The callus culture facilitates the study of factors involved in somatic embryogenesis, technique that allows the production of embryos in vitro from somatic tissue, making the propagation possible of elite plants and constituting an important tool in breeding programs. The objective was to analyze the influence of growth regulators on the formation of callus on cotton cultivars BRS Araripe and BRS Seridó. In the Laboratory of Tissue Culture of Embrapa Algodão, for the induction and proliferation of callus, hypocotyledonary segments were cultured on MS medium supplemented with phytoregulators NAA, KIN and 2,4-D. For the induction of embryogenic callus, it was used redifferentiation medium, with no phytoregulators. Data were analyzed according to the nonparametric chi-square test, being verified high number of potentially embryogenic callus, with a friable consistence and cream-greenish coloration. In the treatment with addition of NAA and KIN was observed the formation of embryogenic callus of BRS Seridó. The dependence of the genotype is a major problem for the low frequency of somatic embryogenesis in cotton that has been achieved in a few cultivars; it is necessary to study in other varieties for the definition of appropriate protocols in this process.

Mycorrhizal fungi has been shown to affect some species of parasitic nematodes, in many cases reducing oviposition and the number of galls on the root system of infected plants. In order to evaluate the biocontrol potential of arbuscular mycorrhizal fungi to reduce the infectivity of Meloidogyne incognita in tomato plants, an experiment was conducted with a randomized block design with eight replications in a factorial with thefollowing treatments: with and without M . incognita, with presence and absence of fungal species Glomus clarum Nicolson & Schenck, Gigaspora albida Schanck & amp; Smith and Acaulospora scrobiculata Trappe. The fungus G. clarum significantly reduced the gall index (46.4%) and the number of egg mass (78.8%) of the nematode on tomato seedlings. The percentage of root colonization is not in itself an indicator of efficiency in controlling fungal infectivity of M. incognita in tomato plants, since A. scrobiculata exhibited a high degree of colonization (77.6%) and was not effective in controlling nematode reproduction. The species of mycorrhizal fungi differ in efficiency in reducing the infectivity of M. incognita in tomato seedlings.

This work aimed to identify the sustainability indicators of the producers in the river Faé, Ceará, watershed. The field analysis was carried out in September 2006, with the application of cross-over forms to the 237 small producers. Through the employment of the Factor Analysis/Principal Component Analysis AF/ACP it was identified that the model of better adjustment to express the sustainability of the watershed Faé was that composed of six factors, explaining 80.25% of the total variance, dissolved before in 12 dimensions. The first factor explained 21.73% of the total variance and it is related with the health of the farmers. The second and third factors presented a close relation with the soil vegetation cover and the irrigation management, responding for 15.57% and 14.82% of the total variance, respectively. The forth factor, explaining 10.18% of the total variance, presents itself as an indicator of the water preservation. The both remaining factor explain, together, 17.95% of the total variation and express the family organization and the agricultural production techniques of the region, respectively. The sustainability of the producers was determined mainly by the health, vegetation coverage conservation and irrigation indicators, expressing the need of practical courses and the action of the rural extension, where the producer will learn agricultural production techniques by doing them.

The present work objectified to detect tendencies of long period in the annual averages of the air temperature. We analyzed minimum, mean, and maximum temperature, absolute minimum, and absolute maximum. Twenty-four meteorological stations on the Northern Northeast (Ceará, Rio Grande do Norte, Paraíba and Pernambuco) were used. We used the historical series from 1961 to 1990. To identify the tendencies, we used the analysis of lineal regression analysis. The Student's t-test was used to verify the statistical of the coefficients of lineal regression. We observed an increase of the minimum, mean, maximum temperature, and absolute minimum. The absolute maximum temperature didn't present significant tendencies of increase nor of decrease. We conclude that has had a decrease of the annual thermal amplitude of the temperature on the Northern Northeast, mainly, due to the increase of the night temperature.

Brazil is the fourth cocoon producer in the world. In São Paulo State there are mulberry some hybrids whose productivity are higher than the commonly cultivated varieties. The objective of this study was to evaluate the effect of mulberry hybrids (Morus spp.) on the cocoon production of silkworm (Bombyx mori L.). The experiment was conducted at the Unidade Regional de Pesquisa de Gália do Instituto de Zootecnia, SP. The caterpillars were fed on leaves of the hybrids IZ-3/2, IZ-13/6, IZ-15/7, IZ-19/13, IZ-56/4, IZ-57/2, IZ- 40, IZ-64, in a rearing hut at 25 oC ± 3 oC and 75% ± 5% relative humidity. 'Korin' was used as standard. The hybrids affected the duration of the larval period and the weight of the caterpillars, prepupaes and the silk glands as well. There was a reduction in the duration of larval development when the caterpillars had been fed with hybrid IZ-56/4 and the 'Korin' variety. Hybrids IZ-57/2, IZ-56/4 and IZ-15/7 presented the highest cocoon production.