Symbiotic capability of calopo rhizobia from an agrisoil with different crops in Pernambuco

Abstract

SUMMARYBiological nitrogen fixation by rhizobium-legume symbiosis represents one of the most important nitrogen sources for plants and depends strongly on the symbiotic efficiency of the rhizobium strain. This study evaluated the symbiotic capacity of rhizobial isolates from calopo (Calopogonium mucunoides) taken from an agrisoil under Brachiaria decumbens pasture, sabiá (Mimosa caesalpiniifolia) plantations and Atlantic Forest areas of the Dry Forest Zone of Pernambuco. A total of 1,575 isolates were obtained from 398 groups. A single random isolate of each group was authenticated, in randomized blocks with two replications. Each plant was inoculated with 1 mL of a bacterial broth, containing an estimated population of 10 8 rhizobial cells mL -1 . Forty-five days after inoculation, the plants were harvested, separated into shoots, roots and nodules, oven-dried to constant mass, and weighed. Next, the symbiotic capability was tested with 1.5 kg of an autoclaved sand:vermiculite (1:1) mixture in polyethylene bags. The treatments consisted of 122 authenticated isolates, selected based on the shoot dry matter, five uninoculated controls (treated with 0, 50, 100, 150, or 200 kg ha -1 N) and a control inoculated with SEMIA 6152 (=BR1602), a strain of Bradyrhizobium japonicum. The test was performed as described above. The shoot dry matter of the plants inoculated with the most effective isolates did not differ from that of plants treated with 150 kg ha -1 N. Shoot dry matter was positively correlated with all other variables. The proportion of effective isolates was highest among isolates from sabiá forests. There was great variation in nodule dry weight, as well as in N contents and total N. Index terms: Calopogonium mucunoides, biological N fixation, forage legumes, tropical legumes.(

Prospecting of efficient rhizobia for peanut inoculation in a Planosol under different vegetation covers

“…This has also been observed for rhizobia isolates, inoculated in other legumes (Lima et al, 2012;Calheiros et al, 2013). Such variability in symbiotic system which has the ability of collections of rhizobia, is a result of high biodiversity of these microorganisms, associated with biotic and abiotic factors.…”

“…In recent years, prospecting of effective rhizobia for the inoculation of various legumes has been carried out in Brazilian soils, yielding promising results for calopo (Calheiros et al, 2013;Calheiros et al, 2015), velvet bean (Lima et al, 2012) and cowpea (Chagas Junior et al, 2010), among others. Nonetheless, few studies have evaluated the efficiency of peanut isolates (Hoffman et al, 2007;Torres Júnior et al, 2014;Sizenando et al, 2016).…”

Agronomic effectiveness of rhizobia strains on cowpea in two consecutive years

“…Therefore, the nodulation of cowpea with effective rhizobia may represent an important strategy to increase the interest to adopt the nitrogen fixation system. In recent years, the evaluation of effective rhizobia on various legumes have been increased and are conducted in the Brazilian Northeast with the promising results obtained for various legumes as described by Calheiros et al (2013Calheiros et al ( , 2015 for calopo; Lima et al (2012), for velvet beans, Torres Junior et al (2014) and Santos et al (2017) for peanuts, among others important species. However, few studies were carried out to evaluate the symbiotic effectiveness to increase cowpea yield by inoculation with specific strains of the Brazilian Northeast (Farias et al, 2016b).…”

Symbiotic Effectiveness and Competitiveness of Calopo Rhizobial Isolates in an Argissolo Vermelho-Amarelo Under Three Vegetation Covers in the Dry Forest Zone of Pernambuco

“…Ideally a large number of strains should be included in these stages, to increase the chance of finding higher efficiency strains for inoculant production (Lima et al, 2009;Chagas Junior et al, 2010;Rufini et al, 2011;Araújo et al, 2012;Calheiros et al, 2013).…”