Growth and yield formation of rice (Oryza sativa L.) in the water-saving ground cover rice production system (GCRPS)

A new water-saving 'Ground Cover Rice Production System' (GCRPS) was evaluated in 2001 and 2002 near Beijing, North China. Using GCRPS, lowland rice was cultivated without a standing water layer during the entire growth period and plots were irrigated when soil water tension was below 15 kPa (approximately 90% water holding capacity). In order to prevent soil evaporation, the soil surface was covered with 14 mu m thick plastic film (GCRPS(Plastic)) or mulched with straw (GCRPS(Straw)). In a third GCRPS treatment the soil was left uncovered (GCRPS(Bare)). These treatments were compared with lowland rice cultivated under traditional paddy conditions (Paddy control). In an additional treatment with bare soil, one aerobic rice variety was cultivated. Compared to Paddy control, only 32-54% of irrigation water was applied in GCRPS treatments. Plants in GCRPS were smaller, developed fewer panicles and had a smaller leaf area index compared to Paddy control. Yield was significantly less in GCRPS(Bare) and GCRPS(Straw) compared to Paddy control in both years, while yield in GCRPS(Plastic) was only 8% less than the Paddy control yield in 2002. Water-use efficiency (WUE, gram grain yield per litre water input) in GCRPS(Plastic) was higher (0.35) than in Paddy control (0.23). Grain yield was highly significantly correlated with maximum leaf area index and leaf area index duration. Among yield components, the number of productive tillers had the greatest positive effect on yield, while the number of grains per panicle, thousand-grain weight and harvest index remained almost unaffected. Under uncovered condition, the aerobic rice variety had a significantly higher harvest index (HI), yield, and WUE compared to the lowland rice variety (GCRPS(Bare)). The experiment demonstrates that GCRPS has potential to save substantial amounts of water at relatively minor yield penalties, if stress factors such as low soil temperature, water deficit, and nutrient deficiencies during the vegetative growth stage are avoided by suitable management practices. (c) 2005 Elsevier B.V. All rights reserved.