THRESHING, SIZE CLASSIFICATION AND STORAGE ON POPCORN SEEDS QUALITY

Abstract

The objective of this research was to evaluate the effect of threshing and classification in size on the physiological quality of popcorn seeds DFT 2 (selection cycle 1), during storage in two different environments. The seeds, with 11% of initial moisture content (wet basis), were submitted to manual or mechanical threshing, using a stationary thresher with cylinder rotation of approximately 250 rpm. After threshing, the seeds were classified in size using sieves with different meshes and the percentage of retention in the sieves and the weight of 100 seeds were obtained. To evaluate the mechanical damage and the physiological quality of the seeds, we’ve tested the following treatments: seeds retained in oblong-holed sieve number 12/64 x 3/4", seeds retained in round-holed sieves number 13, 14 and 15/64" and the control. The seeds were fumigated with fosfine and stored in conventional store (Seed Processing Unit), in Viçosa-MG, for a period of 10 months. The evaluations of seed physiological quality, as well as the determination of the moisture content, were accomplished in the beginning and after 10 months of storage. The mechanical damage was evaluated by the 4% iodine dye test, in the beginning of storage. The results showed that mechanical threshing had harmful effect on germination and vigor of seeds. The seeds without size classification were the most damaged mechanically, followed by round seeds that obtained an intermediate result in relation to flat ones. The popcorn seeds had their vigor reduced when stored under the environmental conditions of the conventional store in Viçosa. The effects of mechanical damage and storage on germination and vigor were not related to seed size.

Keywords

• seeds: popcorn: threshing: seed size: storage