Sistema rodoviário de transporte na qualidade fisiológica de sementes de milho

Abstract

Demand for hybrid maize seed quality is increasing every year, and to meet it seed companies are adopting specific techniques in all phases of production from production fields to seed sowing fields. Among them, especial attention should be paid to forms of transporting seeds, since the effect of temperature and humidity in transportation over long distances may reduce seed vigor and viability significantly. This study aimed at evaluating the influence that both seed transporting in box truck and bulk-tarped truck and the period spent in transportation until the final destination may have over germination and vigor of hybrid corn seeds. This research was carried on partnership basis between Instituto de Ciências Agrárias and Syngenta Seeds Ltd. It encompasses four experiments consisting of combinations of both two types of transportation (in box truck and bulk-tarped truck) and two seed positions on the pallet (upper and lower). Each experiment s treatments were divided into parcels and tests were performed to evaluate seed germination and vigor, besides plant emergence in sand (readings of emergence rates took place at each 12-hour spin). These data allowed calculating the following variables: emergence, emergence rate index, initial time, final time, average time, time variation coefficient, sync, uncertainty, and relative frequency. Each seed position on the pallet had its data compared individually; and conjoint analysis was considered to analyze comparatively the effect resulting from seed position on the pallet and from transport types. Conclusions point out that transportation in bulk-tarped truck may be more harmful to corn seeds quality than in box truck; that seed germination and vigor reduced when seeds transported were placed at the top of pallet in bulk-tarped trucks; periods of time above 96 hours of transportation, especially in bulk-tarped trucks, affects seed quality; seeds germination and vigor are influenced by hybrid type during transportation; small differences in seed germination rates, however significantly, reflect the proximity of these values among replications and, thus, this process s low variability.