Cambial anatomy and annual rhythm of secondary xylem development in the twigs of Azadirachta indica A. Juss. (Meliaceae) growing in different forests of Gujarat State

摘要

Seasonal behaviour of vascular cambium and development of secondary xylem were studied in the 2- to 3-year-old branches of Azadirachta indica (Meliaceae) growing in moist deciduous (MDF), dry deciduous (DDF) and scrub land (SF) forests of Gujarat State, India. Development of xylem began with the sprouting of new leaves in January in both MDF and DDF. Xylem production culminated in July in MDF whereas it reached peak in April and July in DDF. Cambial cells ceased to divide with the maturation of leaves in November and October in MDF and DDF, respectively. Mature xylem and phloem derivatives surrounded the cambium in December in MDF and November in DDF. Radial growth in the branches of tress growing in SF was found continuous throughout the year with peak cambial activity in April, July and November. In all the three forests, maximal radial growth was encountered in July when the rains were heavy. Cambial activity and xylem development showed significant correlation with the phenology of the treesin MDF and DDF whereas cambium was found active throughout the year and no correlation was found between the cambial activity and phenology in SF.