Evaluation of pigeonpea (Cajanus cajan) genotypes against pigeonpea sterility mosaic disease.

Abstract

Pigeonpea (Cajanus cajan) is a drought-resistant pulse crop cultivated in the semi-arid regions of the world. Sterility mosaic disease (SMD) also known as “green plague of pigeonpea” is one of the severe threats in pigeonpea production causing severe yield loss. To overcome this issue, breeding for resistant varieties is considered to be one of the most effective and economic methods of reducing the crop losses and has received the top priority. Ninety four genotypes including checks were screened for SMD resistance by adopting leaf stapling technique at glass house condition. Based on the percent disease incidence (PDI), the genotypes could be classified as highly resistant (0%) and highly susceptible (100%). out of ninety four genotypes screened , four genotypes i.e., DPP 2-89, DPP 3-182, IC 22557 and ICP 3666 showed highly resistant reaction to SMD infection while fifty four genotypes were highly susceptible. Therefore, these four genotypes may be utilized for SMD resistance breeding programme. Introduction Pigeonpea (Cajanus cajan) is one of the most important pulse crops of semi-arid tropics and subtropics regions viz., Asia and Africa (Van Der Maesen, 1990). Pigeonpea also popularly known as redgram, tur or arharand is primarily grown for its protein source particularly in the developing countries like India, where majority of the population depends on low priced vegetarian foods for meeting their dietary requirements. Pigeonpea seed contains rich source of essential amino acids, carbohydrates, minerals and high amounts of vitamin A and C (Faris, 1987) and is the principal source of dietary protein (20 to 30 %) for an estimated population of 1.1 billion. It is grown as a sole crop or as an intercrop with cereals (maize, sorghum, pearl millet, finger millet), fibre and other legume crops (groundnut, soybean) under wide climatic conditions and rainfed lowinput agricultural systems (Nene and Sheila, 1990). India stands first in both area and production of pigeonpea among the countries. However, its productivity is lower than the world average, which may be attributed to various abiotic and biotic constraints. The major biotic stresses are Sterility Mosaic Disease(SMD) and Fusarium wilt which causes severe economic yield loss. Sterility Mosaic Disease is one among the most destructive diseases. The causal agent of the disease is Pigeonpea Sterility Mosaic Virus and is transmitted by the vector, Eriophyid mite (Aceria cajani).The symptom of SMD includes bushy and pale green leaves, excess vegetative growth, leaf size reduction, mosaic and mottling of leaves and cessation of reproductive structures. The disease also described as the green plague because at flowering time, affected plants remain green with more vegetative growth and have no flower, and spread rapidly like a plague, leading to severe epidemics. The infected plants fail to produce flowers and therefore no pod set occurs causing severe yield loss. Even though control of disease by chemicals is effective but it is not economically viable and non eco-friendly (Nene et al., 1990). Breeding for SMD resistant pigeonpea genotype is regarded as one of the most effective and economic methods to increase the yield. Hence, the present study was aimed at identifying genotype with stable and broad based resistant to SMD. Materials and Methods The present investigation on intensive screening of pigeonpea genotypes against sterility mosaic disease was carried out during Kharif 2018 under Glass house condition in Department of Pulses, Tamil Nadu Agricultural University, Coimbatore. Ninety four pigeonpea germplasm was evaluated for sterility mosaic disease screening. The susceptible pigeonpea variety, ICP 8863(Maruthi) was used as inoculum which is maintained in the Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore. Leaf stapling technique (Nene and Reddy 1976a)was adopted to transmit the disease. The SMD infected leaf samples were collected and observed under binocular microscope for the presence of Eriophyid mites (Aceria cajani), which transmits the SMD causing virus. Then, the leaf samples were stapled in the primary leaves of genotypes to be screened. Plants were scored for SMD incidence at 15 days interval from day after the first inoculation up to 90 days by observing the Electronic Journal of Plant Breeding, 10 (2): 727-731 (Jun 2019) ISSN 0975-928X 728 DOI: 10.5958/0975-928X.2019.00094.2 disease symptom. Based on the disease development the PDI was calculated and the genotypes were grouped. Based on the disease reaction, genotypes were categorized as resistant, moderately resistant, susceptible and highly susceptible. Results and Discussion Among ninety four genotypes screened for their resistance to SMD five genotypes viz., DPP 2-89, DPP 3-182, IC 22557, ICP 3666 and ICP 13264 showed highly resistant reaction with 0% PDI and three genotypes viz.,IC 525411 (8%), ICP 12327 (5%) and ICP 14040 (5%) were found to be resistant genotypes. The genotypes viz., ICPL 11023, IC 525413, IC 525424, ICP 12467, ICP 12527, C2542, ICP 3359, ICP 10242, ICP 10760, IC 332216 and CO 8 were identified as moderately resistant with the range of 12 – 25 per cent disease incidence and twenty one genotypes showed susceptible reaction with the range from 34.67 50 per cent disease incidence. Fifty three genotypes showed highly susceptible reaction with range from 52 -100 per cent disease incidence. The results are presented in the Table 1. By using the leaf stapling technique Prabhavathi and Ramappa (2018) reported that out of sixty one genotypes, ICPL 99095 and ICP 7035 showed resistant reaction and ICPL 20123 showed moderately resistant reaction and remaining entries showed susceptible reaction. Joshi et al. (2017)found that thirty three RILs were identified as resistant lines which consistently showed 0% PDI during screening. On Screening of 60 entries, only eight entries viz.,ICPL87119,ICPL-2376,BDN-2,PT-4-307,CORG9701,BSMR-736,GRG-811and BSMR-853 were found resistant to be sterility mosaic disease, as reported by Vijaya Bhaskar (2016).Similarly eighteen genotypes were found to be highly resistant against sterility mosaic which has been reported by Kaushik et al. (2013). Among 146 accessions six accessions and 24 accessions showed resistant reaction to Fusarium Wilt and SMD, respectively. Combined resistance to Fusarium wilt and SMD was found in five accessions, ICP 6739, ICP 8860, ICP 11015, ICP 13304 and ICP 14819 as been reported by Sharma et al. (2012).Manjunatha et al. (2013)evaluated pigeonpea genotypes against SMD during 2010-11 and 2011-12 by leaf stapling technique and found that seven entries viz., ICP 7035, BRG 3, ICPL 87091, IPA 8F, IPA 15-F, GT 101 and JKM 189 were resistant. Similar result has been reported by Pallavi (2014) using leaf stapling technique to screen the pigeonpea genotypes against sterility mosaic disease and found that five genotypes viz., ICP 7035, GAUT001, BAHAR, BRG-3, and IPA 8F showed resistance, eight genotypes showed moderately resistance and 261 genotypes showed susceptible reaction. Jaggal et al. (2014)reported that out of 135 Pigeonpea accessions evaluated for FW and SMD,24 accessions were found to be resistant for both FW and SMD under field condition. The biometrical characters were tabulated for highly resistant, resistant and moderately resistant lines in Table 2. The highest mean performance for pod weight per plant and single plant yield was recorded in IC 525413 with the value of 185.67g and 99.13 g, respectively, whereas CO 8 (4.45 and 376.25) recorded highest mean value for number of seeds per pod and number of pods per plant, respectively. Genotype IC 332216 (13.07) recorded high mean value for hundred seed weight. The highest mean performance for Shelling percentage was exhibited by ICP 3359 (84.12 %). Based on the screening and yield performance data the genotype IC 525413 showed moderately resistant reaction to SMD with high single plant yield. Hence, this genotype may be used as parent for SMD resistant breeding programme. Highly resistant lines with low yield performance may also be used as donor parent for introgression of resistance to high yielding varieties.