Effects of water management on rice characterisitics

Rice (Oryza sativa L.) is adapted to grow both in submerged and aerobic soils. The effects of different water management systems on several characteristics of rice (milling yield, biometric characteristics, nitrogen and amylose content, pasting properties and cooking behavior) were investigated. The effectiveness of Near Infrared (NIR) spectroscopy to provide comprehensive information regarding the effects of water management on the quality traits of rice was also evaluated. Four rice varieties (Baldo, Gladio, Loto and Selenio) were grown in two consecutive harvesting years in three agricultural systems, characterized by a progressively more intensive use of water: dry seeding and delayed flooding (DRY); dry seeding and rotational irrigation (IRR); water seeded and continuous flooding (FLD). NIR spectral data were collected in reflectance mode using a FT-NIR spectrometer. The spectral data were correlated with biometric, chemical and rheological parameters by Principal Component Analysis (PCA) and PLS regression algorithm. Considering the overall dataset, a univocal influence of the water management on rice properties was not found, since the characteristics regarding quality, before and after cooking, seem to be mainly related to the harvest year and variety, in particular to its amylose content. By Principal Component Analysis of NIR spectra it was possible to determine both harvesting year (PC1, PC2; total explained variance of 84%) and rice variety (PC1, PC3; total explained variance of 77%). Moreover, good correlations were found through PLS algorithm for nitrogen content (R2= 0.98), viscoamylographic breakdown (R2= 0.93) and optimal cooking time (R2= 0.89). The NIR spectroscopy has proven to be a reliable and sensitive technique, suitable for evaluating not only chemical indices but also cooking attributes.