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Cuiabá, Brazil

de e Albuquerque M.C.F.,DFF UFMT | Caneppele M.A.B.,DFF UFMT | Brito J.,IF UFMT | Costa J.,Graduando de Agronomia UFMT
Revista Brasileira de Engenharia Agricola e Ambiental

The objective of this study was to develop a method to determine corn grain resistance to mechanical damage. Seven hybrids were evaluated: AS1535, AS1570, AS1575, AS3430, AG7000, P30F80, and DKB390. The impact imposed to the grain consisted of different weights (50, 100, 150, and 200 g) and heights (7, 17 and 23 cm), applied on two kernel regions, dorsal and ventral surface; the grain was then submitted to the iodine and damage severity tests. A completely randomized experimental design was adopted, in a 7 × 3 × 2 factorial scheme represented by seven hybrids, three weights and two regions: four sub samples of 25 grains were used in each treatment. The results allowed the hybrids to be separated into three levels of resistance: susceptible (AS1535, AS1570, and AS1575), intermediately resistant (AG7000 and P30F80), and resistant to mechanical damage (AS3430 and DKB390). The region most susceptible to the impacts was the ventral surface, where embryo is located. The proposed method was effective to produce differential mechanical damage indices between susceptibility and resistance standards. Source

Pinto Jr. O.B.,IF UFMT | Vourlitis G.L.,California State University, San Marcos | Sanches L.,UFMT | Dalmagro H.J.,IF UFMT | And 2 more authors.
Revista Brasileira de Engenharia Agricola e Ambiental

The objective of this study was to analyse the behavior of sap flow in a transition Amazon-Savannah forest species, to characterize the dependence of sap flow as a function of atmospheric vapor pressure deficit (VPD). The sap flow was measured using the technique proposed by Granier, using heat dissipation probes in five different species. The data were divided into four seasons. In the experimental period, the curves of seasonal variation of sap flow showed an occurrence of peaks in the wet season. This seasonal sap flow trend was evidenced by the relationship between daily values of transpiration and VPD. The threshold value of VPD at these stations ranged from 1 to 1.5 kPa. Considering sap flow as representative of plant transpiration, reduction of the flux in the dry season did not confirm the hypothesis of maintenance of evapotranspiration process. The sap flow in the studied species was influenced more by weather than soil water availability. This raises the possibility of water storage in the stem during drier periods, when leaf area decreases. However the transpiration rate is not significantly different from that of the rainy season. Source

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