Leaf Macronutrient Resorption During Senescence in Three Non-Indigenous Tree Species in Sudano-Sahelian Region of Nigeria

Abstract

This study is aimed at assessing the extent of leaf nutrient resorption efficiency during senescence of three species (Khaya. senegalensis, Syzygium cumini and Pongomia glabra) in the Sudano-sahelian region of Nigeria. The species were selected from grooves of trees found within Maiduguri metropolis. Three leaf samples at different developmental stages (young, matured and senescence leaves) each were collected from the selected species. Each sample was then analysed for nutrient contents. C content ranged from 39.79% in K. senegalensis, 43.89% in S. cumini to 41.59% in P. glabra. Matured leaves of S. cumini have the highest K content with mean value of 9.08mg/kg, whereas young leaves of K. senegalensis and P. glasbra were the highest with mean values of 8.68mg/kg and 8.45mg/kg respectively. There was a significant decrease in K. content during senescence in S. cumini. Senescent leaves of K. senegalensis and P. glasbra have higher Ca content with 1.06mg/kg and 0.81mg/kg, respectively while matured leaves of S. cumini have the highest mean Ca content (0.82mg/kg). Young leaves have the highest mean values of S content in all the leaves of the three species. S declines significantly from matured to senescent in K. senegalensis. Young leaves of S. cumini and P. glabra, and senescent leaves of K. senegalensis have the highest mean values of Mg with 0.29mg/kg, 0.39mg/kg and 0.31mg/kg, respectively. Leaf P content is highest in matured leaves of K. senegalensis, S. cumini and P. glabra with mean values of 0.06mg/kg, 0.04mg/kg and 0.06mg/kg respectively and decreases during senescent. However, the decrease was only significant in P. glabra. The highest mean value for N is recorded in the young leaves of K. senegalensis with 0.04mg/kg, but it is highest in senescent leaves of S. cumini with 0.06mg/kg and P. glabra with 0.17mg/kg