The Relation of the Water Content of Loquat Trees to Various Weather in Early Spring

Abstract

Since it is said that evergreen fruit trees, the water absorption of which is very much reduced at low temperature, often suffer more from the dryness of winter wind than from its coldness, the water content of the Tanaka loquat tree was investigated in the cold season. The water content of the leaves was measured with the impedance bridge which had special measuring terminal plates, and that of the trunk was measured with a hundredth millimeter dial guage and indicated in terms of radius fluctuation. The results of the investigation was summarized below.
1. The daily water content of the leaves reached the minimum at 4 p.m. and the maximum at 2 a.m., the range of fluctuation being 2.5 percent. That of the trunk showed much the same change.
2. In the daytime, the water content of the leaves of the outer crown was larger than that of the inner crown and reached the minimum at noon. The water content of the leaves of the inner crown reached the minimum 6 hours later, and so did that of the trunk 2 hours later than that of the leaves of the outer crown. The similar type of fluctuation was observed in the water content of those three.
3. The water content of the leaves was largest on rainy day and smallest on windy day, the difference being about 4 percent at the largest. The water content of the leaves on fine day was about 1 percent larger than on windy day. It may be said that the loquat leaves have so numerous hairs that they can keep transpiration down a little. It may be for this reason that the water in the leaves did not show great change in amount. It is suggested, therefore, that the loquat trees do not suffer very much from dry winter wind in warm regions.