Groundnut (Arachis hypogaea L.) is an important food legume in tropical and subtropical areas because of its ability to adapt to a wide range of agro-climatic regions. Groundnut is usually cultivated in nutrient-poor soil and rain-fed conditions, so average yield tends to be very low relative to potential yield. Even though the nitrogen (N) requirement of groundnut is much higher than cereals due to its high protein content, it has the capacity to meet 60-80% of N-based requirements through symbiotic N fixation via its root nodules. In its symbiotic relationship with legumes, Rhizobium fixes N, thereby positively impacting the content of this nutrient. This study aimed to isolate, characterize and purify microbial strains of Rhizobium specific to groundnut in a bid to increase this legume’s productivity. The research was conducted in the AICRP-Groundnut laboratory and greenhouse of the Directorate of Research, BCKV, in Kalyani, India during October 2016 to March 2017. Two Rhizobium isolates (RhBC and NRA1) were isolated and selected from groundnut pot cultures. After 45 days, NRA1 produced higher plant biomass, longer roots and shoots, more nodules and higher nodule dry weight than RhBC. NRA1 was selected for a future field trial. The two isolated microbial strains will aid in the screening of additional local isolates to test their effectiveness when co-cultured with local groundnut cultivars to increase yield in soil with low fertility.
Present study was designed to assess the prospect of fresh phosphate solubilizing bacterial isolates (PSB), to ones, used as PSB-biofertilizer in growth promotion of groundnut (Arachis hypogaea L.). Phosphate-solublizing index (PSI) of 17 isolates varied from 1.692 to 3.033, after seven days incubation. Tricalcium phosphate solubilization by PSB ranged from 309.72 to 615.28 ìg/ml and highest value was recorded for isolate JCA-5. Three most efficient fresh isolates were clustered under the genera Burkholderia, Bacillus and Brevibacillus. The supplementation of elite PSB isolates augmented growth and P-uptake irrespective of edaphic conditions for groundnut. Steady increments in root (22.6% and 25.5%) and shoot length (27.6% and 33.7%), root dry-weight (20.3% and 16.2%),shoot dry-weight (11.3% and 23.3%) and P-uptake (30% and 67%) of groundnut was evident in red-laterite soil and new alluvial soils respectively in comparison to the previously acknowledged PSB biofertilizers.
A field experiment was conducted during <italic>kharif</italic> season of 2005 and 2006 to find out the plant density and fertility levels of <italic>kharif</italic> groundnut (<italic>Arachis hypogaea</italic>) – pigeon pea (<italic>Cajanus cajan</italic>) intercropping system. Growing of groundnut as sole crop recorded higher pod yield (1490 kg ha<sup>−1</sup>) over groundnut in intercropping system. The highest pod yield (889 kg ha<sup>−1</sup>) of groundnut among the intercropping system was obtained with the treatment received 100 % of both RDF and plant density of groundnut and pigeon pea respectively. Which was closely followed by T<sub>9</sub> (850 kg ha<sup>−1</sup>), T<sub>2</sub> (846 kg ha<sup>−1</sup>), T<sub>11</sub> (828 kg ha<sup>−1</sup>) and (825 kg ha<sup>−1</sup>) and they were statistically at par among each other. Growing of pigeon pea as sole crop recorded higher <sup>T</sup>10 grain yield (1584 kg ha<sup>−1</sup>) over pigeon pea in intercropping system. Among the intercropping system the maximum pigeon pea grain yield was found in T<sub>1</sub> (1013kg ha<sup>−1</sup>) which was at par with T<sub>10</sub> (978 kg ha<sup>−1</sup>), T<sub>11</sub> (950 kg ha <sup>−1</sup>), T<sub>2</sub> (946 kg ha<sup>−1</sup>), T<sub>9</sub> (939 kg ha<sup>−1</sup>), and T<sub>5</sub> (903 kg ha<sup>−1</sup>). Among the cropping systems, intercropping of groundnut with pigeon pea resulted in maximum groundnut equivalent yield (2155 kg ha<sup>−1</sup>) in T<sub>1</sub>. Among the intercropping systems, groundnut with pigeon pea in 4:2 row proportions with 100% both plant density and RDF in all the crops was most remunerative in respect of net return (Rs.28400) and economic return: cost ratio (2.85).
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The results obtained from analysis of variance showed that there was significant difference (P < 0.05) between the genotypes in terms of days to first flowering, days to maturity, 100-kernels weight, shelling percentage, sound matured kernel, and pod yield. The recorded data matrix on seven morphological traits were employed for Non-hierarchical Euclidean cluster analysis based on square Euclidian distance by Un-weighted Paired Group Arithmetic Average method. The 21 genotypes were grouped into four distinct non-overlapping clusters in a random sequence, indicating the presence of high dimension of genetic diversity. Pod yield as an economically important trait was found to be the key contributor towards the genetic divergence followed by days to maturity. Based on magnitude of divergence and performance towards yield and yield attributes, five genotypes (TG-75, AK-343, ICGV-07038, Girnar-3 and TCGS-1157) were selected for exploitation as parents in future breeding programs. Based on high yielding genotypes and large inter-cluster distances, a trial on crossing of the genotypes from cluster II with the genotypes of clusters IV and III, genotypes from cluster I with II emphasizing on selected five genotypes could result in wide spectrum of promising genetic variability, aiming at enhancement of groundnut yield.
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