Responses of soil moisture and photosynthetic characteristics to mulching materials and ridge-to-furrow ratios in rapeseed fields in southwest dryland of China

Abstract

In order to deal with the frequent seasonal drought and improve water use efficiency and crop photosynthetic efficiency in drylands of southwest China, a field experiment was conducted to investigate the effects of different mulching materials (common white film, common black film, biodegradable film and no film) and ridge-to-furrow ratios (40 cm:40 cm and 40 cm:80 cm) on soil water storage, as well as photosynthetic characteristics, fluorescence parameters and chlorophyll relative content (SPAD) of rapeseed, with the flat planting as the control. The results showed that the average soil water storage under different mulching materials followed the order: ridge with common black film (BR) ≈ ridge with common white film (WR) ≈ ridge with biodegradable film (BDR) ＞ ridge with no film (NR) ＞ flat planting (FP). Meanwhile, ridge-to-furrow ratios did not affect soil water storage. The net photosynthetic rate, stomatal conductance and fluorescence para-meters (Fm, Fv, Fv/Fm, Fv/Fo, qP and qN) of rapeseed under ridge-furrow with film mulching was higher than those under flat planting. Compared with control, SPAD value was improved by 6.1%, 8.6%, 8.5% and 3.6% under WR, BR, BDR and NR, while instantaneous water use efficiency (IWUE) was increased by 18.3%, 11.4%, 16.3% and 10.4% under those treatments, respectively. Rapeseed yield under BR, WR and BDR was significantly higher than that in control, while NR did not increase yield. The treatment of ridge with common black film + 40 cm:40 cm as ridge-to-furrow ratio could gain the highest economic benefit. Ridge-furrow planting of rainfall harvesting could improve soil moisture, increase crop photosynthetic capacity, and raise yield and economic income in rapeseed fields in drylands of southwest China.