Enhancing Productivity and Antioxidant Activities in Thai Colored Rice Cultivars ‵RD69′ and ‵Hawm Gulahb Deang′ Using Chitin-Based Material and Rice Husk

Rice is the major crop of Thailand. However, the rice yield is still limited, especially in local cultivars. Fermented chitin (FC) application to soil has been demonstrated to improve rice growth and yield. The application of biostimulants has been proposed to improve both the yield and quality of ‛RD69’ and ‛HGD’ rice varieties. While FC has been suggested as a potential solution, the specific effects of FC on seed quality and quantity remain insufficiently explored. In this study, pot experiments were conducted to determine the effects of FC and FC with rice husk (FC+RH) treatments on the grain quantity and quality of two rice cultivars, ‛RD69’ and ’Hawm Gulahb Deang’ (HGD), which are colored rice varieties with high antioxidant levels. ‛RD69’ has low apparent amylose content (AAC) and a high percentage of rapidly available glucose (RAG), while ‛HGD’ is the local Thai rice with medium AAC and low %RAG. FC and FC+RH were applied as soil supplements at concentrations of 0.01%, 0.1%, and 0.2% (w/w). The supplementation of 0.2% FC+RH resulted in the highest yield of ‛RD69’ (73%) and ‛HGD’ (30%). Although both FC and FC+RH did not significantly affect the AAC content of both cultivars, FC+RH decreased their %RAG. Interestingly, although FC+RH enhanced the antioxidant activity of the seeds of both cultivars, ‛RD69’ was more responsive to the effects of FC and FC+RH treatments than ‘HGD’, as significantly higher antioxidant levels were detected in ‛RD69’ seeds. These findings suggest that FC+RH supplementation can enhance the yield and quality of colored rice.