ABSTRACT. This experiment was carried out in order to evaluate the effect of Sitophilus zeamais on physical, physiological and sanitary quality of stored corn. Samples of 500 g of the hybrid OC-705, in three replicates, were conditioned in glasses covered with a screened lid, and kept in chamber at 25±2ºC, 70±5% RH and 12 h of photophase, for 150 days. The infestation levels were 0, 5, 15 and 50 adults/replicate, for the storage periods of 30, 60, 90, 120 and 150 days. The moisture content, classification, weight loss, germination and internal infestation were evaluated monthly. Significant inverse correlations were verified between the number of insects and both the germination and the weight loss; also between the internal infestation and the germination and the standard type. The presence of S. zeamais showed a positive correlation with the weight loss, what means that the internal and external infestations contribute to the reduction of physiological and physical quality of corn seeds. The mean dry matter loss was 0,36%/day, corresponding to a consumption of 0,0001%/insect/month. As the result of those damages, the product suffered reduction of the commercial grade in 30 days, with significant loss in all quality factors.
The experiment was conducted at the Experimental Farm of the Federal University of Mato Grosso in the municipality of Santo Antônio do Leverger, State of Mato Grosso, Brazil to evaluate the agronomic characteristics of corn hybrids in the cultivation of second crop for silage production. The experimental design was carried out with randomized blocks with 23 treatments (hybrids) and three replications. Corn hybrids from different seed companies and recommended for the midwestern region of Brazil, were used. The agronomic traits were: stem diameter (cm), plant height and ear insertion (m); yield of green matter (ton. ha-1), percentage of spike, stem and leaves in green mass; ear productivity (ton. ha-1), dry matter content of stem + leaf and whole plant. Hybrids BF 9304, DKB 370, 177 DKB, BF 9534, BF 9417, AG 5020, BE 9701, P 3021 and P 30F98 had the highest production of green matter, plant height and spike insertion. The hybrid BF 9304 was also prominent for spike percentage (50.55%).
Estimates for the 2018/2019 grain crop indicate production in the order of 238.5 million tons, an increase of 4.7% compared to the 2017/2018 harvest. This production, although satisfactory, could still be greater, were it not for the problems faced with the logistics of grain disposal where billions are lost due to the limited investment in infrastructure. The objective of this work is to establish a percentage loss index, as well as to assess these quantitative losses during bulk grain transportation of corn. The research was developed through a partnership between the National Supply Company (CONAB) and the NTA (Nucleus of Storage Technology), at the Federal University of Mato Grosso. It was established the evaluation of losses related to grain transportation in the main waterways, being bulk corn in BR 163/364 in the State of Mato Grosso. After the choice of the highways evaluated, we carried out research on the data of romaneios in the transportation of corn in bulk. The obtained data, through the romaneios, provided weight of origin, weight of destination, place of origin and place of destination, in this way, by difference was obtained the quantity of grains lost in the transport and the mileage traveled in each route. By means of these data it was possible to obtain three indices of losses, one in Kg/Km (kilogram per kilometer wheeled), another one in Kg/t (kilograms per tons transported), and also determined an index of loss in percentage of grains transported. With the indication of the indices it was possible to evaluate the losses. The Bitrem truck (7 axles) was used as the basis for calculating the losses, since during the interviews this was the type that had the most occurrences in BRs evaluated, with 39%. Based on the questionnaire, the load weight of 38,000 kg was therefore adopted. For the study of corn grain losses in road transport, 39,642 data were analyzed for routs, with 24,902,808.50 km rotated, mean of 628,19 km away by route. The amount of corn grain transported was 1,852,437,042 kg. The total losses were 1,808,951 kg, averaging 45.63 kg of loss per trip. The loss per km was on average of 0.072 kg. Transport of corn grains between Nova Ubiratã and Rondonópolis presented the highest frequency of trips (8629 trips), however the losses were 37,710 kg of grains or approximately 628 bags of corn (60 Kg). The index of percentage loss for maize (0.1025%). This percentage is lower than the adopted one that is of 0.25%, nevertheless, represent considerable losses for the economy. Based on the data obtained in the present study, it can be stated that it is possible to adopt percentage loss rates of less than 0.25% in contracts. It is recommended to adopt the percentage rates of grain loss in road transport of 0.10% for maize.
Sitophilus species are major pests of stored grain and their control is achieved mainly with the use of chemical insecticides, but the indiscriminate use of these products is resulting in several undesirable factors to man and to the environment. Thus, the use of natural insecticides comes as an option to control the insects, while lessening risks to the environment. The study was conducted at the Institute of Agricultural Sciences and Technologies, Rondonópolis campus of the Federal University of Mato Grosso, in the period from March to September 2012. The experiment was conducted under three different storing conditions. Aqueous extracts were obtained by the addition of Allium sativum L, Azadirachta indica A. Juss. and Cymbopogon winterianum Jowitt vegetable powders in distilled water, at a ratio of 5 g per 100 ml, and the levels of chemical insecticides were of 0.04 and 0.15 ml/100 ml of water for deltamethrin and chlorpyrifos, respectively. Treatments were added to the corn grains, which were placed in a 2.5 L glass container, mixed by manual shaking and infested with 20 adults of unsexed Sitophilus zeamais. Grains were stored for 60 days. At 30 and 60 days, the following items were analyzed: bugs count, water content in grains and electrical conductivity. The data were submitted to analysis of variance, and means were compared by Tukey test at 5% probability. At 30 days, the efficiency of chemical insecticides in the control of Sitophilus zeamais was observed in the three storage environments. Vegetal extracts were not effective in controlling insects. The larger number of insects increased the electrical conductivity and humidity values in the grains.
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