(29(2):81-92)期作間水稻不同器官內碳水化合物與氮磷鉀濃度變化比較

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 cuims 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 hea(S)ding) 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 cuims 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 cuims 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. 本試驗在臺北與臺中二地區進行，於水稻生育各重要階段測定不同器官內之非構造性碳水化合物、氮、磷與鉀濃度，並比較期作間之差異，以明瞭臺灣地區二期作水稻低產的生理原因。 水稻之稈與葉鞘，在幼穗分化與發育期間，明顯的累積非構造性碳水化合物（TNC）, 1978 年臺中地區試驗發現，一期作水稻於抽穗前 15 天之 TNC 濃度最高，二期作則於抽穗前 28 天最高不 1976-1977 年臺北地區兩期作均於抽穗時達到最高濃度。期作問之比較顯示，一期作水稻抽穗期稈部貯存之碳水化合物總量遠超過二期作。 水稻葉片部位之氮素濃度較高，但稈與葉鞘之磷、鉀濃度超過葉片。一期作生育初期葉片之氮濃度高於二期作，但至幼穗發育階段，差異已不明顯，二期作甚至有偏高的趨勢。葉片與稈部之鉀濃度方面，則任何生育階段均以一期作為高。水稻於抽穗前貯存之碳水化合物不足，葉片內較低的鉀濃度，以及植株內氮素的組成而非濃度，可能為二期作水稻低產的重要生理原因