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Studies in the Amazon indicate a wide diversity of rhizobia with the ability for biological nitrogen fixation (BNF), which could expand the number of strains approved for cowpea. Thus, the aim of this field study was to evaluate the agronomic performance in cowpea of the several strains isolated from the soils of the Brazilian states Acre and Rondônia, and to compare them with strains approved by the Ministry of Agriculture (MAPA) and with non-inoculated controls (without and with mineral nitrogen fertilizer). The inoculants performed well. Though less effective than the other strains, the UFLA 03-36 strain also was prominent with respect to grain yield. Because of the positive response of the UFLA 03-129 strain, which led to yield increases greater than the obtained from the control without inoculation plus mineral-N, it can be recommended as an inoculum for cowpea. Further investigations should be carried out to obtain MAPA's approval for their use. Other experiments involving this strain and several cultivars are being carried out on other types of soil and environmental conditions of the state of Minas Gerais. [ABSTRACT FROM AUTHOR]

Although the use of inoculants containing rhizobia is encouraged, there are no official recommendations for inoculation of snap bean. In this respect, the aim of this study was to evaluate the agronomic performance of Rhizobium strains in symbiosis with snap bean cultivars with different growth habits and crop cycles. The experiment was carried out in pots with soil in a greenhouse in the spring-summer season in Lavras, state of Minas Gerais, Brazil. A completely randomized experimental design was used, with 4 replications, in a 4 × 7 factorial arrangement involving four snap bean cultivars and seven treatments - five strains of Rhizobium (UFLA 02-100, UFLA 02-127, UFLA 04-173, CIAT 899, and PRF 81), plus two controls without inoculation (with and without 500 mg N-NH4NO3·dm-3). We conclude that: i) while genetic differences were observed among cultivars with respect to nodulating capacity, in all cases significant benefits were observed from BNF inoculation and ii) inoculation with selected strains of Rhizobium, as well as fertilization with mineral N, favors plant growth, snap bean yields, and accumulation of N in the pods and, therefore, can fully substitute nitrogen fertilization in snap bean grown under protected cultivation. [ABSTRACT FROM AUTHOR]

Cowpea is a very important crop to Brazilian Semi-Arid mainly small family-based farmers. Rhizobia inoculation is a practice, easy to use, and cheap technology that increases cowpea productivity. The aim of this study was to evaluate the efficiency of two new rhizobia isolates in greenhouse and field as well as classify them taxonomically. To bacterial identification the 16S rRNA gene of ESA 17 and ESA 18 isolates were sequenced. The greenhouse test was conducted with pots containing 3 L of soil and the bacterial isolates evaluated were ESA 17, ESA 18, BR 3267 or BR 3262 strains. A field experiment was implemented on a Vertisol in Juazeiro, Bahia State, to evaluate the cowpea growth and productivity. In this experiment, the peat-based inoculants with ESA 17, ESA 18, BR 3267 or UFLA 3-84 were used in 2 cowpea cultivars. Both bacteria were identified as Bradyrhizobium, but related to different species. ESA 17 was related to B. japonicum and ESA 18 was closer to B. pachyrhizi. At greenhouse, both isolates increased cowpea nitrogen content in the shoots due to the presence of very efficient nodules. In the field, the isolate ESA 18 inoculated at BRS Pujante cultivar induced higher production than observed for the absolute control, and for BR 17 Gurguéia cultivar, the ESA 17 and BR 3267 stood out both by inducing high production and grain protein content. The results indicate that both isolates can be evaluated in network experiments aiming at official recommendation for new bacteria to cowpea inoculant in Brazil. [ABSTRACT FROM AUTHOR]

Large soybean yield gaps on smallholder farms in Kenya are associated with multiple soil constraints, including nutrient depletion, low organic matter, and soil acidity. Integrated nutrient management practices are necessary to increase productivity, particularly on degraded course-textured soils. [ABSTRACT FROM AUTHOR]