Cambial Activity and Wood Anatomy in Prosopis Spicigera (Mimosaceae) Affected by Combined air Pollutants

Abstract

Seasonal cambial activity and xylem anatomy were studied in Prosopis spicigera Linn. (Mimosaceae) growing under the influence of combined air pollutants. Cambial cell division and differentiation of secondary xylem began in April, reached a peak in July–August and ceased in October in trees (normal) growing in a relatively unpolluted locality. In contrast, in trees (affected) growing near a fertilizer complex, the initiation of cambial activity was delayed by one month and the cambium ceased to divide in September. Considerable variations were noticed in the structure and arrangement of xylem derivatives between affected and normal trees. The vessel lumen diameter was reduced and vessel frequency was significantly higher in the affected trees. Axial parenchyma was aliform to confluent in normal trees compared to mainly vasicentric parenchyma with heavy accumulation of tannin contents in affected trees. Cambial activity and xylem development did not show any correlation with the phenology of affected trees.