A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Agricultural Systems and Engineering, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 2017

A major challenge in rice (Oryza Sativa L.) production is to achieve dual goal of increasing food production and saving water. Alternative wetting and drying has been proposed as an effect water saving strategy for cultivation of rice. The effects of soil moisture and cultivation method under wetting and drying condition on growth and yield of rice were examined in a greenhouse experiment at the Asian Institute of Technology, Thailand during November 2016 to March 2017. The treatment consisted of three varieties (Pathumthani-1, RD57 and RD41), three cultivation methods (DDS, WDS, and TP), and three moisture levels (-5kPa, -15kPa, and -30kPa). Plant height, number of tiller/plant, number of panicle/plant, number of filled grains/panicle, 1000- grain weight, shoot dry weight and grin yield were reduced with decreasing soil moisture level under three-cultivation methods for all three varieties. Reponses of three rice varieties in different moisture levels under different cultivation methods varied significantly. There was different degree of reduction to the growth and yield parameters due to decreasing soil moisture under different cultivation methods for rice varieties. Pathumthani-1 performed better in producing tiller, plant height, panicle number, filled grain, shoot dry weight and yield within three soil moisture levels under three cultivation methods. RD57 also showed the highest plant height, 1000-grain weight and filled grain, but medium shoot dry weight, panicle number and yield. However, RD41 variety showed the lowest plant height, tiller number, panicle number, filled grain,1000-grain weight and yield under all three levels of moisture and cultivation methods. Also among the cultivation method under wetting and drying irrigation DDS and WDS showed better result than TP with different soil moisture levels for three varieties. The result showed that decreasing soil moisture under wetting and drying condition strongly reduced growth and yield parameters within all varieties. Water productivity also was influenced by moisture and cultivation method. High water productivity was found in Pathumthani-1 variety and DDS cultivation method; however, low water productivity was observed for TP with RD41 variety. Water productivity was increased under all three soil moisture levels compared with the flooded condition within three cultivation methods for rice varieties. The result showed that both -5kPa and -15kPa moisture levels increased yield compared with the continues flooding.