豌豆產量生理研究IV.莢果充實期間氮素與非構造性碳水化合物含量之變化

Studies on the Yield Physiology of Garden Pea (Pisum sativum L.) IV. Status of Nitrogen and Total Nonstructural Carbohydrates of the Developing Pods

採用豌豆嫩莢用品種臺中11號與臺中12號、甜脆型品種新珍及豆仁用品種青仁為材料，於民國77年秋作進行田間試驗。以植株基部算起第20-23節之4個節位為對象，在始花時標示同日開花之花朵，定期取樣，分析莢果充實期間之氮素及非構造性碳水化合物（TNC）累積與分配性狀，至始花後第37日為止，特別著重莢果充實過程中的供源與積儲關係研究，藉以瞭解豌豆之產量生理表現。莢壁氮素濃度與含量皆自發育初期下降，其再轉移性氮素可提供種子充實所需氮素之12%，發生時間則以充實後期較為重要。種子氮素濃度在發育初期顯著下降，顯示在進入快速充實期以前，累積氮素之相對速率較累積TNC之速率為高。莢壁TNC含量不高，對種子充實不具重要性。種子在進入快速充實期以後，TNC／N比值維持穩定，表示具有相近的相對氮素與碳素累積速率，亦即蛋白質與澱粉合成速率尚能相互配合。臺中11號與12號的TNC／N比值遠高於青仁品種，顯示後者種子充實對氮素的需求量超過前者，較不易維持植株的氮素供需平衡，產量潛能亦可能因而較低。

Pea cultivars Taichung 11, Taichung 12, Sugar Snap and Dark Skinned Perfection, representing three different types of the crop, were grown in the fall crop of 1988. Flowers at the 20th to 23rd nodes from plant base were tagged at the day of blooming. Concentrations of total nitrogen (N) and total nonstructural carbohydrates(TNC) in different pod fractions were analyzed at intervals during the period of pod-filling. Both the concentration and amount of N in the pod wall decreased from early pod development. The redistributed N from pod wall contributed to about 12% of seed N, which occurred mainly in the later stage of pod-filling. The high seed N concentration during early pod development indicated that the relative rate of N accumulation by the seed was higher than that of TNC accumulation. The amount of TNC in the pod wall was low and was not considered as a major source of seed carbohydrate. The TNC/N ratio in the seed remained fairly constant during rapid seed-filling, suggesting that the relative assimilation rate of starch and protein were comparable during this period. The high TNC/N ratio in the seed of Dark Skinned Perfection indicated that the balance between N supply and demand of this cultivar was restricted by the high N requirement of seed development. This was proposed as one of the physiological factors causing the low yield potential of Dark Skinned Perfection under condition of the current experiment.