间作小麦光合性能对地上地下互作强度的响应

Response of photosynthetic performance of intercropped wheat to interaction intensity between above-and below-ground

本研究旨在探讨地上地下互作强度对间作小麦光合性能的影响,为进一步揭示间作体系作物产量优势的光合机制提供依据。2015—2017年连续3年在河西绿洲灌区进行田间试验,以小麦间作玉米为研究对象,设置地下部3种互作强度:根系不分隔(完全地下互作处理, W/M)、300目尼龙网分隔(部分地下互作处理, NW/M)和0.12 mm塑料布分隔(无地下互作处理,PW/M),以及地上部高、低玉米密度(M1、M2)2种互作强度,同时设置相应单作处理。结果表明,小麦间作玉米共生前期和后期完全地下互作处理促使小麦净光合速率(P_n)显著提高,且共生后期玉米密度的提高促使完全地下互作效应增强,进一步提高了小麦P_n。小麦间作玉米共生前、中和后期,完全地下互作处理可显著提高小麦叶片气孔导度(G_s)、胞间CO_2浓度(Ci),且玉米密度提高对共生前期完全地下互作处理和部分地下互作处理小麦Gs的增加起到促进作用。在共生前期、后期完全地下互作和部分地下互作处理保持了较低的Tr。间作完全地下互作处理有助于小麦叶日积(LAD)的增加,且随着生育进程的推进,提高比率越大。完全地下互作处理使共生中期间作小麦叶片相对叶绿素含量值(SPAD)显著增加,有利于光合强度的提高。间作小麦具有显著的增产效应,完全地下互作处理中小麦籽粒产量达到相应单作产量的76.8%,具有显著提高间作群体籽粒产量的优势,且地上部互作强度增强有利于完全地下互作处理正效应的发挥。地上地下互作强度是影响间作小麦光合性能的重要因素之一,在生产实践中可通过调节地上地下互作强度的强弱来优化低位作物光合性能。

The purpose of this study is to explore the effects of above-ground and underground interaction intensity of intercropped population on the photosynthetic performance of intercropped wheat and to provide a basis for further revealing the photosynthetic mechanism of crop yield advantage in intercropping system.From 2015 to 2017 wheat intercropping with maize was taken as the research object.Three root separation methods were designed:no root separation(complete below-ground interaction treatment,W/M),300 mesh nylon net separation(partial below-ground interaction treatment,NW/M),0.12 mm plastic cloth separation(no below-ground interaction treatment,PW/M),and tow level maize densities.Meanwhile,the corresponding monocluture was carried out.The results showed that the Pn of intercropped wheat was significantly increased by the complete below-ground interaction treatment during per-symbiotic period and late symbiotic period of wheat/maize intercropping,with the increase of maize density the Pn of wheat increased during late symbiotic period.During per-symbiotic period,mid-symbiotic period and late symbiotic period of wheat/maize intercropping,the complete below-ground interaction treatment can significantly improve the Gs,Ci of intercropped wheat.The increase of maize density can promote the increase of Gs in the complete below-ground interaction treatment and partial below-ground interaction treatment during per-symbiotic period.The Tr of leaves was higher during mid-symbiotic period and late symbiotic period of wheat/maize intercropping without below-ground interaction treatment,while the Tr of leaves remained lower in both stages of complete below-ground interaction and partial below-ground interaction.Complete below-ground interaction treatment was helpful to increase the daily leaf area(LAD)in wheat,with the development of growth process,the increase ratio was larger.Complete belowground interaction treatment significantly increased the SPAD of leaves during mid-symbiotic period,which was beneficial to increase photosynthetic intensity.Intercropped wheat had significant yield-increasing effect.The grain yield of wheat under complete below-ground interaction treatment reached 76.8%of the corresponding single-cropped,which had the advantage of significantly increasing the grain yield of intercropping population.Moreover,the enhancement of above-ground interaction intensity was conducive to the positive effect of complete below-ground interaction treatment.The intensity of above-and below-ground interaction was one of the important factors affecting the photosynthetic characteristics of intercropped wheat.