Chinese Journal of Agrometeorology ›› 2018, Vol. 39 ›› Issue (11): 702-714.doi: 10.3969/j.issn.1000-6362.2018.11.002

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Coupling Effects of Water-Saving Irrigation and Shading Intensity on Growth and Development for Rice

LI Rui, LOU Yun-sheng, ZHANG Zhen, MA Li, LI Jun   

  1. 1.Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China; 2.Jiangsu Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044
  • Online:2018-11-20 Published:2018-11-13

Abstract:

A field experiment was conducted to reveal the coupling effects of water-saving irrigation and shading intensity on rice growth and phenological period. Irrigation was designed with 2 levels, conventional irrigation (F, flooding with 5cm water depth layer) and water-saving irrigation (W, wetting without water layer); shading intensity was set at 3 levels, control (CK, natural light source without shading), light shading (S1, single layer shading, photosynthetically active radiation decreased by 60%) and heavy shading (S2, double layer shading, photosynthetically active radiation decreased by 90%). Rice growth parameters were measured in main stages, tillering, jointing, heading, filling and maturing, which included plant height, leaf area index (LAI), chlorophyll content (SPAD value), and water content in single ear as well as canopy hyperspectral data. Using canopy hyperspectral data to extract the enhanced vegetation index (EVI) time series, heading date was predicted by denoising through spline interpolation and wavelet filtering. The results showed that with higher shading intensity, leaf area index and SPAD value decreased, and phenological periods delayed. Water-saving irrigation inhibited plant height and SPAD value of rice, promoted leaf area index under shading conditions. Water-saving irrigation advanced phenophase and shortened phenological periods of rice under shading conditions. Under the same shading conditions, the spectral reflectance on rice canopy was higher in water-saving irrigation (W) than that in conventional irrigation (F) at jointing stage and heading stage, but higher in conventional irrigation (F) than in water-saving irrigation (W) at filling stage and maturity stage. The denoised EVI time series were used to predict heading date in rice, with prediction accuracy being 97%, and extremely significant correlation (P < 0.01).

Key words: Water-saving irrigation, Shading intensity, Rice, Growth, Phenophase