Seleção de rizóbios para feijão-caupi resistentes à salinidade do solo oriundos do brejo paraibano.

Abstract

Cowpea (Vigna unguiculata L. Walp) is one of the main sources of food and income for family farmers in the northeastern semiarid. However, its productivity is relatively low, since beans are grown in conventional systems with low technological use. The use of inoculants can reduce this impact, increasing productivity gains. Therefore, the objective of this work was to evaluate rhizobia isolates for cowpea resistant to soil salinity from the Brejo Paraibano. The test was conducted at the Soil Microbiological Research Unit, belonging to the Department of Soils and Rural Engineering, of the Agricultural Sciences Center, of the Federal University of Paraíba and located in the municipality of Areia-PB. The rhizobiaisolates for cowpea are part of the collection of the Center of Agricultural Sciences of the Federal University of Paraíba. The experimental design was completely randomized (DIC), with 10 treatments and 5 repetitions: T1- UPMS/UFPB VU05; T2-UPMS/UFPB VU01; T3- UPMS/UFPB VU12; T4- UPMS/UFPB VU14; T5- Nitrogen; T6- UPMS/UFPB VU04; T7- UPMS/UFPB VU08; T8- Recommended (03-84-6/2010); ; T9- UPMS/UFPB VU31; T10- Witness (autoclaved soil). The seeds were disinfected, inoculated and sown on a substrate based on sieved soil and autoclaved in PET bottles with a capacity of 0.5 dm-3 , with an experimental unit corresponding to two plants per pot. 35 days after plant emergence, the following variables were evaluated: plant height,, number of leaves, leaf size, weight of green and dry matter, number of nodules, green and dry weight of nodules, nitrogen accumulation in the aerial part, relative fixation index and growth in saline with KCl and NaCl The averages were compared using the Scott Knott test (p<0.01). It was concluded that inoculation with different strains of native rhizobia did not have a significant effect on the variables nitrogen accumulation in the aerial part, plant height, green mass weight, dry mass weight, number of leaves and leaf size. The inoculation with native strains was significant for the number of nodules, weight of green nodules, weight of dry nodules and relative efficiency index of nitrogen fixation. The UPMS/UFPB strains VU08, VU12 and VU31 showed higher resistance to KCl and NaCl concentrations in culture midh.