Abstract
Biomass investment in pods, seeds and seed packaging was studied in Erythrina suberosa Roxb. from the campus of the University of Karachi, Pakistan. The pods were tardily dehiscent or indehiscent for long period of time. The seeds were placed in the pod lengthwise. On an average, the pod was 21.96 ± 0.78 cm long, 2.12 ± 0.43 cm broad and 1.49± 0.29cm thick at the mid of the middle seed chamber. The mean seed was 13.31 ± 0.9mm long, 8.77 ± 0.104 mm broad and 7.78 ± 0.50mm thick. The mean sphericity of seed was 72.11 ± 0.41%. On an average pod weighed 4.140 ± 0.1478g, ranging from 1.475 to 10.5431g (CV: 30.27). The pod weight was distributed asymmetrically; skewed positively and leptokurtic [Kolmogorov-Smirnov z (KS-z) = 1.352; p < 0.052]. The brood size (sensu Uma Shaanker et al., 1998) averaged to 3.62 ± 0.125 per pod varying from 1 to 9 (CV: 37.07%). Brood size distributed asymmetrically with significant degree of positive skewness (PSD) and leptokurtosis. There were two types of seeds E. suberosa produced a) light brown seeds b) dark reddish brown seeds. The seed mass averaged to 2.4594 ± 0.0929 g per pod and varied by a quantum of 40.5%. The distribution of mean single seed weight for a pod (MSSW) was asymmetrical (negatively skewed (NSD) and leptokurtic) among the pods. It averaged to 0.6825 ± 0.0109g and varied from 0.0634 to 0.9324g The pericarp mass per pod varied from 1.3560 to 6.5653g (CV: 56.41%) and averaged to 1.6809 ± 0.0884g. There was no trade-off between fruit size and allocation of resources to seeds. The distribution of pericarp mass showed PSD and leptokurtosis. Some 40.17 ± 1.09 % of the pod biomass was allocated to pericarp (seed protection) and 59.83 ± 1.09 % to the seeds (reproductive function). In a linear model, seed weight per pod (SWPP) coupled with TNS (brood size) as independent variables influenced MSSW significantly (r = 0.754 p < 0.0001). In this model, brood size influenced MSSW negatively. The weight of individual seed for a sample of 412 seeds averaged to 686.49 ± 7.287 mg varying from 51.0 to 987.6 mg (19.36-fold variation). Seed packaging cost (SPC) in E. suberosa was 0.7480 ± 0.4202 g.g-1 .seeds and 0.4959 ± 0.0245 g.seed-1 . The seed packaging cost (SPC2 = g.g-1 .seeds) related with brood size in accordance with a negative power model (exp. = -0.561863) i.e. the investment of biomass in pericarp had a negative trade-off with brood size.
