The physiological and ecological traits of strip management with straw and plastic film to increase grain yield of intercropping wheat and maize in arid conditions

Strip intercropping is a feasible cropping pattern to improve crop productivity via enhancing the stability of farmland ecosystem. Straw returning and plastic film mulch are effective and valuable measures to boost crop productivity in arid or semi-arid regions. It is unknown whether the yield advantage of strip intercropping can be further enhanced by improving photosynthetic characteristics when applied synchronously with straw returning and plastic film mulch measures. A field experiment on wheat-maize intercropping system was conducted at strip management with straw and plastic film, and photosynthetic characteristics, leaf and soil water potential, and grain yield were determined. The results showed that the SPAD value of wheat and maize leaves with NTSM/NTP (no-tillage with wheat straw mulch in wheat strips and previous residual plastic film mulch in maize strips) was decreased at the vegetative growth period, a higher SPAD value was maintained at the reproductive growth period, compared to CT/CTP (conventional tillage with no straw returning in wheat strips and annual new plastic film mulch in maize strips), it indicated that NTSM/NTP treatment can maintain high physiological activity of intercropped wheat and maize at their reproductive growth period. NTSM/NTP treatment raised net photosynthetic rate (Pn) and leaf water use efficiency (WUEL) of wheat by 9.0–15.8 % and 4.9–8.8 % from filling (Feekes 11.0) to doughing (Feekes 11.2) stage, and raised both indexes of maize by 11.5–25.5 % and 4.7–14.8 % from milking (R3) to doughing (R4) stage, with little effect on transpiration rate (Tr), in comparison to CT/CTP, respectively. NTSM/NTP treatment kept relatively high leaf and soil water potential of intercropped strips, and favorably created a suitable soil moisture environment for enhancing the drought resistance on intercrops. In addition, the value of difference between leaf and soil water potential of wheat and maize in NTSM/NTP treatment was lower than that in CT/CTP treatment at given determining stages, it indicated that NTSM/NTP treatment was beneficial to maintaining the stability of crop water demand and soil water supply for growth of two intercrops. Thus, NTSM/NTP treatment obtained high grain yields, increased by 8.6–11.1 % for intercropped wheat, increased by 16.0–20.2 % for intercropped maize, and increased by 13.8–17.1 % for intercropped wheat plus maize, in comparison to CT/CTP treatment. The improved photosynthetic capacity, optimized leaf and soil water potential, and increased grain yields for intercropped wheat and maize in NTSM/NTP treatment. Therefore, strip intercropping integrated of no tillage with wheat straw and previous residual plastic film mulch can be recommended as the excellent technique to coordinate the contradiction between water shortage and high grain yield in arid irrigated regions.