ResumoO objetivo do trabalho foi avaliar o efeito da interação entre a inoculação com rizóbio e a adubação nitrogenada de plantio no feijoeiro (Phaseolus vulgaris L.). Os experimentos de campo com a cultivar Ouro Negro, nas épocas da seca e das águas, tiveram três tratamentos: inoculação e adubação nitrogenada no plantio (20 kg ha -1 de N), apenas a inoculação no plantio, e apenas a adubação nitrogenada no plantio (20 kg ha -1 de N). Todos os tratamentos receberam adubação de cobertura com 40 kg ha -1 de N. No florescimento, avaliou-se a massa seca de parte a aérea e de raiz e o número e massa seca de nódulos. Obteve-se maior massa seca de parte aérea no tratamento adubado e inoculado, sendo o número e massa seca de nódulos similares ao tratamento só inoculado, nas duas épocas de plantio. Na maturação, nas duas épocas, a maior produtividade de grãos e o maior número de vagens e de grãos por planta, foram obtidos no tratamento adubado e inoculado, sendo que os tratamentos só inoculado e só adubado não diferiram significativamente. Portanto, a inoculação de rizóbios no plantio pode substituir a adubação nitrogenada com 20 kg ha -1 de N no plantio sem perda de produtividade. Além disto, a inoculação com rizóbios, acrescida da adubação com 20 kg ha -1 de N no plantio, não inibiu a nodulação e propiciou acréscimo de produtividade. Palavras-chave: Nodulação, Phaseolus vulgaris, Rhizobium, produtividade AbstractThis work has the objective of evaluating the effects of the interaction between inoculation with Rhizobium strains and nitrogen fertilization at sowing on common bean (Phaseolus vulgaris L.) crop. The field experiments with the cultivar Ouro Negro, at dry and rainy seasons, had three treatments: inoculation and sowing N fertilization (20 kg ha -1 of N), only the inoculation, and only sowing N fertilization (20 kg ha -1 of N). Every treatment received 40 kg ha -1 of N by covering. At flowering, the shoot and root dry weight and nodules number and dry weight were evaluated. The higher shoot dry weight was obtained for the inoculation and sowing N fertilization treatment, with similar number and dry weight of nodules of the only inoculation treatment, for both seasons. At the maturity, the higher grain yield, number of pods and grains per plant, were obtained for the inoculation and sowing N fertilization treatment, whereas only inoculation and only sowing N fertilization treatments were not significantly different. Therefore, inoculation can substitute sowing N fertilization with 20 kg ha -1 of N with the same yield. Also, the sowing N fertilization together with inoculation did not inhibit nodulation and improved yield.

SUMMARYTwo field experiments were conducted during the rainy seasons of 2013 and 2014 to evaluate the effects of biological nitrogen fixation (BNF) and/or sowing N fertilization on the growth and yield of Phaseolus vulgaris L. In addition, leaf soluble protein content (LSPC) was measured at four growth stages in both seasons. Plants were subjected to the following treatments: only fertilized with 20 kg N ha−1 at sowing and with 40 kg N ha−1 at 25 days after emergence (DAE) (F); only inoculated with Rhizobium tropici strain SEMIA 4080 at sowing and fertilized with 40 kg N ha−1 at 25 DAE (I+N); and inoculated and fertilized with 20 kg N ha−1 at sowing and with 40 kg N ha−1 at 25 DAE (IF). An additional treatment was done only in the second season and plants were inoculated with no N fertilization at any phase (I−N). Crop growth rate and leaf area index were enhanced by IF and F treatments as compared to I+N treatment, however, net assimilation rate did not differ among the treatments. At the pollination and flowering stages for seasons, LSPC was significantly increased by IF treatment, which also caused the highest final yield compared with the remaining treatments in both seasons. Therefore, the fertilization with 20 kg N ha−1 at sowing together with inoculation and 40 kg N ha−1 at 25 DAE is recommended for obtaining high yield in bean cultivation with high technology. As the inoculation with Rhizobium at sowing and fertilization with 40 kg N ha−1 at 25 DAE (I+N) had the same crop yield as plants fertilized at sowing and at 25 DAE (F), it can be recommended for a low-cost technology cultivation employed by small farmers.

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-The objective of this work was to evaluate the growth and yield of cowpea grains in different intercropping systems with millet, in wet and dry seasons. The experiments were performed in the experimental field of the Department of Plant Science of the Federal Rural University of Rio de Janeiro, Brazil, using a randomized block design with three replications and five treatments: T1-sole crop of millet; T2-sole crop of cowpea; T3-intercrop of millet (1 row) and cowpea (1 row) with 0.5 m between rows (1Mx1C-0.50); T4 -intercrop of millet (1 row) and cowpea (1 row) with 0.75 m between rows (1Mx1C-0.75); and T5 -intercrop of millet (1 row) and cowpea (2 rows) with 0.5 m between rows (1Mx2C-0.50). The cowpea shoot dry weight, root dry weight, number and dry weight of nodules, grain yield and 1000-grain weight, and the millet fresh weight, shoot dry weight, grain yield and 1000-grain weight were evaluated. The land-use efficiency index (LUE) showed significant differences in yield between the sole crop of cowpea and the intercropping system, with greater grain weight in the intercrop 1Mx2C-0.50. On the other hand, the intercrop 1Mx1C-0.75 was not recommended for the study conditions. CRESCIMENTO E PRODUTIVIDADE DE GRÃOS DO FEIJÃO-CAUPI NOS CULTIVOS SOLTEIRO E CONSORCIADO COM MILHETORESUMO -O objetivo do trabalho foi avaliar o crescimento e a produtividade de grãos do feijão-caupi nos diferentes sistemas de consórcio com o milheto, na época das águas e da seca. Os experimentos foram conduzidos no campo experimental do Departamento de Fitotecnia, da Universidade Federal Rural do Rio de Janeiro, em delineamento em blocos ao acaso, com três repetições e cinco tratamentos: T1-cultura solteira de milheto; T2-cultura solteira de feijão-caupi; T3-consórcio com uma linha de milheto e uma de feijão-caupi espaçadas de 0,5m (1M x 1C-0,50); T4-consórcio com uma linha de milheto e uma de feijão-caupi espaçadas de 0,75m (1M x 1C-0,75); e T5-consórcio com uma linha de milheto e duas de feijão-caupi espaçadas de 0,5m (1M x 2C-0,50). No feijão-caupi, avaliou-se a massa seca da parte aérea, massa seca de raiz, o número e massa seca de nódulos, a produtividade de grãos e a massa de 1000 grãos; enquanto no milheto, avaliou-se a massa verde, a massa seca da parte aérea, a produtividade de grãos e a massa de 1000 grãos. Pela comparação do índice de equivalência de área (IEA), se verificou diferenças significativas na produção de feijão-caupi por área explorada, no sistema consorciado em relação ao cultivo solteiro, com a maior massa de grãos no consórcio 1M x 2C-0,50, em relação aos outros. Por outro lado, o consórcio 1M x 1C-0,75 não é recomendável para o local. Palavras-chave:Vigna unguiculata L.. Penisetum glaucum (L.) R. Brown. Produção. Índice de equivalência de área.

The chlorophyll a fluorescence parameters of four Phaseolus vulgaris L. genotypes were evaluated under drought in two greenhouse experiments. Under severe water stress, the thermotolerant genotype 'Diplomata' maintained significantly higher values of predawn leaf water potential (Ψw), maximum Fv/Fm and effective (ΦPSII) quantum yield of photosystem II , and non-photochemical quenching than 'Ouro Negro', in the first experiment, and 'A 285' and 'A 222', in the second one. Among these parameters, Fv/Fm showed more differences that discriminated between the genotype responses even when measured at night. Next, a difference between Fv/Fm after sundown and Fv/Fm at dawn on the same day (day ∆Fv/Fm), i.e., the intensity of photoinhibition, and a difference between Fv/Fm at dawn and Fv/Fm after sundown on the day before (night ∆Fv/Fm), i.e. the photoinhibition recovery, were evaluated. Day ∆Fv/Fm and night ∆Fv/Fm were significantly higher for 'Diplomata' under severe water stress in both experiments. In addition, 'Ouro Negro' in the first experiment and all the genotypes in the second showed negative values of night ∆Fv/Fm on the last day of drought when their Ψw were also minimal indicating no recovery from photoinhibition and the need for rehydration. At maturation, stressed plants of 'Diplomata' showed a significantly higher yield than 'Ouro Negro' in the first experiment and the same as 'A 285' in the second. Therefore, the thermotolerant genotype 'Diplomata' also showed drought tolerance, and the use of day ∆Fv/Fm and night ∆Fv/Fm fluorescence analysis was able to discriminate between the tolerances of these genotypes and to indicate the need for rehydration.