Use of Clinoptilolite to Enhance Rice Sink–Source Traits and Water Productivity Under Alternate Wet–Dry Irrigation

The purpose of this study was to improve the water and fertilizer use efficiency of rice in semi-arid area. A field experiment was conducted to study the water-saving and fertilizer-reducing effects of clinoptilolite (Z) in water-saving irrigated paddy fields and to clarify the relationships between sink–source traits and rice yield. Z coupled with alternate wetting and drying (AWD) irrigation showed increased water saving by 4.8–11.4%, and the Z&AWD (NAZ) and Z&AWD with 25% less phosphorus (P) treatments (LPAZ) significantly increased water productivity by 15.5% on average. The stage in which Z had the most pronounced effect under AWD on dry matter (DM) accumulation was between 30 and 60 days, while under continuously flooded (CF) irrigation, Z had the greatest effect after 60 days, indicating that Z coupled with AWD irrigation was conducive to the DM increase at the vegetative growth stage. LPAZ and NAZ showed lower average nitrogen (N) acccumlation rate and higher grain-filling duration. The principal component analysis indicated the larger N accumulation in early-stage and longer N accumulation duration were conducive to higher grain-filling rate and rice grain yield. To maximize the yield-increasing effect and optimize grain-filling parameters, effective nitrogen fertilizer managements should guarantee the N accumulation “duration” and “stability,” and improve the nitrogen accumulation “amount” in early stage. Clinoptilolite and AWD with 25% less P treatments led to greater, longer, and more stable N accumulation, which saved irrigation water, phosphorus fertilizer, and improved production efficiency.