higher than that of the CK,and it increased with the rates of straw mulching,The Pn of S1 and CK showed a＂single peak＂curve in 2008—2009,the peak appeared during the jointing stage;However,which of S2 and S3 showed a ＂double peak＂curve,with the peak during the jointing and booting stage,respectively,and the former was higher than the latter.Grain yields of S1,S2 and S3 were increased by 7.65%,16.19% and 17.84%,respectively,compared with CK in 2008,Similar variations were seen for grain yields in 2009,however,the increasing rate of grain yields in 2009 was less than in 2008.The variance analysis showed that the photosynthetic capacity and grain yield of S3 were higher than the S2,whereas there was no significant difference between S3 and S2（P0.05）.It was concluded that the treatments of different straw mulching rates were beneficial for improving the photosynthetic characteristic of spring maize,and had higher grain yields than the CK,Our findings suggest that farmers should adopt rational technologies with straw mulching to obtain the optimal effects in terms of increased crop photosynthetic capacities and grain yields,taking into account the actual production and economic benefit.This technique would be appropriate for straw mulching at rates of 9000 kg.hm-2 in Weibei Highland area,China,and the above results might make for other dryland farming regions throughout the world,where the precipitation is below than 390 mm during the spring maize growth period.