地上地下互作强度对小麦间作玉米光合特性的影响

针对地上、地下互作对间作群体光合特性影响研究相对薄弱,生产实践中缺乏间作系统精确调控的相关理论依据等问题,本研究于2015—2017年,以小麦间作玉米为对象,通过设塑料布隔根(P,无根间作用)、尼龙网隔根(N,部分根间作用)和不隔根(完全根间作用) 3种根系分隔方式,以及低(M1, 45,000株hm~(–2))、高(M2,52,500株hm~(–2))2个玉米密度,系统分析了地上地下互作强度对间作作物群体光合特性的影响。结果表明,地上地下完全互作可显著增加间作群体的光合势,提高间作玉米的净光合速率,增大间作群体全生育时期的净同化率。与低密度相比,增大玉米密度使间作群体全生育期光合势平均提高12.4%;与尼龙网隔根和塑料布隔根相比,不隔根处理光合势提高了10.3%和29.0%。增大密度使间作玉米净光合速率比低密度平均提高11.2%;不隔根间作玉米生育期净光合速率较尼龙网隔根和塑料布隔根平均提高4.7%和7.7%。玉米密度对间作系统净同化率影响不显著;不隔根处理全生育时期净同化率比尼龙网隔根和塑料布隔根平均提高11.5%和14.8%,生育后期,间作群体的光合势与产量极显著正相关。因此,地上地下协同影响作物群体光合势及间作组分作物的净光合速率,从而影响间作群体的净同化率,可通过增加密度和根间互作来促进协同作用,增加间作系统产出。

Effect of above- and below-ground interaction intensity on photosynthetic characteristics of wheat-maize intercropping

A field experiment of wheat-maize intercropping was conducted from 2015 to 2017, with three root separation treatment adopted to produce the different below-ground interactions: (i) root separation with producing plastic cloth no below-ground interaction (P); (ii) root separation with producing nylon mesh partial below-ground interaction (N); and (iii) no root separation, producing complete below-ground interaction. Two planting densities; M1 and M2 (with 45,000 and 52,500 maize plants per hectare), were employed to create the different above-ground interactions. The above- and below-ground complete interaction significantly improved the leaf area duration (LAD), net assimilation rate (NAR) of the intercropped, and net photosynthetic rate (P_n) of the intercropped maize. Compared with low density treatment, the LAD of high maize density was improved by an average of 12.4%. Compared with nylon mesh and plastic sheet root barriers no root barrier increased LAD by 10.3% and 29.0%. Maize P_n was improved by 11.2% under high density than under low density. No root barrier improved P_n by 4.7% and 7.7% as compared with nylon mesh and plastic sheet root barriers, respectively. There was no significant effect of maize density on NAR of the intercropping system. No root barrier improved NAR by 11.5% and 14.8% as compared with nylon mesh and plastic sheet root barriers, respectively. During the late growth period, grain yield was significantly correlated with LAD. The above- and below-ground interactions synergistically affected LAD and P_n, which influenced NAR of the intercropping system. Therefore, the synergistic effect could be promoted by increasing maize density and above- and below-ground interactions, which would promote the intercropping system productivity.