AXIAL DIMENSIONS OF SEEDS, WITHIN-REGMA ALLOCATION OF PHYTOMASS AND SEED PACKAGING COST IN A WILD CASTOR BEAN, RICINUS COMMUNIS L. (EUPHORBIACEAE)

The axial dimensions of seeds, within-fruit allocation of biomass and seed packaging cost were determined in a wild castor bean plant from village Khuhra, Tehsil gambit, district Khairpur Mirs, Sindh. The dry fruit (regma) weight averaged to 1.6643 ± 0.0215g and varied by 18.53% (0.9493–2.4466g). The castor fruit produced 2 to 4 seeds but generally 3 seeds per regma in 91% of the cases. Eight percent of the fruits had 2 seeds and only 1% produced 4 seeds. The length, breadth and thickness of seeds averaged to 13.85 ± 0.15, 8.45 ± 0.069 and 5.63 ± 0.062 mm, respectively with as low variation as 6.89, 5.13 and 6.92%, respectively. The lowest variation was seen in sphericity (3.91%). The sphericity averaged to 62.78%. Seed weight per regma (SWPR) averaged to 0.9751 ± 0.0137g varying from 0.3466 to 1.3888g (CV: 19.90%). Mean single seed weight in a regma (MSSW) varied by 17.08% among the fruits and averaged to 0.3327 ± 0.0040g (0.1490–0.4629g). It deviated marginally from normal distribution (negatively skewed; KS-z = 1.297, p<0.069). Mean single seed weight (MSSW) related with the magnitude of variation (CV) in seed weights among the seeds of a regma in an inverse fashion. The variation amongst the seed weight (CV) in fruit was largely the direct function of the weight of the smallest seed in the fruits (r = 0.930; F = 1268.16 (p<0.0001) and not the heaviest seed of the regma (r = 0.024, NS). It was observed that MSSW when two seeds developed in a regma was not significantly different from the regular state of three seeds in regma (F = 0.556, p<0.457 and t = 1.873, p<0.10, NS). The very occurrence of four seeds in only two fruits (1%) of the regma didn’t allow the comparison of MSSW of 4-seeded state to 3-seeded or 2-seeded state. These results led us to conclude that there was no competition among seeds developing in the same fruit. Excluding seeds of small category (≤ 100 mg), the individual seed for a sample of N = 552, averaged to 349.307 ± 1.854 mg and distributed normally (KS-z: 1.224, p<0.100). It varied only by 12.47% - nearly half to the variation in case of all sizes of seeds inclusive (24.63%). Seed packaging cost per seed (SPC1) and per g. seeds (SPC2) averaged to 0.2297 ± 0.0038 and 0.7029 ± 0.0127g, respectively and varied by a quantum of 23.41 and 14.14%, respectively. There was no trade-off between fruit size and allocation of resources to seeds.