Guangzhou city, located in the southern part of China, experiences temperatures above 30°C and heavy showers from June to September. Farmers usually produce vegetables on bare ground during this season, hence the yield and quality of the products are very low. A few varieties of sweet pepper (Capsicum annuum) are cultivated with or without mulches consisting of plastic film or some other materials during the hot season.
In field trials conducted in 1987, the yield of the earlier planting (April 9) was 1/9 of the yield of the later planting (May 18). in the latter, harvest continued from July 28 to October 28, and the yield in August and September was much lower than that of October due to high temperature. The highest yield was obtained by the combination of cheesecloth cover and plastic mulch. The production was 20 times higher than that in the case of bare ground cultivation.
The overall yield in 1988 was slightly lower due to stem rot incidence. Among the cover materials tested on pipe houses, the yield was highest when covering included both cheesecloth and windbreak-net. The yield in the open field was lower regardless of the use of plastic mulch. A hybrid variety from Shanghai showed a higher yield than local varieties of Guangzhou.