Atraso na colheita do milho-pipoca e os efeitos sobre a qualidade de grãos

Abstract

The culture of popcorn (Zea mays L) in Brazil is very significant, so that the country is the second largest producer. The largest domestic production is recorded in Campo Novo dos Parecis, in the state of Mato Grosso, responsible for 70% of national production. However, informations of the quality of the grains in relation to cultivation and harvesting are still scarce. Was evaluated in this work the effect of delays in harvesting on the quality of popcorn grains produced in the harvest 2014/2015 (1st harvest), in the north of Mato Grosso. The planting was held on 11/8/2014, in three different population arrangements, totaling 75,000, 80,000 and 100,000 plants per hectare in each. The cultural practices were carried out according to the recommendation for culture. The grains were harvested at four different times, as follows: 105, 110, 115 and 120 days after sowing. The harvesting, threshing and cleaning were done manually. Analyses were performed in the Postharvest Laboratory UFMT Campus of Sinop. After harvesting, the popcorn was subjected to drying in an oven with forced air circulation at 40 ° C for standardization of the water content to 13%b.u. The quality was evaluated by the following parameters: mass of grain; grain volume; geometric diameter of the grain; sphericity; circularity; thousand grain weight; bulk density; true density; germination; accelerated aging; expansion capacity; detecting fungi associated; and storage over time. The data were submitted to analysis of variance with 5% significance. In relation to delay of the harvest there have been significant results for the variables: grain mass, grain volume, geometric grain diameter; thousand grain weight; bulk density; germination; and capacity for expansion. The results indicated that the grains of popcorn harvested in the 3rd stage (115 days), in general has better quality, with best values for most of the parameters analyzed. The capacity expansion (CE) showed an increase throughout the stages of harvest, which ranged between 105 and 120 days after sowing. All samples showed values above 30 mL g-1 which is the minimum amount required for marketing in Brazil. Fungi were found: Fusarium sp., Aspergillus sp., Penicillium sp. in all samples of grains. Higher crowding between plants showed the highest values of the EC. There was no significant difference between the population arrangements and fungal incidence. During the storage period, the EC decreased.