The objective of this work was to verify the influence of light environments combined with rhizobia inoculation on cowpea growth and productivity. A completely random design was used in a 4x4 factorial scheme, with four light environments, four nitrogen sources and eight replicates in split plot parcels. Light environments were set by means of photo-conversion and thermo-conversion nettings (Aluminet®, red net and black net) and control treatment without shading (full sun). Nitrogen sources were constituted by the strains INPA 03-11B - SEMIA 6462 (Bradyrhizobium elkanni) and UFLA 03-84 - SEMIA 6461 (Bradyrhizobium viridifuturi), and two control treatments: with 70 kg ha-1 of mineral nitrogen and without N. Plant height, indices of chlorophyll a, b and total chlorophill, the number of leaves, number of nodules, dry matter of nodules, dry matter of the aerial portion, dry matter of roots and total dry matter, relative efficiency, gathering of nitrogen in the aerial portion, number, length and matter of pods per plant and dry matter of 100 grains, were evaluated. . There was interaction between light conditions and nitrogen sources for the number of nodules. Individual effect was observed in all other variables. Strain INPA 03-11B was able to promote higher nodulation in cowpea plants in light environments under full sun and Aluminet and the strain UFLA 03-84 only under full sun conditions. However, the efficiency of diazotrophic bacteria to promote vegetative growth, nitrogen gathering and production was not influenced by different light environments. Thus, full sun cultivation is recommended, independently of the nitrogen source used.

No abstract

The objective of this study was to evaluate the effect of artificial defoliation on vegetative and productive stages of cowpea inoculated with diazotrophic bacteria, in two experiments. The first experiment was performed in a greenhouse with 5 × 5 factorial (five defoliation percentages and five N sources), with four repetitions. N sources consisted of bacterial inoculation with strains INPA 03-11B, UFLA 03-84, UFRB FA34C2-2, and two control treatments: i - with N fertilization and ii - blank control, without N fertilization and without inoculation. The second experiment was performed in the field, in a 3 × 5 factorial scheme, with three repetitions. Treatments consisted of three N sources: with N fertilization, with bacterial strain INPA 03-11B that was selected in the first experiment, and five percentages of artificial defoliation. Defoliation percentages for both experiments were 0, 25, 50, 75, and 100%. Artificial defoliation during the vegetative stage caused reduction in the dry mass of bacterial nodules. Inoculation increased plant tolerance to defoliation and enhanced grain nutrient concentration (N and P). Inoculation with the strain INPA 03-11B allowed cowpea plants to tolerate 50% defoliation in the vegetative stage. The mean productivity of cowpea was reduced under > 50% defoliation during the productive stage; therefore, control of defoliating pests until the productive stage is not necessary under field conditions.

Efeito alelopático do extrato foliar de eucalipto na germinação de sementes de tiririca (Cyperus rotundus L.)Allelopathic effect of eucalyptus foliar extract on germination of seed of tiririca (Cyperus rotundus L.

The objective of this study was to evaluate the agronomic efficiency of rhizobia strains already approved or in the selection stage for cowpea, in the Recôncavo da Bahia region, Brazil. Two field experiments were performed in the municipalities of Cruz das Almas and Maragogipe, Bahia, Brazil. A randomized block design was used with seven nitrogen sources and four replicates. Nitrogen sources consisted of the strains UFRB FA51B1, UFRB BA72C2-1, UFLA 03-164T, UFLA 03-84, INPA 03-11B, and two controls without inoculation, one with mineral nitrogen and another without. All the strains nodulated cowpea. The efficiency of the strains was determined by the number of nodules, nodule dry matter, total dry matter, grain yield, nitrogen accumulation in shoots and grain, and relative efficiency. The strain UFLA 03-164T can be recommended for biomass production, green manure, and promotion of grain yields in both soils. In Maragogipe, the UFLA 03-84 and INPA 03-11B strains can be recommended for biomass production, green manure, and promotion of grain yields. The UFLA 03-164T strain showed great potential to promote and grain yield in the two municipalities studied. The strain INPA 03-11B can be recommended for Maragogipe soil. UFLA 03-84 can also be recommended to increase grain yield in Cruz das Almas.

ABSTRACT Inoculating crops with diazotrophic bacteria constitutes a feasible biotechnological tool to reduce or even avoid the use of nitrogen fertilizers and to improve the nutritional status of crops. However, the potential use of such technology is limited due to the lack of studies in diverse vegetable crops. We evaluated the production of chicory (Cichorium intybus) in response to inoculation with diazotrophic bacteria in two soil classes. The experiments were performed under greenhouse conditions and under a completely randomized design. The treatments were constituted by strains UFRB FA34C2-2, UFLA 03-84 and INPA 0311B, and two control treatments (devoid of bacterial inoculation and with and without nitrogen fertilization). Two experiments were carried out, one using a soil classified as a dystrophic yellow Latosol (Oxisoil) and one using a Quartsandy Neosol (Typic Quartzipsamment). Chlorophylls a, b and total; plant height; number of leaves; dry mass of the aerial portion; dry mass of roots; total dry mass; effectiveness; efficiency in addition to N and P gathering in the aerial portion, were evaluated 60 days after seeding. The inoculation with diazotrophic bacteria resulted in adequate production when compared to the control treatment without nitrogen fertilization and without inoculation. Diazotrophic bacteria showed potential supplying nitrogen to chicory plants and spare the use of nitrogen fertilization in both soil classes. The strain INPA 0311B, recommended for cowpea, promoted vegetal growth and increased the dry weight of the aerial portion in chicory, under both dystrophic yellow Latosol (Oxisoil) and Neossolo Quartzarênico (Typic Quartzipsamment), when cultivated under greenhouse conditions.