Carbohydrate, N, P and K Status of Developing Rice (Oryza saliva L.) Plants Grown in the First and Second Crop Seasons in Taiwan

Abstract

Concentrations of total nonstructural carbohydrates, N, P and K in different plant parts of rice were analyzed at stages of plant development. Differences between crop seasons were also studied to investigate the physiological causes of low yield of the second crop rice. Accumulation of total nonstructural carbohydrates (TNC) in culms and leaf sheaths was most evident during the period of panicle development. Highest TNC concentration was recorded earlier in the second crop (25 days before heading) than in the first crop (18 days before heading) for rices grown in Taichung. It occurred at heading stage in both crops in Taipei area. The first crop rice accumulated significantly higher amount of TNC in culms at panicle emergence than the second crop rice. Concentration of N was higher in leaf blades whereas those of P and K were higher in culms and leaf sheaths. Nitrogen concentration in plant tissues was higher in the first crop during the vegetative growth stage but the difference between crops was less significant as rices grew toward heading. Leaf blades of the second crop rice were considerably lower in K concentration than those of the first crop rice throughout the whole developmental period. Less TNC stored in culms and leaf sheaths before heading, lower K concentration in leaf blades, and the composition, rather than concentration, of N were suggested as possible physiological causes affecting yield potential of the second crop rice in Taiwan.