Combination of plastic film mulching and AMF inoculation promotes maize growth, yield and water use efficiency in the semiarid region of Northwest China

Plastic film mulching (PFM) plays a critical role in improving crop production and sustainable development of agroecosystem in semiarid agriculture. Arbuscular mycorrhizal fungi (AMF) can form a mutualistic symbiosis with the vast majority of plant roots and have been shown to contribute to host growth in harsh conditions. Yet, whether the integrated application of PFM and AMF inoculation have an interactive effect on crop growth and production in semiarid regions with poor soil nutrients and water shortage has received rather less attention. Therefore, we performed a two-year field study to investigate the effects of PFM and AMF inoculation on spring maize growth, yield and water use efficiency (WUE). Four treatments, including non-mulching and non-AMF inoculation (CK), plastic film mulching (PFM), arbuscular mycorrhizal fungi inoculation (AMF) and combination of plastic film mulching and arbuscular mycorrhizal fungi inoculation (PAMF), were compared in 2014 and 2015 at Shenmu Country on the semiarid Loess Plateau of Northwest China. Our results indicated that AMF inoculation contributed to increased plant biomass and height, although its effectiveness was lower than PFM alone or combined practice. Compared with the non-mulched control (CK), the mulched treatments significantly increased the average soil water content by 43.2% at the depth of 0-60 cm in 2014 and by 30.3% at the depth of 0-30 cm in 2015. The combination of PFM and AMF inoculation had the greatest soil water content at different soil depths in both years. AMF inoculation significantly improved root mycorrhizal colonization and external hyphal length in both years. Meanwhile, mycorrhizal plants under PFM had significantly greater root tip number and surface area when compared with the control. PAMF treatment had the highest yield and WUE among all treatments. Compared with the CK, PAMF treatment increased the yield and WUE by55.6% and 43.1% in 2014 and by 39.3% and 45.6% in 2015, respectively. Moreover, the mycorrhizal dependency of maize yield was more notable in mycorrhizal plants grown in mulched soils than in bare soils. In conclusion, the combined application of PFM and AMF inoculation is an effective and favorable agricultural practice in nutrition-deficiency soil in semiarid regions of China because of improved root morphological traits and enhanced topsoil water content that increase crop productivity.