Studies on the Allowable Range of Accuracy in Field Seeding Parameters for Daikon-Radish and Chinese Cabbage

Abstract

Farming work with agricultural machinery should be practised according to physical parameters which will not adversely affect the crop yield. The author attempted to determine the allowable range of seeding conditions for machinery cultivation of Daikon-radish and Chinese cabbage. The investigation was conducted for three years from 1972 to 1974. The results obtained are summarized as follows:
1. Germination of Daikon-radish was highly influenced by the size distribution of clods smaller than about 2.0cm in diameter in the soil, and the most satisfactory germination rate was obtained when the soil contained clods of this size at a rate of more than 40% in weight. On the other hand, germination of Chinese cabbage was highly influenced by clods smaller than 1.0cm in diameter, and soil containing clods of this size range at a rate of 25% or more in weight was favorable for germination.
2. The allowable range of depth for seeding was determined as follows: 1-4cm for Daikon-radish and 1-3cm for Chinese cabbage both in clayey loam and in sandy loam, and 2-4cm for Daikon-radish and 1-3cm for Chinese cabbage in sandy soil. The allowable range was defined to be the range of depth which would yield at least 70% germination for the plot in which the highest germination rate was obtained in the test, and which would avoid unfavorable factors to the germination such as susceptibility to damping-off fungus.
3. Root weight of Daikon-radish per plant decreased with increased planting density, but there was no significant difference in yield per unit area among the plots with different planting density. The same trend was observed between head weights of Chinese cabbage and planting density irrespective of maturing periods of the varieties tested, but there was an increase in yield per unit area with increased planting density. These results indicated that the allowable range of planting density should be determined by the prefered root weights rather than yields in Daikonradish and by the prefered head weights and yields in Chinese cabbage.
4. The increase of variation in hill spacing within rows resulted in a decrease of yield both in Daikon-radish and in Chinese cabbage, and an increase of variation both in root weight of Daikon-radish and in head weight of Chinese cabbage. This effect was higher in Daikon-radish than in Chinese cabbage.
5. The root weight of Daikon-radish and head weight of Chinese cabbage increased on a hill adjacent to a vacant hill. The rate of increase was higher in the former case than in the latter. When there were more than two successive vacant hills, the root weight of Daikon-radish on a hill adjacent to them increased slightly but no visible increase was observed for the head weight of Chinese cabbage.
6. The yield per unit area decreased with a rise in the percentage of vacant hills in Daikon-radish and in Chinese cabbage. In case of the same percentage of vacant hills, the smaller the variations in hill spacing were, the smaller the yield reduction was. When the allowable level of yield reduction was no more than 10%, the allowable percentage of vacant hills for Daikon-radish was greater than for Chinese cabbage. The variation of root weight of Daikon-radish or head weight of Chinese cabbage was proportionate to that of the distance between hills due to the existence of vacant hills. The variation in root weight of Daikon-radish was larger than that in the head weight of Chinese cabbage.