Effect of seed-corm age and weight on the efficiency of corm tuberization in konjak plants (Amorphophallus konjac K. Koch).

Abstract

The efficiency in tuberization of corm and cormlet, and the accumulation of dry matter to underground parts, were investigated using seed-corms from 1st, 2nd or 3rd years which are used as the seed-corms in the cultivation of konjak plants. Results obtained are as follows : 1. The weight of whole plant or corm plus cormlet was high under large seed-corm and the partition of dry matter to underground organ (corm plus cormlet) was no discernible variation between the age and weight of seed-corms. The percentage of dry weight in each organ to total dry weight of corms obtained from the 1st year crop became slightly smaller values than those obtained from the 2nd and 3rd years, and there was an inverse relationship among cormlets weight. As for the shoot dry weight, the percentage of leaflets decreased with increasing the age or weight of seed-corms, but non-photosynthetic organs increased (Figs. 1 and 2). 2. As to the corm tuberization based on fresh weight, there was a close positive correlation between seed-corm weight and leaf area. Further, seed-corm weight negatively correlated with the ratio of leaf area/seed-corm weight. The ratio of corm or corm plus cormlet weight per seed-corm weight increased with ageing of seed-corms. However, the negative correlation was found between leaf area/seed-corm weight and corm weight/leaf area ratio (Fig. 1). 3. The corm tuberization based on dry weight was similar to that based on fresh weight. However, there was a large difference between the percentage of dry matter and the age of seed-corms. The difference in leaf area/seed-corm weight ratios among the age of seed-corms was smaller than fresh weight base. Corm/seed-corm weight ratio slightly increased with increasing the age of seed-corm, however, cormlet/seed-corm weight ratio decreased. Corm plus cormlet/seed-corm weight ratio was high under small or young seed-corms (Table 1 and Fig. 4). 4. The ratios of corm, corm plus cormlet, and whole plant weight/leaf area increased with the ageing of seed-corms and specific leaf weight, soluble protein and chrollophyll contents also increased. These values were much higher in the crops in 3rd years than in 1st years. It was suggested that there was a close relationship between photosynthetic rate and age of seed-corm in konjak plant (Fig. 5 and Table 3).