Durval Dourado Neto

Measurement and simulation of solar radiation availability in relation to the growth of coffee plants in an agroforestry system with rubber trees

Solar radiation is an important factor for plant growth, being its availability to understory crops strongly modified by trees in an Agroforestry System (AFS). Coffee trees (Coffea arabica - cv. Obata IAC 1669-20) were planted at a 3.4 x 0.9 m spacing inside and aside rows of monocrops of 12 year-old rubber trees (Hevea spp.), in Piracicaba-SP, Brazil (22o4230 S, 47o3800 W - altitude: 546m). One-year-old coffee plants exposed to 25; 30; 35; 40; 45; 80; 90; 95 and 100% of the total solar radiation were evaluated according to its biophysical parameters of solar radiation interception and capture. The Goudriaan (1977) adapted by Bernardes et al. (1998) model for radiation attenuation fit well to the measured data. Coffee plants tolerate a decrease in solar radiation availability to 50% without undergoing a reduction on growth and LAI, which was approximately 2m2.m-2 under this condition. Further reductions on the availability of solar radiation caused a reduction in LAI (1.5m2.m-2), thus poor land cover and solar radiation interception, resulting in growth reduction.

Simulação estocástica da radiação fotossinteticamente ativa e da temperatura do ar por diferentes métodos

The purpose of this work was to compare three methods for simulating data of photosynthetically active radiation and air temperature, using daily parameters of 17 stations of Sao Paulo State, Brazil. The simulation of those elements was carried out for de 1 st and the 16 th day of each month, through three cases: nonsymmetric triangular distribution; normal distribution truncated at 1.96 standard deviation; and bivaried normal distribution. The simulated data were evaluated through the tests of homogeneity of variance F and Bartlett, t test, agreement index of Willmott, angular coefficient of the straight line, the index of performance of Camargo and tack the normal distribution (uni-varied). The simulation using the bi-varied normal distribution is most appropriate for representing the climate variables.

Alterações fisiológicas, fenométricas e produtiva na cultura da soja devido ao uso de cinetina

Soybean [Glycine max (L.) Merrill] is the most widely grown oilseed in the world, with 80 % of its production concentrated in the United States, Brazil and Argentina (USDA 2013). In Brazil, the average yield increases around 30 kg ha-1 year-1 and is currently about 3,000 kg ha-1, which is far from the plant’s genetic potential of up to 20,391 kg ha-1 (339.9 bags ha-1) (Navarro Júnior & Costa 2002). The yield potential of the crop is ruled by the genetic characteristics of its seeds. However, ABSTRACT RESUMO