Viability of irrigation by porous capsule method in arid and semi-arid regions.

This paper presents the results of four field experiments carried out with the objetive of evaluating the feaibility of irrigation by porous capsule method, from 1979 to 1983, at Bebedouro Experiment Station, EMBRAPA-CPATSA, Petrolina, PE, Brazil. The irrigation system consisted of fulcrum of cone shaped porous capsules, interconnected with conduit pipe and installed in the soil at equidistance and 0.10 m deep along contour lines. The hydrostatic pressures studies did not significantly influence the crop yield, but influenced, at 0.10 level, the daily water release from porous unit. The mean yields for watermelon (Citrullus vulgaris Shard), var. Charleston Gray, for muskmelon (Cucumis melo L.) var. Valenciano Amarelo, and for maize (Zea mays L.), var. Centralmex, estimated in ton/2,500 units/ha or in cobs/2,500 units/ha, were 28.5, 10 and 17,500, respectively. The water consumption for watermelon, musk melon and maize was, respectively, 60 mm, 60 mm and 100 mm in a deep sandy yellow-red latosol. The cost of the system was US$ 1.677,41/ha.

Comparison of biology between Helicoverpa zea and Helicoverpa armigera (Lepidoptera: Noctuidae) reared on artificial diets.

The objective of this study was to compare growth and development of Helicoverpa zea Boddie and Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) larvae that were feeding on an artificial diet. Neonate larvae of H. zea and H. armigera were collected in maize fields cultivated at the Brazilian Agricultural Research Corporation, Embrapa Maize & Sorghum, in Sete Lagoas (Minas Gerais) and in farmers? cotton fields in Luís Eduardo Magalhães (Bahia), respectively. Bioassays were conducted in the laboratory using individual larvae in 50 mL plastic cups fed a white bean?based artificial diet and maintained at a temperature of 26 ± 2 °C and a relative humidity of 47 ± 10%. The following larval biological parameters were evaluated: number and duration of instars, survival of larval instars and pupae, larval biomass, larval head capsule size, and larval length. An adaptation index was computed for comparison of development of the 2 species. Significant differences were observed between the species for all variables except for the number of instars and pupal survival. Although H. armigera larvae developed faster and were smaller than H. zea larvae, the diet tested can be considered adequate for rearing both species in the laboratory.