The Impact of Insect-Proof Screen on Microclimate, Reference Evapotranspiration and Growth of Chinese Flowering Cabbage in Arid and Semi-Arid Region.

Despite the steadily increasing area under protected agriculture there is a current lack of knowledge about the effects of the insect-proof screen (IPS) on microclimate and crop water requirements in arid and semi-arid regions. Field experiments were conducted in two crop cycles in Ningxia of Northwest China to study the impact of IPS on microclimate, reference evapotranspiration (ET₀) and growth of Chinese Flowering Cabbage (CFC). The results showed that IPS could appreciably improve the microclimate of the CFC field in the two crop cycles. During the first crop cycle (C1), compared with no insect-proof screen (NIPS) treatment, the total solar radiation and daily wind speed under the IPS treatment were reduced by 5.73% and 88.73%. IPS increased the daily average air humidity, air, and soil temperature during C1 by 11.84%, 15.11% and 10.37%, respectively. Furthermore, the total solar radiation and daily wind speed under the IPS treatment during the second crop cycle (C2) were markedly decreased by 20.45% and 95.73%, respectively. During C2, the daily average air temperature and air humidity under the IPS treatment were increased slightly, whereas the daily average soil temperature was decreased by 4.84%. Compared with NIPS treatment, the ET₀ under the IPS treatment during C1 and C2 was decreased by 6.52% and 21.20%, respectively, suggesting it had great water-saving potential when using IPS. The plant height, leaf number and leaf circumference of CFC under the IPS treatment were higher than those under the NIPS treatment. The yield under the IPS treatment was significantly increased by 36.00% and 108.92% in C1 and C2, respectively. Moreover, irrigation water use efficiency (IWUE) was significantly improved under the IPS treatment in the two crop cycles. Therefore, it is concluded that IPS can improve microclimate, reduce ET₀, and increase crop yield and IWUE in arid and semi-arid areas of Northwest China. [ABSTRACT FROM AUTHOR]