Annual Variation of the Growth and its Relation with Meteorological Factors in Potato Plants : I. The aspect of annual variation in shoot fresh weight during the growth and its relations with solar radiation, temperature and precipitation

[摘要] Considering annual variation of the potato shoot growth and its relation with the meteorological factors, fresh weight of shoot (shoot weight) in three main cultivars was weighed at four to six times during the growing season (June to September) through ten years (1972-1981) at the Hokkaido National Agricultural Experiment Station. 1. Annual variation of shoot weight in each variety increased after sprouting to late July, then decreased slightly on August, when the early variety (Danshakuimo) reached the harvesting stage. Thereafter, in two late varieties (Norin No. 1 and Benimaru). it turned to increase again and showed the maximum value on late September (Fig. 1). Comparing it among the varieties, Danshakuimo showed the larger value than the other two varieties since middle July (Fig. 1). Shoot weight, however, showed significant positive relations among the varieties at most of the sampling date. It indicated that, when shoot weight was larger in one variety, it tended to be larger in the other two varieties (Table 2). 2. Annual variation of the date of sprouting influenced little on shoot weight of July 1 (just before the first flowering stage), which depended mostly on the growth rate of shoot weight (shoot GR) from sprouting to July 1 (Tables 1, 3). Shoot GR from July 1 to 15 showed large effect on shoot weight from middle July to late August. Annual variation of shoot weight on late September was, however, mainly affected by the rate of shoot senescence since late August (Fig. 2, Table 3). 3. Shoot GR from sprouting to July 1 was larger when maximum and minimum temperature was higher. The simple correlation coefficients of shoot GR with these factors were, however, realtively low. It seemed also to be effected by solar radiation and precipitation (Figs. 3, 4). In addition, shoot GR from July 1 to 15 showed remarkable relation with maximum temperature in three varieties, i.e. it was smaller when maximum temperature was within 22°-23°C and precipitation was less than 0.5 mm/day (Fig. 5). 4. The relations of solar radiation with shoot GR on July and with shoot weight on August, and of solar radiation with shoot weight of September were significantly negative. The results indicated that potato plants increased the shoot growth and retarded the shoot senescence when solar radiation was limited, which would result in minimizing the decrease of solar radiation interception by the shoot (Figs. 5, 6, 7).

[学科分类] 农业科学（综合）