Effect of potassium on growth, yield and lodging of three rice varieties grown on paddy soil

A pot experiment was conducted to evaluate the effect of potassium on growth, yield and lodging of two selected Sabah traditional rice varieties (Padi Wangi and Serendah Merah) and Sri Sabah paddy variety (TR9) as HYV. A 3 x 3 factorial completely randomized design (CRD) with three replications for each treatment combination was used. The treatments for N : P2Os: K2O used were 60:30:30 kg ha-1, 60:30:60 kg ha-1 and 60:30:90 kg ha-1 where three split applications of fertilizers were applied to the rice plants, namely basal application before transplanting, topdressing applications at maximum tillering and panicle initiation stages. The results showed that there is significant interaction effect of potassium application rate and rice varieties on the 1000-grain weight, extrapolated yield per season and internode length of two lowest nodes. The rate of 60 kg ha-1 produced the lowest plant height (114.67 cm), highest 1,000-grain weight (26.23 g) and the highest extrapolated yield per season (5.25 t ha- 1). This application rate also resulted in the lowest culm height (80.11 cm) and highest culm diameter (5.15 mm) that can reduce the lodging susceptibility of rice plants. For the traditional rice varieties, Serendah Merah (V2) produced the highest 1,000-grain weight (26.23 g) and the highest extrapolated yield per season (5.25 t ha-1). This variety also has shorter maturity period of 100-110 days which enables the farmers to cultivate the rice plants for two cycles or even five cycles for every two years. For lodging parameters, Padi Wangi (Vl) resulted in the lowest culm height (77.86 cm) and highest culm diameter (5.55 mm) and the lowest internode length between two lowest nodes (3.50 cm). The Sabah local traditional rice varieties had a potential to be cultivated as the potassium fertilizer application contributed to higher rice yields and some of their lodging characteristics were minimized