Effect of potassium on TQR-8 paddy variety growth, yield and lodging at high nitrogen application rate

A field experiment was conducted in the net house of School of Sustainable Agriculture in University Malaysia Sabah, Sandakan to study the effect of potassium on TQR-8 paddy variety growth, yield and lodging under high nitrogen application rate. The objectives of the study were to evaluate the effect of potassium application rates on the growth and yield of TQR-8 paddy variety under high nitrogen application rate and to evaluate the effect of potassium application rates in the lodging effect of TQR-8 paddy variety. This study was conducted from June 2013 until November 2013. The experimental design used was completely randomized design (CRD) using potassium fertilizer application rate of 30 kg ha-1 (control), 50 kg ha�¹, 70 kg ha�¹, 90 kg ha�¹, 110 kg ha�¹ and 130 kg ha�¹ with 3 replicates. The results showed that for vegetative growth of paddy plants, treatment 6 (130 kg ha�¹) resulted in the highest plant height which was 118.93 cm and highest culm height of 78.32 cm. Treatment 4 (90 kg ha�¹) had the highest tillers number of 29 tillers, and treatment 3 (70 kg ha�¹) had 94.30 % of percentage of productive tillers. For yield component of paddy plants, treatment 4 (90 kg ha�¹) had 26 panicle numbers, and extrapolated yield of 10.90 tons ha-1�¹, treatment 3 (70 kg ha�¹) had 24.89 g on weight of 1000 grains. Treatment 1 (control) with 30 kg ha�¹ of potassium fertilizer application rate had the highest panicle length of 23.71 cm. Treatment 5 (110 kg ha�¹) had the highest percentage of filled grains of 82.43 % and lowest percentage of empty grains of 17.57 %. For stem strength of paddy plants, the highest diameter of first internodes was treatment 6 (130 kg ha�¹) which was 0.67 cm, highest thickness of first internodes of 0.17 cm of treatment 3 (70 kg ha�¹) and lowest length of first internodes was 1.69 cm of treatment 3 and 6. For second internodes, treatment 6 (130 kg ha�¹) had 0.60 cm of diameter, 0.18 cm of thickness and 4.97 cm of internodes length. Thus, it can be recommended to farmers that the application rate of potassium fertilizer of 90 kg ha-1 because it can produce the highest extrapolated yield of 10.90 tons ha�¹, third lowest length of first internodes (2.19 cm), third lowest length of second internodes (5.34 cm), number of tillers (29 tillers) and number of panicle (26 panides). The second recommendation is 110 kg ha�¹ potassium fertilizer application rate because it can produce the second highest extrapolated yield of 10.77 tons ha�¹, highest percentage of filled grains (82.43 %), lowest percentage of empty grains (17.57 %), second lowest length of first internodes (1.99 cm) and second lowest length of second internodes (5.31 cm)