加温時期の異なるブドウ‘マスカット•オブ•アレキサンドリア’の根の生長及びその活性に及ぼす地温の影響

Abstract

Investigations were carried out to clarify the effect of root temperature on budbreak, growth of shoots, flower clusters, and roots in 4-year-old potted‘Muscat of Alexandria’vines grafted on‘Hybrid Franc’rootstock. Root temperature was controlled to 13, 20, 27, and 34°C from December, and to 13 and 27°C from February under forced conditions. Root activity was determined in terms of TTC reduction and O2 consumption. Seasonal changes in activity in unheated vines were also determined for comparison.1. In the vines heated from both December and February, higher root temperatures resulted in fewer days being required for budbreak, especially when forced from December. The percentage of budbreak was also higher in the vines at 27°C than at 13°C. Shoot growth was vigorous at 27°C. When forced from December, the development of flower clusters was more vigorous at 27°C than at 13°C, but there was little difference between the two temperatures from February.2. There was marked promotion of rooting at 27°C with forcing from both December and February, and it was more marked in the forcing from February than from December at both 13 and 27°C. The same trend was observed in root elongation. At 34°C the new roots were small in diameter and short in length, while they were thick at 13°C and were of medium size in the plots at 20 and 27°C. The development of the stele in new roots at 27°C was superior to that at 13°C.3. In the unheated vines, root activity estimated from TTC reduction and O2 consumption was low from December to March, and then it increased gradually towards bursting and then markedly to flowering. In the vines forced from both December and February, the increase of root activity towards bursting after the start of treatments was larger at 27°C than at 13°C, especially in the forcing from February. At both root temperatures the increase was larger in vines forced from February than in those forced from December. Regardless of the time of forcing, root activity was always higher in vines controlled at 27°C than at 13°C throughout the period of the experiment.