Christian Viterbo Maximiano

Hydroconditioning has been tested in some crops as an attempt to improve seed performance in the field. Minimum germination standards for corn (Zea mays L.) seeds in Brazil varies from 85% for common, 70% for popcorn and sweet and 60% for super sweet one, due to genotypic effect on physiological seed quality. This study aimed to evaluate the effects of periods of hydroconditioning (0, 30, 60, 90 and 120 minutes) and gas insufflation techniques (atmospheric air, concentrated oxygen and none) on seed germination and vigor of corn seeds of different physiological qualities (high and low) and types (common, popcorn, sweet and super sweet). The experiment was carried out in a 5x3x2 factorial design for each corn type, with four replicates. The evaluated parameters comprised water content, germination and electrical conductivity of seeds; main root and seedling length and dry mass of seedlings. Positive effects of the hydroconditioning were observed on seed reinvigoration of corn of all qualities and types and the best results were achieved with hydroconditioning with air or oxygen insufflation, during 60 to 90 minutes, which is therefore recommended to reinvigorate seeds of common, popcorn, sweet and super sweet corn.

Sweet corn is a vegetable that belongs to the special corn category. It is used exclusively in human food and differs from common green corn because it contains higher sugar content and lower starch content in its grains. The low availability of cultivars with desirable agronomic characteristics has been an obstacle to the expansion of the crop production in the country. Sweet corn seeds have germination problems and low vigor, which makes it difficult to establish the culture in the field. Hydropriming is a technique of physiological conditioning of seeds that consists of soaking seeds in water for certain periods of time, being a low-cost treatment that has shown to be very promising in the invigoration of low vigor seeds. The present work aimed to evaluate the effects of hydropriming in different aeration treatments and soaking periods on the physiological quality of crystal sweet corn seeds. The parameters of germination, seedling and radicle length, seedling dry matter and electrical conductivity were evaluated in view of the effects of aeration treatments by atmospheric air, concentrated oxygen, without aeration at different imbibition periods of 30, 60, 90 and 120 minutes, as well as the interactions between these treatments. According to the results obtained, the hydropriming treatment interacting with the atmospheric air aeration treatment provided an invigoration of the physiological quality of crystal sweet corn seeds.

The technique of controlled hydration of seeds has been used as a method of physiological conditioning to improve their performance in the field. Solution aeration with ozone gas is a promising option in controlling phytopathogens. The objective of the present study was to evaluate the physiological and sanitary quality of maize seeds preconditioned in ozonated water. In the evaluation of the physiological and sanitary quality, maize seeds were submitted to four concentrations of ozone gas (0, 10, 20 and 30 mg L^-1) for five soaking periods (0, 30, 60, 90 and 120 min), with four replicates. Preconditioning maize seeds in ozonated water, followed by natural drying, resulted in a more pronounced initial development of seedlings, measured by means of the emergence speed index, seedling dry matter, seedling length and radicle length, compared with untreated seeds. The initial development of maize seedlings was intensified by the exposure of seeds to water, especially at 0 and 30 mg L^-1 ozone concentrations during the period from 60 to 90 min. Preconditioning maize seeds in ozonated water did not affect the control of Fusarium sp. The fungicide Carbendazim + Thiram resulted in 100% control of Fusarium sp. in the seeds.