Journal of Taiwan Agricultural Research

Author:Lit-Fu Chan, Chun-Tang Lu, Meng-Li Wei and Hsiu-Ying Lu

Abstract:

    The purpose of this study was to investigate the effect of planting seasons on the pattern of dry matter and N accumulation for wetland taro. Field experiments were conducted in the January, May and September crops of 1995-1996. The amount and rate of dry matter and N accumulated were measured in different plant fractions during the whole growth periods. The accumulation of dry matter and N were strongly modified by planting seasons and plant age. Dry matter and N accumulated in the top (leaf and petiole) at the vigorous top-growth stage during the 3-5 months after planting was the determinant of biomass production of wetland taro. As a result of higher temperature and solar radiation at the vigorous top-growth stage, dry matter and N were substantially accumulated more rapid in the January crop. This resulted in greater source efficiency and rapid corm hulking, in favor of the yield at the maturity stage. When planting taro in September, low temperature and low solar radiation at the vigorous top-growth stage decreased the rate and amount of dry matter and N accumulation, moreover, dry matter and N accumulated in the top still increased at the corm rapid-bullring stage. This resulted in poor yield at the maturity stage. The May and January crops had similar pattern in the accumulation of dry matter and N, but the accumulation rate in May crop was slower than that in January crop. The relative ratio of accumulation rates between N and dry matter in the top at the vigorous top-growth stage remained the same among the different planting seasons. Planting seasons and plant age showed no significant effect on the partition ratio of dry matter and N accumulated by different above-ground organs. The results showed that about 1/3 of the plant dry matter in the top was distributed to leaves, and 2/3 to the petioles. For the total N content in the top, about 6/10 was accumulated in the leaf, and 4/10 in the petiole.

Key words:Taro, Planting seasons, Dry matter accumulation, Nitrogen accumulation, Vigorous top-growth stage

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