Temporal and spatial variation of morpho-physiological characteristics of spring maize under mulched drip irrigation in northeastern China

Context Leaves at different heights in a canopy have differential roles on photosynthetic characteristics and yield but have not been compared systematically under plastic film mulching with drip irrigation. Aims To determine the temporal and spatial variation of morpho-physiological characteristics in relation to the benefit of mulched drip irrigation in spring maize growth. Methods Field experiments were conducted in northeastern China during 2017 and 2018 that included mulched drip irrigation (MD), non-mulched drip irrigation (ND), and traditional non-mulched rain-fed (CK) treatments. Key results MD significantly increased lower leaf area by 13.1–62.3%, upper leaf N content (N mass) by 6.3–13.0%, and upper leaf photosynthetic capacity (A max) and maximum carboxylation rate (V cmax) by 13.4–42.3% and by 4.7–11.6%, respectively. There were close correlations between leaf physiological parameters (N mass , carbon isotope discrimination (Δ), A max , and V cmax), and also between morphological parameters (leaf area (LA) with leaf mass per area (LMA), and LMA with leaf dry matter content (LDMC). As for time scale, leaf morphological parameters (LA, LMA, and LDMC) in the reproductive stage (R-stage) were higher than those in the vegetative stage (V-stage), while physiological parameters (N mass , A max , and V cmax) were higher in the V-stage. This study indicated that MD treatment increased the photosynthetic area of lower leaves and the photosynthetic capacity of upper and middle leaves compared with non-mulched rainfed CK. In addition, an increase of net radiation absorbed by the canopy in MD was likely to correspond to a higher net photosynthetic rate, which was beneficial to yield accumulation in the treatment. Conclusions This study provided relevant information for the simulation of water and carbon flux under mulched drip irrigation. Implications The research explained that the morpho-physiological characteristics of leaves at different canopy heights played different role on affecting maize yields under plastic film mulched drip irrigation.