Content area
Full Text
Abstract
The pods and seeds collected from two mature trees of Vachellia nilotica (L.) P.J. Hurter & Mabb. from Karachi were studied for their quantitative characteristics such as their sizes, variation in their weights, inter-seed distances, pericarp and seed yields per pod, brood size and mean single seed weight per pod, pattern of within-pod seed size distribution, mother tree - and pod-related variation of individual seed weight, seed packaging cost and seed number - seed size trade off. The results have been discussed in the context of available ecological literature.
Introduction
Angiospermic fruits typically consist of pericarp and seed (s), which collectively function to maximize plant reproductive success. Seeds are responsible for plant population regeneration in the form of seedling emergence on germination whereas the pericarp provides seed protection and aids in dispersal at times (Primack, 1987; Leishman et al., 2010). The pericarp not only occupies a significant proportion of fruit biomass (e.g., Wil lson et al., 1990), it also determines the immediate physical and chemical environment of the seeds (Primack, 1987). Determining within-fruit reproductive allocation is, therefore, of importance to the understanding of seed size evolution and plant life history strategies (Chen et al., 2010). Within-fruit reproductive allocation has been scarcely examined across a wide range of fruit types and taxa although it is critical to the understanding of the evolution of fruit size and seed size (Chen et al., 2011). Identifying reproductive allocation patterns is one of the major tasks in population biology of plants (Harper, 1977). Several studies have quantified reproductive allocation at both the fruit and seed levels (Obeso, 2004; Lord and Westoby, 2006; Martinez et al., 2007). Fruit size has been frequently suggested to be related to within-fruit biomass allocation between seeds and pericarp (e.g., Herrera, 1987; Willson et al., 1990; Lee et al., 1991; Mehlman, 1993; Celis-Diez et al., 2004; Martinez et al., 2007) and pattern of seed packaging costs may significantly vary among broadly ecological similar species and within species (Willson et al., 1990; Chen et al., 2010; Khan and Zaki, 2012).
Vachellia nilotica (L.) P.J. Hurter & Mabb. is an important tropical tree species of arid regions. It is exceedingly variable species (Ali (1973). Since within-fruit reproductive allocation in our local flora has not yet...