Genetic Variability and G×E Interactions in a Diverse Set of Groundnut Accessions

Background: Knowledge of the genetic diversity for various agronomic traits and their interaction with the environment and subsequent classification of genotypes will be beneficial for identification of divergent and stable sources of agronomic traits. Methods: A set of 96 groundnut germplasm accessions belonging to four botanical groups were evaluated for three years (2017 to 2019) for pod yield and component traits using AMMI analysis and subsequently accessions were classified based Euclidean cluster analysis. Result: Among different botanical groups, Virginia genotypes matured late and possessed high SPAD chlorophyll meter readings (SCMR) and pod yield compared to Spanish types. The component traits of pod maturity like days to flowering (first and 50%) showed low heritability and high genotype × environment interaction (GEI) and significant negatively affected sound mature kernel (SMK) and shelling per centage (SP). The cumulative contribution of environment and GEI component to the total variance was the highest in the expression of SP (67%) followed by days to maturity (54%) and days to 50% flowering (52%). Euclidean distance-based cluster analysis grouped the 96 accessions into five major clusters. Cluster I had accessions with higher pod yield, whereas cluster V contained accessions with low SLA, high SCMR and moderate pod yield. High yielding as well as stable accessions identified based on AMMI stability value (ASV) are NRCG 17332, 10076, 17268, 17197, 17108, 10106, 10089 and 17165. Trait specific as well as stable accessions identified in the present study can be useful donors for groundnut breeding programme.

Effect of Nutrient Management and Rice Establishment Methods on Groundnut (Arachis hypogaea L.) in Rice–Groundnut Cropping System

The field experiments were conducted at Agronomy Main Research Farm, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India during rabi (November–March) seasons of 2019–2020 and 2020–2021 to evaluate direct and residual effect of nutrient management and rice establishment methods on phenology, growing degree days, growth, yield and economics of groundnut in rice–groundnut cropping system. The experiments were laid out in split-plot design with three replications. Carryover effect of direct seeding rice favourably influenced the succeeding groundnut crop as compared to that grown after transplanting which had superior growth parameters resulting in 25.7% higher pod yield, oil yield (1.24 t ha-1), gross return (` 136612.7 ha-1) and net return (` 63965.0 ha-1). Residual effect of organic management to preceding rice significantly increased growth, yield attributes, growing degree days at physiological maturity and net return, resulted in highest pod yield of 2.48 t ha-1 in groundnut which was at par with that grown after INM in rice, but was on an average, 17.0% higher than inorganic practice in rice. INM to groundnut increased yield parameters and economics of the crop resulting in 19.7 and 39.3% higher pod yields than 100% and 75% soil test based fertiliser, respectively. Hence, INM under direct seeding to kharif rice benefits the succeeding groundnut crop and direct application of 75% STBN (inorganic)+25% STBN (FYM)+0.2 LR+biofertilisers to groundnut proved beneficial for improving phenology, growing degree days, growth, yield and economics of groundnut in rice–groundnut cropping system.

Determination of Kolgrace bio-fertilizer rate for optimum greengram (Vigna radiata L. Wilczek) production in Ibadan, Southwest Nigeria

Greengram productivity has been improved by application of farmyard manures in the last two decades; however, these manures are not readily available as at when needed. In some cases, they are available but in limited supply. Kolgrace bio-fertilizer, a novel commercial product of the Association of Organic Agricultural Practitioners could serve as a superior alternative to farmyard manures. Hence, a field experiment was carried out at the Teaching & Research Farm of the Department of Agronomy, University of Ibadan, Nigeria during the 2015 cropping season to evaluate the effects of five rates (0.00, 0.25, 0.50, 1.00, and 2.00 t ha–1) of Kolgrace bio-fertilizer on the performance of greengram. The aim was to determine the optimum rate of application of this biofertilizer for greengram production. The experimental design was a randomized complete block design with four replications. Data were collected on growth and yield traits, and were subjected to analysis of variance. Results showed that Kolgrace rates significantly (p < 0.01) influenced all the traits measured with exception of fresh pod yield (FPY). Plant height (112 cm), number of leaves (87), stem girth (1.43 mm) and number of flowers (10) at 8 weeks after planting (WAP) were significantly highest with the application of 0.5 t ha–1 whereas, 0.25 t ha–1 gave best results for number of pods (42) and pod yield (3.85 t ha –1). The application of 0.5 t ha–1 is, therefore, recommended if the interest of the farmer is sprout, fodder or green manure, and 0.25 t ha–1 if the interest is for seed production.

Water use pattern and yield response of groundnut (Arachis hypogaea L.) in semi-arid areas of India

Groundnut, an important food legume, is extensively grown in semi-arid regions of India. Water use, water use efficiency and yield response of groundnut grown at three locations, viz., Bellary, Rahuri and Anand during kharif season have been studied for 3 to 5 years. Reduction in pod yield due to moisture stress was found greatest at Rahuri, where a relatively short duration crop was grown in a clayey soil. Total water use was highest at Anand, followed by Bellary and Rahuri. The water use was 660, 460 and 410 mm respectively. At all locations evapotranspiration by the crop was maximal at peg formation to pod development stage of crop growth. The water use efficiency was highest at Bellary followed by Anand and Rahuri. The relative evapotranspiration ratio ETc/ETo for the entire growing season was 0.97, 0.63 and 0.92 at Anand, Bellary and Rahuri respectively. Pod yield showed good correspondence with total water use.

Yield and Disease Responses of Improved Groundnut Genotypes Under Natural Disease Infection in Northern Uganda: Implication for Groundnut Disease Management

Groundnut production in Uganda is constrained by groundnut rosette disease (GRD), the main cause of yield loss experienced by farmers. We conducted the current study to assess the responses of improved groundnuts to diseases (rosette and late leaf spot) and yield under local conditions. Four released groundnut genotypes (Serenut 5R, Serenut 8R, Serenut 9T and Serenut 14R) were evaluated in four locations in northern Uganda for two seasons in 2019. We established the experiment following randomised complete block design with three replications. GRD severity (harvest) and late leaf spot (LLS) severity (harvest) on the four genotypes were not significantly (P &gt; 0.05) different but positively correlated with the Area Under Disease Progress Curve (AUDPC). Genotype-by-location interaction for LLS AUDPC, GRD AUDPC and dry pod yield were significant (P &lt; .001). Season-by-genotype interaction was not significant (P = 0.367). Days to 50% flowering were also not significant (P &gt; 0.05). Highest and lowest yields were recorded for Serenut 9T in the Omoro district (1,291 kg/acre) and the Amuru district (609 kg/acre), respectively. Dry pod yield was significantly (P &lt; 0.001) negatively correlated with GRD severity and GRD AUDPC. Yield performance of the four genotypes was not significantly (P &lt; 0.05) different in the districts, except for Kitgum, where yields of Serenut 9T and Serenut 8R were significantly (P &lt; 0.05) higher. These genotypes could be used to manage GRD by smallholder farmers in Northern Uganda. Special consideration should therefore be given to these four groundnut genotypes for GRD management in the Acholi sub-region.

​Character Association and Path Analysis in Heterotic Recombinant Inbred Lines in Garden Pea (Pisum sativum L.)

Background: Garden pea is one of the principal vegetable crops cultivated in the temperate and sub- tropical areas of the world for its green pods. It is an important food legume worldwide after Phaseolus vulgaris. The knowledge about the interdependence of characters in a particular crop can effectively be employed to breed desirable cultivars and to challenge the consequences of the unprecedented biological, physical and chemical stresses of the future growing conditions. The regression and path analysis further has significance for the assured selection of the varieties with desirable traits and hence adaptation of species in different agro-climatic conditions; hence it is also one of the prerequisites for crop improvement programmes. Correlation and path analysis in garden pea explained that among all the yield contributing traits, number of pods per plant and pod weight have significant contribution in increasing the green pod yield per plant. Methods: 14 heterotic recombinant inbred lines and 17 existing cultivars of garden pea, were put to experimentation for working out the association of the yield and yield contributing component characters under the open field conditions of Regional Horticultural Research and Training Station, Bajaura Kullu, Himachal Pradesh, India. This association was further elaborated through the coefficient of correlation and regression analysis and path coefficient analysis. Result: The genotypic correlation coefficients were found higher than the phenotypic correlation coefficients for all the characters studied. The correlation coefficients revealed that green pod yield per plant had highly significant and positive association with pod weight and number of pods per plant. The path coefficient analysis also revealed that the maximum positive direct effect on green pod yield per plant was exerted by the number of pods per plant, pod weight and 100-seed weight. Through regression equation analysis it became clear that number of pods per plant, pod weight contributed significantly in increasing the green pod yield per plant. With a unit increase in these independent characters, the green pod yield per plant will increase by 2.34 and 33.45 per cent. It can thus be concluded that despite of the positive correlation of almost all the characters with green pod yield per plant, only number of pods per plant and pod weight are important and significant independent characters for increasing the green pod yield per plant.

Enhancing Uptake of K and Zn and Improving Yield of Groundnut by Application of K- and Zn- Solubilizing Bacteria

Background: Potassium and zinc are important with respect to mineral nutrition of groundnut and play a significant role in physiological and biochemical processes and thus affect productivity. To make these important minerals available to the growing plants in calcareous soil having fixation problem, the current investigation was undertaken to identify both K- and Zn-solubilizing bacteria for improving growth, nutrient uptake and yield of groundnut. Methods: Soil samples were collected from groundnut rhizosphere during 2018 for the isolation of Zn- and K- solubilizing bacteria. Estimation for Zn- and K-solubilization was done using zinc phosphate and potassium aluminosilicate as insoluble form of Zn and K, respectively. Promising Zn and K solubilizing bacterial isolates were selected and evaluated in pots. Result: Inoculation of different isolates of KSB and ZSB improved K and Zn contents of shoot and seed during summer and kharif 2019. Evaluation of KSB and ZSB isolates, in potted condition, resulted in improved pod yield upto 39.6% (KSB) and upto 37.1% (ZSB) during summer and upto 24.1% and 25.1% during kharif 2019, respectively. Therefore, uptake of Zn- and K- and yield of groundnut can be enhanced significantly by application of both potential ZSB and KSB.

​Management of Early Leaf Spot (Cercospora arachidicola) of Groundnut in Rajasthan

Background: Early leaf spot caused by Cercospora arachidicola Hori. is most destructive disease in all the groundnut growing areas of Rajasthan, under severe infestation it cause 30-50% losses in pod yield. Recently, Central Insecticide Board (CIB), Faridabade banned 27 pesticides including some important fungicides which are extensively used in plant disease management. Therefore, in the present investigation, our main emphasis was to find out some new fungicides for management of early leaf spot disease. Methods: Ten fungicides (hexaconazole 5% EC, difenconazole 25% EC, propiconazole 25% EC, tebuconazole 25.9% EC, trifloxystrobin 25% + tebuconazole 50% WG, mancozeb 50% WP, chlorothalonil 75% WP, carbendazim 50% WP, carbendazim 12% + mancozeb 63% WP and captan 70% + hexaconazole 5% WP) were evaluated against early leaf spot pathogen (C. arachidicola) both in lab as well as in field condition. The experiment was conducted at ARS, SKRAU, Bikaner during Kharif-2019 on most popular cv. HNG-69 in RBD design with the application of foliar spray of ten different fungicides at different concentrations against early leaf spot disease and compared with an untreated control. Result: Among all the fungicides used in the present investigation, Tebuconazole 25.9% EC was found most effective in inhibiting the mycelial growth of the pathogen followed by trifloxystrobin 25% + tebuconazole 50% WG. Under field condition, it gave maximum (70.73%) disease control with highest pod yield (31.5 q/ha) and net return (Rs 57,500/ha) when applied as foliar spray at 0.1% concentration followed by trifloxystrobin 25% + tebuconazole 50% WG at 0.2%. These treatments can provide an effective and economical management of early leaf spot disease for groundnut cultivators.

Use of PNUTGRO model for optimization of sowing date and plant spacing to maximize yield of groundnut (Arachis hypogaea L.)

Lkkj & ihuVxzks ¼ih- ,u- ;w- Vh- th- vkj- vks-½ ekWMy dh izkekf.kdrk fl) djus ds fy, 1987 - 90 ds nkSjku vkuan] xqtjkr esa {ks=h; iz;ksx fd, x, gSaA bl ekWMy dk mi;ksx ew¡xQyh dh QhuksykWth] c<+ksrjh] fodkl vkSj iSnkokj dk iwokZuqeku yxkus ds fy, fd;k x;k gSSA ew¡xQyh ds izfr:fir iq"iu] isfxax] Qyh cuus vkSj Qyh idus dh frfFk;ksa] i.khZ {ks=Qy lwpdkad ¼,y- ,- vkbZ-½ tSoHkkj] 'kSfyax dk izfr’kr rFkk iSnkokj dh rqyuk rhu i)fr;ksa uker% th- ,- ;w- th- 10] th- ,- ;w- th- 2 vkSj vkj- vk-sa - 33 - 1 ls izkIr gq, iszf{kr ekuksa ds lkFk dh xbZ gSA izfr:fir ?kVukØe ls iq"iu ds fy, ,d fnu deh rFkk ik¡p fnu dh c<+r dk] isfxxa ds fy, 2 ls 6 fnuksa dh c<+r] Qyh cuus ds fy, 3 fnu dh deh rFkk 6 fnuksa dh c<+r dk vkSj Qyh idus ds fy, 6 fnu dh deh rFkk 5 fnu rd dh c<+r dk varj ik;k x;k gSA okLrfod ekuksa dh rqyuk esa bl ekWMy ls i.khZ {ks=Qy lwpdkad 91-8 ls 105-8 izfr’kr vkSj 'kSfyax dk izfr’kr 81-5 ls 109-8 ik;k x;k gSA bl ekWMy ls ew¡xQyh dh iSnkokj izsf{kr ekuksa dh rqyuk esa 88-5 ls 112-7 izfr’kr rd ikbZ xbZ gSA bl ekWMy ls izkIr ifj.kkeksa ds vk/kkj ij ij yxkrkj pkj Qlyksa vkSj _rqvksa ds laca/k esa ew¡xQyh dh QhuksYkWkth] c<+ksrjh] fodkl vkSj iSnkokj ds ckjs esa iwokZuqeku larks"ktud ik;k x;k gSA ew¡xQyh dh izsf{kr vkSj izfr:fir iSnkokj ds chp 11 izfr’kr dh ?kVc<+ ikbZ xbZ gS ftlls irk pyrk gS fd ekWMy ds vk/kkj ij fd;k x;k iwokZuqeku larks"ktud gSA ,y- ,- vkbZ- dks NksMdj okLrfod ekuksa vkSj izsf{kr ekuksa esa varj ¼Mh-½ 0-03 vkSj 1-77 ds chp jgk gS ftlls ekWMy ds larks"ktud dk;Z djus dk irk pyrk gSA izfr:i.k v/;;uksa ds ifj.kkeksa ls irk pyrk gS fd tc vf/kd o"kkZ gksus dhs laHkkouk gks rks ew¡xQyh ds chtksa dh lkekU; nwjh rFkk cqokbZ ds lkekU; le; dh vis{kk chtksa dks vf/kd ikl&ikl cksdj rFkk cqokbZ yxHkx ,d lIrkg igys djds ew¡xQyh dh vf/kd iSnkokj izkIr dh tk ldrh gSA Field experiments were conducted at Anand, Gujarat during 1987-90 to validate the PNUTGRO model. The model was used to predict phenology, growth, development and yield of groundnut. The simulated flowering, pegging, pod formation and pod maturity dates, leaf area index (LAI), biomass, shelling % and pod yield of groundnut were compared with the observed values for three cultivars viz., GAUG 10, GAUG 2 and Ro-33-1. The simulated phenological events showed a deviation of –1 to +5 days for flowering, +2 to +6 days for peg formation, -3 to +6 days for pod formation and –6 to +5 days for pod maturity of the crop. The model estimated leaf area index within 91.8 to 105.8% and shelling percentage within 81.5 to 109.8% of the actual values. The model simulated the pod yields within 88.5 to 112.7% of the observed values. The results obtained with the model for the four consecutive crops and seasons revealed satisfactory prediction of phenology, growth, development and yield of groundnut. The percent error between observed and simulated pod yield was 11% which indicated satisfactory prediction by the model. The degree of agreement (d) ranged between 0.03 and 1.77 except for LAI indicating satisfactory performance of the model. Results of simulation studies indicated that when there is a possibility of high rainfall higher pod yield can be achieved by adopting closer spacing and early sowing (one week earlier than normal date of sowing) compared to normal spacing and date of sowing.

Assessment of the genetic diversity and population structure of groundnut germplasm collections using phenotypic traits and SNP markers: Implications for drought tolerance breeding

Profiling the genetic composition and relationships among groundnut germplasm collections is essential for the breeding of new cultivars. The objectives of this study were to assess the genetic diversity and population structure among 100 improved groundnut genotypes using agronomic traits and high-density single nucleotide polymorphism (SNP) markers. The genotypes were evaluated for agronomic traits and drought tolerance at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT)/India across two seasons. Ninety-nine of the test genotypes were profiled with 16363 SNP markers. Pod yield per plant (PY), seed yield per plant (SY), and harvest index (HI) were significantly (p < 0.05) affected by genotype × environment interaction effects. Genotypes ICGV 07222, ICGV 06040, ICGV 01260, ICGV 15083, ICGV 10143, ICGV 03042, ICGV 06039, ICGV 14001, ICGV 11380, and ICGV 13200 ranked top in terms of pod yield under both drought-stressed and optimum conditions. PY exhibited a significant (p ≤ 0.05) correlation with SY, HI, and total biomass (TBM) under both test conditions. Based on the principal component (PC) analysis, PY, SY, HSW, shelling percentage (SHP), and HI were allocated in PC 1 and contributed to the maximum variability for yield under the two water regimes. Hence, selecting these traits could be successful for screening groundnut genotypes under drought-stressed and optimum conditions. The model-based population structure analysis grouped the studied genotypes into three sub-populations. Dendrogram for phenotypic and genotypic also grouped the studied 99 genotypes into three heterogeneous clusters. Analysis of molecular variance revealed that 98% of the total genetic variation was attributed to individuals, while only 2% of the total variance was due to variation among the subspecies. The genetic distance between the Spanish bunch and Virginia bunch types ranged from 0.11 to 0.52. The genotypes ICGV 13189, ICGV 95111, ICGV 14421, and ICGV 171007 were selected for further breeding based on their wide genetic divergence. Data presented in this study will guide groundnut cultivar development emphasizing economic traits and adaptation to water-limited agro-ecologies, including in Ethiopia.