Effects of black plastic film mulching on soil temperature and humidity in root zone and photosynthetic characteristics of rainfed maize

Improving soil environmental conditions may help maximize crop productivity while delaying the senescence of maize. Plastic film mulching has been used for soil moisture conservation, and it is now becoming a well-evolved high yield technique for agriculture in rainfed dry land. This study included 3 treatments: black plastic film mulching (BFM), white plastic film mulching (WFM), and bare land without plastic film mulching (BL). The aims of this study were to investigate the changes of soil temperature and water content under different treatments in a dry and semiarid area, and the effects of black plastic film mulching on yield, yield components and leaf photosynthetic characteristics of maize (Zea mays L.). Maize (Shandan 609) was planted in 2012 and 2013 at the dryland maize experimental field of the Northwest A&F University, in the northwestern China (34°59'N, 107°38'E). Soil temperature at 5, 10 and 15 cm depth was measured and soil moisture at 0-200 cm was determined for water storage calculation based on water balance equation. In addition, measurements also included net photosynthetic rate, transpiration rate, water use efficiency of leaf, electron transport rate, quantum yield, photochemical quenching coefficient of photo-system II, relative green leaf area at maturity, cholorophyll content at maturity, mean and maximum senescence rate. The results showed that the daily soil temperature was the highest for the WFM among the 3 treatments. The BFM also could increase soil temperature but the effect was lower than the WFM. The maximum daily soil temperature of the BFM was 2.3, 1.2 and 1.6℃ lower than that of the WFM in 2012 and 1.8, 0.8 and 1.0℃ in 2013, respectively (P<0.05). The minimum daily soil temperature was not significantly different between the mulching treatments (P>0.05). In 0-140 cm, the water storage was not significantly different between the mulching treatments (P>0.05), both significantly higher than the BL (P<0.05). The mulching treatments could increase the photosynthetic characteristics and the effect was the best in the BFM, especially after the silking stage. Leaf senescence of maize after the silking stage in the WFM and BL treatment appeared earlier than the BFM. The occurrence time of leaf senescence of BFM was delayed, and its leaf senescence rate after the silking stage was significantly lower than BL. The chlorophyll content of leaf at maturity in the BFM was significantly 11.7% and 45.5% higher than the WFM and BL, respectively. The photosynthetic ability of maize in black plastic film mulching treatment was high. The water consumption of the BFM and WFM was significantly lower than the BL. The water use efficiency of the former was significantly higher than the latter. Among the treatments, the yield was the highest in the BFM (P<0.05). The yield of maize in the black plastic film mulching treatment was increased by 10.4% and 22.1% than white plastic film mulching treatment and bare land treatment, respectively. Therefore, black plastic film mulching could delay leaf senescence of maize after the silking stage and increase yield in rainfed farming area. © 2017, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.