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Boron (B) deficiency is the leading constraints in chickpea production in calcareous soils; albeit the range between B deficiency and toxicity is very narrow. Boron-tolerant bacteria (BTB) can optimize plant functions under B-deficient conditions by improving its uptake and can also tolerate B toxicity. This two-year pot study was conducted to optimize the best level of B as foliar application along with BTB (Bacillus sp. MN54) inoculation to improve nodulation, yield and grain-B concentration of chickpea. Two sets of pots, one with BTB inoculation and other without BTB were prepared. Foliar treatments of B were applied to plants at concentrations of 0.000, 0.023, 0.046, 0.069, and 0.092 M while plants sprayed with distilled water were taken as control. Boron application improved root and growth-related traits, nodulation, yield-related traits and grains-B concentration compared with no B and water spray controls. Among levels tested, foliar application of 0.046 M B solution was better in improving root system, nodulation, yield-related traits; while higher B levels resulted more grains-B concentration. Seed inoculation with BTB further augmented chickpea productivity compared to non-inoculation controls. Foliar application of B (0.046 M) coupled with BTB enhanced number of grains per plant (40%), nodules population (60%) and grain yield (43%) compared with control. Lower levels of B (≤0.069 M) seemed good to improve yield-related traits while its higher levels improved grains-B concentration. In crux, foliar application of 0.046 M B solution along with seed inoculation with BTB (Bacillus sp. MN54) seemed a pragmatic option to improve nodulation, yield and grains-B concentration of chickpea. [ABSTRACT FROM AUTHOR]

Chickpeas are rich source of protein and predominantly grown in boron (B)-deficient sandy-loam soils in Pakistan. Boron-tolerant bacteria (BTB) could tolerate higher B levels in soil and increase B availability to the plants. Field trials were conducted under irrigated (district Layyah) and rainfed (district Chakwal) conditions to evaluate the interactive effects of pre-optimized B application methods and BTB (Bacillus sp. MN54) on the nodule's population, grain quality, productivity, and grain-B concentration in desi chickpea during 2019–2020 and 2020–2021. Boron was applied as soil application (1 kg B ha−1), foliar application (0.025% B), osmopriming (0.001% B), and seed coating (1.5 g B kg−1 seed) with or without BTB inoculation. Untreated seeds receiving no B through any of the methods were regarded as control. The individual and interactive effects (up to three-way interaction of location × BTB inoculation × B application methods) of year, location, B application methods and BTB inoculation significantly altered the growth and yield-related traits of desi chickpea. The four-way interaction of year × location × BTB inoculation × B application methods was non-significant for all recorded growth and yield-related traits. Regarding individual effects, the higher values of growth and yield-related traits were noted for 2020–2021, rainfed location, BTB inoculation and B application through seed priming. Similarly, in two-way interactions 2020–2021 with rainfed location and BTB inoculation, rainfed location with BTB inoculation and osmopriming and osmopriming with BTB inoculation recorded higher values of the growth and yield-related traits. Osmopriming combined with BTB inoculation significantly improved dry matter accumulation and leaf area index in both locations. Boron application through all the methods significantly improved grain quality, yield grain B concentration. The highest grain and biological yields, and nodules' population were recorded with osmopriming followed by soil application of B combined with BTB inoculation. The highest plant B concentration (75.05%) was recorded with foliar application of B followed by osmopriming (68.73%) combined with BTB inoculation. Moreover, the highest economic returns (USD 2068.5 ha−1) and benefit–cost ratio (3.7%) were recorded with osmopriming + BTB inoculation in 2020–2021 under rainfed conditions. Overall, B application through osmopriming and soil application combined with BTB inoculation could be used to increase productivity and profitability of desi chickpea, whereas foliar application is a better method to enhance grain and plant B concentration. [ABSTRACT FROM AUTHOR]

Context: The production of chickpea (Cicer arietinum L.) is negatively affected by boron (B) deficiency. In Pakistan, the crop grown under B deficiency produces grains with low B concentration. Application of B-tolerant bacteria (BTB) is a promising option to improve B supply to plants grown under B deficiency. Aims: This study was focused on determining the appropriate concentration of B for seed priming, and its effects with BTB inoculation on growth, productivity and grain B concentration of chickpea. Methods: Chickpea seeds were primed in aerated solutions of B concentrations in the range 0.01–0.5% (w/v), with hydroprimed and dry seeds as controls. Concentrations >0.1% proved toxic and seeds failed to germinate. Hence, B was further diluted to concentrations in the range 0.0001–0.1%. Pots containing chickpea seeds were divided into two sets having all B treatments. One set was inoculated with BTB (5 mL per pot of pure Bacillus sp. MN54 culture at 10 9 cfu mL−1); the other set was not inoculated. Key results: Seed priming with B along with BTB inoculation improved stand establishment, growth, nodulation, yield and grain B concentration of chickpea. Seed priming treatments with B at 0.001% and 0.0001% along with BTB inoculation were most effective for improving stand establishment, seedling growth and grain yield, whereas 0.1% B was more effective for improving grain B concentration. Conclusions: Seed priming with 0.001% B along with inoculation of Bacillus sp. MN54 improved seed germination, nodulation, yield and grain B concentration of chickpea under B-deficiency conditions. Implications: Seed inoculation with BTB i.e., Bacillus sp. MN54 coupled with seed priming in 0.001% B solution is a viable option to improve yield and grain B concentration of chickpea grown on B-deficient soils. Boron (B) deficiency is the leading constraint to chickpea productivity in Pakistan. Results of this study elucidated that B seed priming at lower rates (0.001% and 0.0001%) along with seed inoculation with B-tolerant bacteria (Bacillus sp. MN54) improved the productivity and grain-B biofortification of chickpea. Higher levels of B seed priming (>0.1% B solution) proved toxic, with no germination recorded. [ABSTRACT FROM AUTHOR]