Physiological quality of Sideroxylon obtusifolium (Roem. & Schult.) Penn. seeds classified by size

Abstract

Sideroxylon obtusifolium (Roem. & Schult.) Penn. (quixabeira) is a sapotacean tree native to the Brazilian biome Caatinga. The species seeds have different sizes, and a dormancy imposed by the water-impermeable seed coat. In order to improve the physiological quality of the lot, seeds were sorted by size through sieves with the following circular diameters: 3.60, 4.00, 4.75, and 6.35 mm; and mixture (without seed separation). Experimental design was completely randomized, with five treatments and four replicates of 25 seeds, each. Seeds were previously scarified and tested for germination and emergence. The following variables were analyzed: percentage and speed index of both germination and emergence, seedling length and seedling dry matter. Counting of normal seedlings was carried out on alternate days. Size-based classification improves the quality of quixabeira seed lots; for the propagation of quixabeira, we suggest the use of large seeds (6.35mm), since size variation influences both germination and vigor; smaller quixabeira seeds have low physiological quality and should be discarded from the lot; seed selection and classification is a technique that should be recommended for the evaluation of physiological quality of quixabeira seeds.