A simple method to monitor onion bulb dormancy.
Bufler, G.
ISHS Acta Horticulturae 553: 129-130.
2001
บทคัดย่อ
A method was developed to monitor onion bulb dormancy. Sprout leaves were isolated from a subset of 40 bulbs of a short-storing onion cultivar, Stuttgarter Riesen (grown from sets), randomly selected from the stored bulk sample. Two leaf-sheath lengths (1.6-2.5 mm and 2.6-3.5 mm), representing 2 classes of bulbs, were monitored. To detect initial sprouting the one-tailed confidence limit of the mean leaf-blade length of a typical dormant bulb stage was calculated and compared with the leaf-blade lengths of individual bulbs. A typical dormant bulb stage was assumed to be represented by bulbs at the time of foliage lodging in the field, i.e. at regular harvest. A similar experiment was carried out with a long-storing onion cultivar, Copra F1 (directly sown), except that the monitoring covered sprout leaves of 20 bulbs at each sampling date, and only the 2.6-3.5-mm leaf-sheath length group. The one-tailed confidence limits of the mean leaf-blade length of Stuttgarter Riesen determined at harvest were 4.7 and 4.9 mm, respectively, in the 1.6-2.5-mm and 2.6-3.5-mm leaf-sheath length groups. Bulbs with leaf-blade lengths exceeding these confidence limits were denoted as 'sprouting'. During storage the percentage of sprouting bulbs increased similarly in both leaf-sheath-length groups. Sprouting of Stuttgarter Riesen began immediately after harvest, whereas sprouting of Copra F1 was detectable 5 weeks after harvest. By applying the method, the contributions of both dormancy and rate of sprout growth to storability and the effects of preharvest and postharvest factors on the dormancy of onion bulbs can be evaluated.