The aim of this study is to investigate growth and yield response of groundnutgenotypes as influenced by nitrogen fertilizer and irrigation.
To evaluate yield and its quality, ten groundnutgenotypes subjected to the influence of two irrigation levels and two different doses of Nitrogen, in a field experiment was conducted at Tamburesti Research Station, of University of Craiova, Romania, during 2014-2017, located at latitude of 44°1'40'' N, longitude 23°56'9'' E. The sandy soil contains 6-8% physical clay. The depth of the phreatic water is approximately at 7m from the surface of dunes. The difference of the levels between dunes and interdunes varies between 2- m. The quantity of humus is low (0.3- 0.5% at the sand of dune and 0.6-1.2 at the sand of interdune). The reaction of these sands varies from weak acid till neutral (D.H. = 6.3-7.1), while the total capacity of cation exchange is reduced (3-5m is at 100/g soil in the dune and 5-7m is at 100/g soil at interdune). The sands are very poor in nitrogen and phosphor and mediocre supplied with potassium (0.03-0.05% total nitrogen; 2-5 mg/100 g soil phosphor assimilable and approximately 12 mg/100g soil assimilable potassium) (sand analysis made in Chemistry Laboratory of Faculty of Agronomy). The experiment was carried out during 2014-2017 and sowed in randomized block design with three replicates. It included three factors: two levels of irrigation (a 1 – non - irrigated and a 2 - irrigated), two levels of fertilization (b 1 – non-fertilized and b 2 - 100 active Nitrogen/ha) and genotype (C 1 -C 10 ). Data were statistically analyzed and means were compared by least significant differences (LSD), P=0.05.
Drought is one of the major abiotic stresses that seriously decrease crop productivity in arid and semi-arid regions of the world (Yang et al., 2010; Lipiec et al., 2013). A fast screening tool would be helpful in selecting valuable genotypes with defined growth strategies those confines to droughttolerance suitable for breeding programmes. Seed germination and early seedling growth are critical stages for plant establishment (Li et al., 2011), and are more sensitive to drought stress during the seedling stages. Screening drought-resistant plant genotypes is a fundamental goal targeted in arid and semi-arid regions. Nonetheless, drought cannot be easily controlled in the field because of rainfall that can impede water deficit (Muscoloa et al., 2014). It is necessary to alleviate the adverse effects of drought stress for achieving good crop yields (Ashraf and Rauf, 2001). Therefore, assessing plant response to drought at early seedling stage was commonly achieved using chemical desiccators such as polyethylene glycol (PEG). Several reports have shown that in vitro screening technique using PEG is one of the dependable approaches for the selection of desirable genotypes to study in detail on water scarcity on plant germination indices (Landjeva et al., 2008; Almaghrabi, 2012; Ahmad et al., 2013; Jatoi et al., 2014). The upsurge in concentration of PEG caused decrease in germination percentage, seedling vigour in certain crop plants (Khodarahmpour, 2011). One of the important findings is that a positive correlation between droughttolerance of the genotypes in the field and in laboratory experiments was noted (Kosturkova et al., 2014). Therefore the current study was planned to assess genetic diversity among eight groundnutgenotypes using RAPD markers and to find out appropriate criteria for simple and quick screening of genotypes that have higher tolerance to drought in support of breeder’s crop improvement programs.
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Received: August 7, 2014/ Accepted: October 27, 2014
Groundnut is the most important pulse crop in East Nusa Tenggara (ENT); however, the crop yield in ENT is low due to erratic climatic condition, drought stress, and low yielding ability of most cultivated genotypes. Local Rote is a well-known local groundnut variety in ENT, which is a potential superior variety and parental source due its large seed size and high yielding ability. Information on its resistance to abiotic and biotic stresses is important for its future development. Five groundnutgenotypes, Local Rote and check varieties were elucidated to identify drought resistant genotypes. The study was carried out in a split-plot design with three replicates in two locations during dry season 2013. Two irrigation regimes (optimum and stress conditions) were assigned as main plot and 5 groundnut geno- types as sub-plot. Research results revealed significant effect of irrigation by genotype interaction on observed yield and yield compo- nent characters in both locations. Seed yields of most tested genotypes were below their yield potential. Local Rote yielded best over two locations (1.26 t.ha -1 seed yield). Yields of check varieties were below 1.0 t.ha -1 . Local Rote was considered tolerant to drought based on STI, GMP, SSI and YL selection indices.
On the other hand, a major problem of cropping systems is the reduction in soil productivity that accompanies most systems of continuous cultivation, while intercropping usually includes a legume which fixes nitrogen, and which may confer some benefits to the system, because the cereal component depends heavily on nitrogen for maximum yield (Ofori and Stern, 1986). Moynihan et al. (1996) mentioned that intercropping annual legumes with grain crops has been proposed as a cropping strategy to enhance ground cover, thereby reducing weed competition, suppressing soil erosion, and providing N for use by subsequent crops. So, with such systems synthetic N-fertilizer and herbicide use might be reduced. Millet, when intercropped either with cereals or legumes, used water more efficiently for grain production (Oluwasemire et al., 2002). Legumes are particularly attractive as components of grain cropping systems because of their ability to fix N and serve as a green manure with a low C: N ratio (Sims and Slinkard, 1991).
Seventy groundnutgenotypes were evaluated for quantitative and yield parameters. A wide range of variation was observed for important yield components. High estimates of the genotypic coefficient of variation (GCV) were observed for kernel yield per plant followed by the number of branches per plant, harvest index and biological yield per plant. The estimates of heritability were observed to be high for harvest index followed by biological yield per plant, kernel yield per plant, 100-kernel weight, plant height, 100-pod weight and number of branches per plant indicated that these characters were less influenced by the environmental fluctuations. High heritability along with high genetic advance was observed for 100-pod weight. High heritability along with moderate genetic advance was observed for biological yield per plant, 100- kernel weight and harvest index indicating that these traits were mainly governed by additive gene action and responsive for further improvement of these traits.
and subsequent chromosome doubling. Based on the patterns of reproductive and vegetative branching and on the pod morphology, the cultivated species is divided into two cultivated subspecies that is A. hypogaea subsp. hypogaea and A. hypogaea subsp. fastigiata. The subspecies are further divided into botanical varieties. The subsp. hypogaea is divided into hypogaea (virginia) and hirsuta, while the subsp. fastigiata is divided into fastigiata (valencia), vulgaris (Spanish), peruviana and aequatoriana (Krapovickas & Gregory, 1994). Groundnut is grown in more than 100 countries covering over 26 million (M) hectares (ha) area in 2014 with a global production of about 44 M metric tons and an average yield of about 1,655 kg /ha (FAOSTAT 2017). Asia (58.3%) and Africa (31.6%) accounted for about 90% of the world 's production with China (16.6 M tons), India (6.6 M tons) and Nigeria (3.4 M tons) being the top three largest producing countries (FAOSTAT, 2017). The groundnut seed contains 22% to 30% protein and 35% to 60% oil and is a rich source of diet- ary fibre, minerals, vitamins and bioactive compounds, hence con- tributing to household nutrition. It is suitable for making nutrient ‐ dense foods for alleviating malnutrition in vulnerable groups such as pregnant and breastfeeding women and children under 2 years, par- ticularly in developing countries (Anim ‐Somuah, Henson, Humphrey, & Robinson, 2013). The haulms and groundnut cake are important sources of animal feed. In addition, groundnut has the ability to fix atmospheric nitrogen benefitting the succeeding crop. As a cash crop, it is frequently traded locally, regionally and globally, signifi- cantly contributing to rural household cash income and national economy. In the west and central Africa (WCA), for example, groundnut accounts for up to 50% or more of rural household cash income in many countries —46% in Mali, 54% in Nigeria, 66% in Niger and 80% in Senegal (GAIN 2010; Ndjeunga et al., 2010). In Asia and Africa, a large number of women and youth are engaged in the cultivation, processing and marketing of groundnut, thereby con- tributing to their economic participation and empowerment. In Nige- ria, for example, almost all the small ‐scale groundnut oil processing is controlled by women. In Mali, about 85% of groundnut fields are owned by women (Ndjeunga et al., 2010).
important oilseed crop of India. It is also cultivated worldwide. It is a rich source of edible oil, high quality protein, fat and carbohydrates. In India groundnut crop is cultivated on area of 46.6 lakh hectares and production of 78.1 lakh tones with productivity of 1712 kg ha -1 during the year 2013- 14, while in Maharashtra state it is cultivated on area of 1.96 lakh hectares with productivity of 1163 kg ha -1 and production of 2.28 lakh tones during kharif season and 0.71 lakh ha area and 0.97 lakh tonnes production with 1366 kg ha -1 productivity during rabi season 2013-14. In Konkan region groundnut crop is cultivated on more than 12700 ha area with productivity of 841 kg ha -1 and 2117 kg ha -1 during Kharif and Rabi respectively. In respect of varying environmental conditions and soil types, there are specific genotypes suited for specific regions. It is not possible to have one common cultivar to suit different regions. It is therefore, required to improve the region specific cultivars with high dry pod yields and adaptations. Exploitation of hybrid vigour in crop plants for quantum jump in yield and other quantitative characters is one of the approaches in crop improvement to cope up with the ever-increasing demand for food grains and oil production. In groundnut, heterosis cannot be exploited for higher production through commercial hybrids due to cleistogamous nature of flower and poor seed recovery during hybridization. For the development of an effective heterosis breeding programme in groundnut, one need to have information about genetic architecture and estimated prepotency of parents in hybrid combinations. The information is also
Developmental stage effects
An examination of mean values of different gener- ations in each cross showed that phenotypic values of
SCMR and SLA differed significantly at two devel- opmental stages, except for SLA in ICG 9418, SCMR and SLA in Chico, and SLA in F1 and BC1P2 of the cross ICG 6766 9 Chico (Table 2 ). The mean of SLA in all the generations decreased significantly when measured at 80 DAS except in the cases where there were no significant differences while SCMR increased significantly as compared to means observed at 60 DAS. The mean SCMR and SLA of Chico did not differ across the stages of measure- ment. However, ICG 7243 and ICG 6766 showed higher value of SCMR and reduced value of SLA at 80 DAS as compared with 60 DAS. This trend was observed across the generations in both the crosses. However, the pattern was almost same at both the stages. This shows that SCMR and SLA should be recorded between 60 and 80 DAS for screening the germplasm lines for droughttolerance. This period corresponds with the pod filling stage which is most sensitive to drought in groundnut (Nageswara Rao et al. 1985 , 1993 ).
raised in a randomized block design and evaluated with three replications. Individual cross combinations along with their parents were raised in four meter row with a spacing of 30 x 10 cm. The package of practices recommended for the groundnut cultivation was followed for all the entries throughout the crop growing period.
Groundnut has a narrow genetic base as a result of its monophyletic origin, self- pollination and lack of gene flow, due to origin of the crop through a single hybridization event between two diploid species followed by a chromosome doubling and crossing barriers with wild diploid species (due to ploidy differences). Moreover, to improve and sustain the yield of groundnut, plant breeders should have a better understanding of the genetic variability of yield and its components and development of high yielding cultivars with resistance to aflatoxin contamination (Zaman et al., 2010). Climate change and global warming is bringing about genetic erosion. There is therefore a need to study the genetic variability of plants for the efficient management and the conservation of races and their optimum utilization in plant breeding. Genetic variability is essential for initiating an effective and successful breeding programs thus it is imperative to study the level of genetic variability available in the existing genotype. The studies of heritability estimates with genetic advance further clarify the nature of characters which can be improved through selection. Several studies on groundnut have been carried out, however, there is limited information regarding its genetics, breeding and production, especially genetic improvement under rain fed conditions in Ethiopia. That is why the present study has been designed to study genetic variability parameters in groundnutgenotypes grown in Ethiopia.
Analysis of variance revealed that highly significant differences among the genotypes were observed for all the traits. Which indicating the presence of good amount of genetic variability among the material studied. The genotypic correlations were higher than the phenotypic correlation for most of the character studied that indicating least environmental effects on the expression of the traits (Table 1). In the present study, pod yield per plant was found to be significantly and positively correlated with number of mature pods per plant, 100- pod weight, 100-kernel weight, sound mature kernels, shelling out-turn, biological yield per plant, harvest index, kernel yield per plant, and protein content at genotypic and phenotypic levels. Such positive interrelationship between pod yield per plant and these attributes has also been reported in groundnut by several researchers.
The comprehensive QTL analysis detected 153 main effect QTLs (M- QTLs) and 25 epistatic QTLs (E-QTLs) for droughttolerance related traits. Localization of these QTLs revealed 16 genomic regions that contained 125 QTLs in the consensus map. Importantly, no major single QTL for droughttolerance was detected. Therefore, novel breeding approaches like MARS (marker-assisted recurrent selection) and GWS (genome wide selection) are more likely to be required for the introgression of a larger number of QTLs in order to develop drought tolerant groundnutgenotypes. As a final objective, an international reference consensus genetic map using the marker segregation data for 10 RILs and one BC population from the international groundnut community has been constructed. This consensus genetic map is composed of 897 marker loci, distributed on 20 linkage groups (a1–a10 and b1–b10) and covering a genetic distance of 3864 cM. The highest numbers of markers (70) were located on linkage group ‘a1’ and the least number of markers (21) on ‘b9’. The marker density was lowest (6.4 cM) on ‘a8’ and highest (2.5 cM) on ‘a1’. The reference consensus genetic map has been divided into 203 BINs, each of 20 cM. PIC (polymorphism information content) value was provided for a total of 526 markers in 190 BINs.
Oil content is of primary importance in groundnut, and in Indian cultivated groundnut varieties it ranges from 47 to 54.6% (Bishi et al., 2013). Likewise, the protein content in groundnut kernels varies from 22-36% depending on cultivar, location, season, seed maturity and agronomic practices. Average protein content is higher than that of eggs, dairy products, meat and fish and the digestibility of groundnut protein is very high (Singh and Singh, 1991). The soluble sugars content in groundnut varies from 9.2 to 13.3% (Asibuo et al., 2008)These three biochemical components have greater dietary importance, and groundnut is of much relevance particularly in vegetarian diet. However, except oil content to some extent, the work to improve these biochemical components through breeding is limited in groundnut. Information on the genetic control of these traits is important for initiating a breeding programme. Therefore, the present investigation was taken up to study the genetic nature of oil, protein and total soluble sugar content in groundnut.
The genotype ICG-8434, TAG-24 and ICG-8496 (1.18 g) recorded minimum and genotype TPG-41 (1.84 g) recorded maximum dry matter of roots plant -1 (Table 3). Ghosh et al. (1997) stated that, there was negligible amount of dry matter partitioning into the roots. In spite of roots, the rate of dry matter production in stem was higher. The genotypes ICG-8354 (10.29 g), ICG-8428 (10.12 g) and ICG 8519 (9.97 g) exhibited higher dry matter partitioning plant -1 in stem.TPG-1 (11.63 g plant -1 ), TAG-24 (1154 g plant -1 ), ICG-8437 (11.28 g plant -1 ) and ICG- 8519 (11.24 g plant -1 ) recorded maximum dry matter accumulation in leaves. The above findings were in agreement with the results of Kumar and Kumar (1999). After the flowering dry matter was shared in reproductive parts. The total dry matter accumulation in vegetative parts get declined and increased in reproductive parts. The total dry matter accumulation increased in the pods with advancement of crop growth stage. These findings are in conformation with findings of Murthy et al. (2002). The genotypes ICG-8029 (19.24 g), ICG-8468 (17.83 g) and ICG-8444 (17.59 g) recorded highest dry matter of pods plant -1 at harvest. ICG-8029 (0.327 g/day), ICG-8542 (0.314 g/day) and TAG-24 (0.311 g/day) had higher daily rate dry matter efficiency. Amongst these, even though the genotype ICG-8029 had higher daily rate of dry matter efficiency recorded less amount of relative dry matter efficiency (39.9%), whereas, ICG-8542 (42.7%) and TAG-24 (42.7%) maintained higher percent of relative dry matter efficiency.
Ys had positive and significant correlation with MP, STI, and GMP. These results may advise MP, STI and GMP to bethe best predicates for both conditions. SSI, TOL and YSI showed disparity against Ys and Ypindicating the population segregated for genes conditioning yield potential and low Ntolerance. These result was in line withAli and El-Sadek (2016), Talebi et al. (2009),Mohammadi et al. (2012), Ganjeali et al. (2011) and Sio-Se Mardeh et al. (2006).Majidi et al. (2011) reported that GMP and STI indices were similarly able to separate drought sensitive and tolerant genotypes of safflower in both mild and intense water stress environments. Pireivatlou et al. (2010) was also notedthat STI it self can be a reliable index for selecting high yielding genotypes.
5.0 kg ha -1 , had no deleterious effect on Azospirillum sp. A similar individual instigate effect of monocrotophos and chlorpyrifos was previously demonstrated on the population of Azospirillum sp. . Similarly, observations with other organophosphorus and pyrethroid insecticides and fungicides have also been reported [44,41]. Interactions between different agrochemicals applied in repeated application on microorganisms and their activities in soils have received little attention in comparison to effects of a single agrochemical. There were no differences in degree of diversity in bacterial populations from the application of a combination of five pesticides, including chlorfenviphos and glyphosate, to field plot of 20 years . In the present study the application of pesticides to the soils at certain concentrations was not harmful to the population of Azospirillum sp. Some reports have been published on interactions between pesticides and their solvents, pesticides and their degradation products, and two different pesticides on growth of organisms in pure culture studies of fungi, algae and cyanobacteria [55,56,57,58,59,60,61]. In all these studies, a variety of interaction effects such as synergistic, additive and antagonistic were observed, depending on concentration of the interacting chemicals. For instance, the combination of permethrin and its degradation product interact to yield antagonistic, additive and synergistic interactions towards the growth of fungi in pure culture , because the degradation rate of an
cakes are used as industrial raw material and fertilizer (Ayele, 2010). These multiple uses of groundnut plant makes it an excellent cash crop for domestic markets as well as for foreign trade in several developing and developed countries (Ephrem, 2015). According to Trawalley (1998), its protein content is the cheapest source of dietary protein in places where meat is scarce and very expensive for large proportion of subsistent farming communities. The hay (vine) is a nutritious animal feed, particularly for the subsequent dry season when green forage is not available (Naab et al., 2005). In addition, groundnut seed and hay are often sold in local markets, providing income to resource-poor farmers (Naab et al., 2005; Nutsugah et al., 2007). Groundnut is affected by several diseases, such as early leaf spot (Cercospora arachidicola S. Hori), late leaf spot (Phaeoisariopsis personatum Berk. and Curt.), collar rot (Aspergillus niger), rust (Puccinia arachidis Speg), and bud necrosis (bud necrosis virus (BNV) (Ephrem, 2015). Early leaf spot (caused by Cercospora arachidicola S. Hori) and Late Leaf Spot (caused by Cercosporidium personatum) are most devastating and economically important foliar fungal diseases and major yield reducing factor of groundnut worldwide (Backman and Crawford, 1984; Khaleque, 1985, Smith et al., 1992 and Mirza, 1998). Leaf spots of groundnut are one of the most important diseases of this crop worldwide with annual yield losses of 15 to 50% (Lucas et al., 1992). Most farmers control these diseases using fungicides. However, the negative environmental impacts, mammalian toxicity and high costs are making their usage unattractive thereby searching for alternatives such as natural plant-based chemicals (Asawalam, 2006). Plants have ability to synthesize aromatic secondary metabolites, like phenols, phenolic acids, quinones, flavones, flavonoids, flavonols, tannins and coumarins (Cowan, 1991). These groups of compounds show antimicrobial effect and serves as plant defense mechanisms against pathogenic microorganisms (Das et al., 2010). Many research workers have tried to find out safe and economical control of plant diseases by using extracts of different plant parts (Hasan et al., 2005; Bdliya and Alkali, 2008). The use of plant extracts with antifungal activity offers an economical, safe, and easily available alternative method for the management of leaf spot disease of groundnut (Rahman and Hossain, 1996). Hence the objective of the study was to evaluate and determine the efficacy of plant extracts on mycelial growth and sporulation density of fungal pathogens in-vitro
Application of discriminant function as a basis for making selection on several characters simultaneously is aimed at discriminating the desirable genotypes from undesirable ones on the basis of their phenotypic performance. A model suggested by Robinson et al. (1951) was used for the construction of selection indices and the development of a required discriminant function. For the construction of selection indices, the characters, which had desirable correlation as well as moderate to high direct effect on pod yield per plant, were considered. In this context, the pod yield per plant (X 1 ) along with its five components