Effects of Plastic Mulch on the Radiative and Thermal Conditions and Potato Growth under Drip Irrigation in Arid Northwest China

Drip irrigation and plastic-film mulch are useful water-saving tools for potato (Solarium tuberosum L.) production in arid Northwest China. Effects of the radiative and thermal conditions produced by the plastic-film mulch on potato growth can be positive or negative. The objective of this study is to know how radiative and thermal conditions and potato growth are affected by the two most commonly used plastic-film mulches (transparent and black) to efficiently use the positive effects of the plastic-film mulch. Field experiments were conducted at the experimental station located in Wuwei, Gansu Province to explore the effects of transparent mulch (TM), a non mulched check (NM), and black mulch (BM) on the net radiation (Re), soil heat flux (G), soil temperature, and potato growth under surface drip irrigation during different plant development stages in 2014 and 2015. Results indicated that the daily integral Re in the BM treatment was greater than in the TM treatment, while the amplitude of G in the BM treatment was lower than in the TM treatment. The BM treatment had 3.0 and 3.9 degrees C greater maximum mulch surface temperature than the TM treatment and had greater longwave radiation on the canopy emitted from the mulch surface. The differences in Re, G, and soil temperature among the treatments diminished with plant canopy enlargement. The potato plant height rankings were BM > TM > NM. The BM treatment had 26% higher jumbo plus large tuber yield than the TM treatment in 2014. Compared with the BM treatment, the TM treatment had the similar potato yield but 9% and 8% less evapotranspiration in 2014 and 2015. The results suggested that the black plastic-film mulch was more suitable for large potato tuber production, while the transparent plastic-film mulch was favorable for water-saving.