Abstract
One hundred mature pods from a solitary tree of Acacia stenophylla in the Botany Department of University of Karachi, (tree nearly 15 cm in stem diameter, 7.2 m in height and 17 m2 in canopy area)- were collected in the month of November 2011 and studied for various size parameters. The number of mericarps per pod was highly variable (82.4%) trait and averaged to 6.07 ± 0.24. The brood size averaged to 3.50 ± 0.17seeds. This trait exhibited positively skewed distribution. An average pod weighed to 1.2126 ± 0.4569g (0.1311 to 2.5839g). The frequency of pods containing seed in each mericarp was low (8%). On an average 59.88 ± 2.17 % of the mericarp in a pod had seed. The seed mass per pod varied by a quantum of 51% and averaged to 0.3889 ± 0.0168 g and maximally 0.905g in one pod with no seed yield in 3% of the pods. The pericarp mass of pods varied from 0.1311 to 1.7741g per pod (CV: 40.11%). The weight of single seed for a sample of 945 seeds collected from 100 pods was less variable (20.5%) as compared to the brood size (CV: 47.5%). The weight of individual seed averaged to 139.49 ± 0.939 mg varying from 29.9 to 201.6 mg (6.74 -fold variation). The distribution of seed weight was asymmetrical (negatively skewed). There was a linear relationship between logarithms of seed yield per pod and mass of the pod (r = 0.7753). The slope of the line (b) was 1.036, not significantly different from 1 (t = 0.266, NS). Also, there was significant linear positive relationship between log (number of seeds per pod) and log (pod mass). The slope (b = 0.942) of the regression was not significantly different from 1 (t = 0.495, NS). There was, however, significant seed number-seed weight trade off. The seed packaging costs for 97 pods (excluding three pods yielding no seeds) was expressed on the basis of residual pericarp (g).g-1 seeds (SPC1) and residual pericarp (g) per seed (SPC2). The SPC1 averaged to 2.3732 ± 0.1160 g.g-1 seeds and SPC2 averaged to 0.2495 ± 0.0108 g per seed varying by 48.2 and 42.5%, respectively. On individual seed basis, seed packaging cost was 1.78 times of the average seed weight. SPC1 and SPC2 both distributed asymmetrically (positively skewed) i.e. the magnitude of the SPC was quite high in few pods - generally those yielding single seed. The results are discussed in ecological context.
D. KHAN, ZULFIQAR ALI SAHITO. (2013) VARIATION IN POD- AND SEED-SIZES AND SEED PACKAGING COST IN ACACIA STENOPHYLLA A. CUNN. EX. BENTH. - AN AUSTRALIAN WATTLE GROWING IN KARACHI, PAKISTAN, fuuast Journal of Biology, Volume 3, Issue 1 .
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