Does inoculation with Rhizobium tropici and nitrogen fertilization increase chickpea production?

Abstract

Studies related to nitrogen fertilization and biological nitrogen fixation in the increase of chickpea production are considered scarce in tropical regions. This work aimed to evaluate the inoculation with Rhizobium tropici, and nitrogen fertilization, under irrigated tropical conditions, on the development of chickpea in low and high content of soil organic matter (SOM). The experimental design was in randomized blocks, with four replications, in a 2 x 6 factorial scheme. Treatments, consisted of the presence and absence of inoculation with R. tropici, and six N doses (0, 25, 50, 75, 100, and 125 kg ha-1) in the form of urea. The study was divided into two areas with distinct contents of SOM. In the area with the lowest content of SOM (3.55 dag kg-1), the inoculation with R. tropici or the fertilization with 125 kg ha-1 N increased the leaf content of nutrients (N, K, Mg, and P) and grain mass per plant, 100-grain mass, number of pods with two grains, dry mass of leaves, branches, chlorophyll index, and relative agronomic efficiency. Thus, the yield was increased in 65%, compared to the control treatment, recommending the application of 100 to 125 kg ha-1 of N with or without R. tropici. In the area with the highest content of SOM (7.37 dag kg-1), the inoculation with R. tropici provided a higher grain mass per plants, number of pods with one gain, dry mass of leaves, total dry mass, and chlorophyll index; nitrogen fertilization increased the leaf content of N and the chlorophyll index, although neither factor interfered with the yield, and are not recommended. Such results indicate the dependence of the nitrogen fertilization and inoculation with Rhizobium on the natural availability of N in the SOM.

Inoculation of Bacillus spp. and nitrogen levels increase chickpea production

“…Soils historically cultivated with chickpea and rich in SOM show high mineral N contents. Chickpea plants show a high deposition of leaves rich in N (Joshi et al, 2019), in addition to high natural N availability (Romanyà;Casals, 2019;Almeida Neta et al, 2020).…”

“…Different results between cultivation areas occurred due to variations in soil fertility, SOM content, pH, and biological diversity (Almeida Neta et al, 2020). High soil fertility and pH favor the activity of Bacillus spp.…”

“…The Brazilian semi-arid is a favorable region for the cultivation of this legume (Artiaga et al, 2015;Nascimento et al, 2016), with yields above 2,700 kg ha -1 in irrigated systems (Hoskem et al, 2017;Pegoraro et al, 2018;Almeida Neta et al, 2020;Fonseca et al, 2020). However, high chickpea yields depend on a balanced nitrogen supply (N) and the presence of growth-promoting bacteria.…”

“…In chickpea cultivation, studies on the inoculation of Bacillus spp. under Brazilian tropical conditions as well as on plant response after mineral nitrogen (N) application are scarce (Amaral et al, 2018;Almeida Neta et al, 2020). N is considered an essential nutrient for legume crops without high symbiotic efficiency.…”