CHIANG MAI UNIVERSITY JOURNAL OF NATURAL SCIENCES

Volume 19, No. 03, Month JULY, Year 2020, Pages 350 - 365

The effects of different npk fertilization rates and water regimes on ratooned black glutinous rice

Benyamin Lakitan, Karla K. Jaya, Rofiqoh P. Ria and Badai Morianto

Abstract Download PDF

Ratooned rice crop is a strategy for increasing rice production at short second rice growing season at riparian wetland under unpredictable climatic condition. The objective of this research was to evaluate vegetative growth and potential grain yield in ratooned black glutinous rice exposed to continuous flooding at 3-cm depth, alternate wetting-drying condition, and shallow water table during second rice growing season at riparian wetland. These three water regimes simulate the possibilities of unfavorable conditions, i.e. prolonged rainy season, inconsistent rain distribution, and early transition of rainy-to-dry season. In addition to water regime treatments, the ratooned rice was enriched with three NPK (15-15-15) rates equivalent to 80, 160, 240, and 320 kg/ha. Results indicated that total and productive tillers, leaf and stem dry weight, number of leaves, percentage of filled grain, and grain yield were significantly affected by water regimes; while NPK application rates significantly affected total and productive tillers, number of leaves, and grain yield. Continuous flooding effectively controlled weed outburst during cultivation of ratooned rice. Therefore, it contributed to better rice vegetative growth and grain yield than those exposed to alternate wetting-drying or shallow water table condition. The highest grain yield was found at 320 kg/ha NPK application rate. Number of productive tillers was highly correlated with grain yield (r = 0.8499) while total number of tillers was moderately reliable (r = 0.6334) and can be used as an early predictor for grain yield in ratooned rice.

Keywords

Continuous flooding, Alternate wetting-drying, Shallow water table, Glutinous rice, Riparian wetland.

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