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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。
In order to find out the mechanism of different amount of straw mulching on the photosynthetic characteristics of spring maize during its whole growth period, 2007-2009 was set up as a control (CK) at the dry-farming experiment station of Northwest A & F University, Heyang County, Shaanxi Province. Corn straw mulching The amount of 4500 (S1), 9000 (S2), 13500kg.hm- (2S3) positioning test. The results showed that the net photosynthetic rate (Pn), transpiration rate (T) r and stomatal conductance (GS) of spring maize leaves showed a synergistic trend in 2008 and 2009 with the different coverage levels. With the increase of coverage, Pn , Tr, GS, Fv / F0, Fv / Fm and qP of leaf water use efficiency (WUE) The peak value of Pn in CK was “unimodal” in 2008-2009, and the peak appeared in jointing stage. The change of “bimodal” curve in S2 and S3 appeared in Jointing and booting stage, and the former is higher than the latter. Compared with CK, the grain yield of 2008, 2008 and 2007 increased by 7.65%, 16.19% and 17.84%, respectively (P <0.05). The trend of grain yield increase in 2009 was the same as that in 2008, but the increase was lower than that in 2008. Statistical analysis showed that the overall photosynthetic characteristics and grain yield of S3 were better than that of S2, but there was no significant difference between them (P> 0.05). The above results show that different amount of straw mulch can improve photosynthetic characteristics in different growth stages of spring maize to achieve the purpose of increasing yield. However, from the point of view of actual production and economic benefits, the Weibei highland and other similar ecological zones Precipitation less than 390mm during the growth period) for corn whole plant straw coverage recommended 9000kg.hm-2 coverage.