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M. RESHAD ABDULRAHIMZAI*, N.C. VENKATESWARLU, K.V. HARI PRASAD and G . MOHAN NAIDU
Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati – 517502, Chittor Dt., A.P., India
A field experiment was conducted to screen the blackgram genotypes at dry land farm, S.V. Agricultural College,Tirupati during rabi2018-19 for identification of resistance source for utilization in developing the resistant varieties of blackgram. Total 20 genotypes along with two susceptible checks viz., TBG-140 and LBG-645 were screed for Leaf Curl and Yellow Mosaic Virus (YMV). The results revealed that PU-31 genotype recorded lowest incidence of leaf curl followed by GBG-1 and found resistant with 1 scale rating. Sixteen genotypes viz., NDUK-15-222, SRI, IPU-2-43, TBG-130, TBG-104-1, TBG-129, Butta Minumu, OBG-32, KPU-12-213, Tuti Minumu, VBG 12-111-1, LBG-787, GKB-3, LBG-623 and LBG-685 were recorded to be moderately resistant with 2 scale rating. Whereas TU-40 and LBG-752 genotypes are found to be moderately susceptible with 3 scale rating. The genotype LBG-20 found susceptible with 4 scale rating followed by two susceptible checks viz., TBG-104 and LBG-645. In case of YMV among screened genotypes none of the entry recorded zero scale rating which comes under highly resistant. While 11 genotypes viz., PU-31, TBG-130, GBG-1, NDUK-15-222, LBG-787, LBG-623, IPU-2-43, Tuti Minumu, KPU-12-213, LBG-752 and TBG-129 were recorded less incidence of YMV and found to be resistant with 1 scale rating. The remaining 7 balckgram genotypes viz., Butta Minumu, GKB-3, TBG 104-1, VBG-12-111-1, LBG-20, LBG-685 and SRI recorded to be moderately resistant with 2 scale rate. But two genotypes viz., OBG-32 and TU-40 were found to be moderately susceptible with 3 scale rating along with two susceptible checks TBG-104 and LBG-645. The results indicated that none of the genotype found to be susceptible and highly susceptible during rabi 2018-19.
Yellow Mosaic Virus (YMV), leaf curl, blackgram genotypes.
Blackgram, Vigna mungo (L.) Hepper which is commonly called as urdbean is the fourth important pulse crop in India. India is the world’s largest producer as well as consumer of balckgram. In India, the area, production and productivity of Pulses were 24.91 million hectares, 16.35 million tones and 733 kg per hectare, respectively during 2015-2016 (Shani et al., 2017). The annual yield loss due to the insect pests has been estimated at about30 per cent in urdbean and mungbean. On an average, 2.5 to 3.0 million tones of pulses are lost annually due to pest problems (Rabindra et al., 2004). Eleven sucking pests
were identified in blackgram as sap feeders among them whitefly (Bemisia tabaci),thrips (Scirtithrips dorsalis), jassid (Empoasca spp.) and green leafhopper (Nephotettix spp.) and defoliatrs appeared as foliage feeders. Flower thrip (Caliothripssp.) and leaf miner (Chromatomyia horticola) were classified as pollen feeder and tissue borer, respectively. (Kumar et al., 2007). Among them, sucking insect pests such as thrips and whitefly are the most important pests during early stages of crop growth which not only reduce the plant vigour and also act as vectors of deadly viral diseases viz., leaf curl and YMV.
Thrips are the major sucking insect pests in pulses mainly on blackgram and greengram causing consider-able damage by sucking cell sap from different tender parts of plant. And also act as vectors of different plant viruses which cause leaf curl and bud necrosis, besides direct injury by feeding (Ananthakrishnan, 1980). White-fly is another most important insect pest of pulses caus-ing damage by sucking cell sap from leaves or tender parts and excretes honeydew on which sooty mold devel-ops which hinders photosynthesis. Besides, it also acts as a vector for mungbean Yellow Mosaic Virus, (YMV) which is a serious threat to pulse production in India. The mungbean Yellow Mosaic Virus (YMV) disease results in irregular alternate yellow and green chlorotic patches on older leaves and causes complete yellowing of young leaves of susceptible varieties thereby reducing the pho-tosynthetic ability, finally leading to yield reduction to the tune of 25-78 per cent (Vir, 1984). One of the important tool of integrated pest management is host plant resis-tance by use of resistant verities or cultivars, due to its broad adaptability and environmental safety it becomes the best choice to overcome pest incidence.
A field experiment was conducted with blackgram genotypes at dry land farm, S.V. Agricultural College, Tirupati during rabi 2018-19 to identify the resis-tance source for utilization in developing the resistant va-rieties of blackgram. A total of twenty blackgram geno-types along with two susceptible checks viz., TBG-104 and LBG-645 were screened to thrips and whitefly inci-dence which transmit leaf curl and Yellow Mosaic dis-eases respectively in blackgram and results are presented in Table 1. The field trial was laid in a Randomized Block Design (RBD) with 20 genotypes along with two suscep-tible check verities was sown after each five lines as treat-ments in three replications. Each entry was sown in a row length of 4 meters with row to row 30 cm and plant to plant 10 cm duly following the recommended agronomic practices (ANGRAU) except plant protection measures.
Thrips population was recorded on top three young leaves and whitefly nymphs were recorded from each leaf let of lower surface of the trifoliate leaf in the middle
canopy using a magnifying lens at weekly intervals on 10 randomly selected genotypes. The per cent of disease incidence was assessed by recording the number of plants showing disease symptoms of leaf curl virus and the total number of plants per row. While the per cent incidence of YMV was given as per disease rating scale. The observations were recorded on total plant stand and those attacked by leaf curl virus and YMV at 70 Days After Sowing (DAS).
The results pertaining to the mean number of thrips and whitefly population was observed in different blackgram genotypes at 35 DAS and 70 DAS and pre-sented in Table 1. The incidence of thrips population was recorded at 35 DAS of blackgram and the entries PU-31 and GBG-1 were recorded lowest incidence of thrips popu-lation with 1.96 and 2.58 thrips per plant on top three leaves while in 12 genotypes viz., IPU-2-43, TutiMinumu, ButtaMinumu, LBG-787, GKB-3, LBG-685, NDUK-15-222, SRI, TBG-130, TBG-104-1, TBG-129 and VBG-12-111-1 population of thrips has recorded with a range of 3.14 to 4.83 thrips per plant on top three leaves and in other genotypes viz., KPU-12-213, OBG-32, TU-40, LBG-623 and LBG-752 the thrips population was observed from 5.24 to 5.96 thrips per plant on top three leaves. But in LBG-20 the highest population was recorded with 6.72 thrips per plant on top three leaves which was more than susceptible checks viz., TBG-104 and LBG-645 (6.13 and 6.47 respectively) (Table 1). In case of whitefly population, the entries PU-31 and GBG-1 were found low preferred by the whitefly (1.3 and 1.50 whitefly/plant on trifoliate leaves from middle canopy). While 12 genotypes viz.,IPU-2-43, Tuti Minumu, Butta Minumu, LBG-787, GKB-3, LBG-685, NDUK-15-222, SRI, TBG-130, TBG-104-1, TBG-129 and VBG-12-111-1 recorded whitefly population with a range of 1.57 to 2.72 whitefly/plant on trifoliate leaves from middle canopy of the plant and an-other 5 genotype viz., KPU-12-213, OBG-32, TU-40, LBG-623 and LBG-752 were recorded moderately high whitefly population with a range of 2.89 to 3.11 whitefly/ plant on trifoliate leaves from middle canopy, where as in LBG-20 the highest population was recorded with 3.52 whitefly/plant on trifoliate leaves from middle canopy along with susceptible checks viz., TBG-104 and LBG-645 (3.48 and 3.92 whitefly/plant on trifoliate leaves from middle -canopy respectively). The incidence of thrips population at 70 DAS was observed similar trend and presented in the Table 1.
The leaf curl incidence was recorded at 70 DAS in 20 genotypes ranged from 5.38 to 48.13 per cent at 70 DAS. The genotype PU 31 recorded significantly lowest leaf curl incidence (5.38 per cent) followed by GBG-1 with 8.31 per cent incidence. Sixteen genotypes viz., NDUK-15-222, SRI, IPU-2-43, TBG-130, TBG-104-1, TBG-129, Butta Minumu, OBG-32, KPU-12-213, Tuti Minumu, VBG 12-111-1, LBG-787, GKB-3, LBG-623 and LBG-685 recorded leaf curl incidence with 11.93 to 36.87 per cent. Whereas TU-40 and LBG-752 recorded high-est leaf curl disease incidence (42.55 and 45.24 per cent respectively) followed by the susceptible checks viz., TBG-104 and LBG-645 with highest incidence of leaf curl (46.89 and 48.13 per cent respectively) (Table 2). The results indicated that PU-31 genotype recorded lowest incidence of leaf curl followed by GBG-1 and found re-sistant with 1 rating scale. Sixteen genotypes viz., NDUK-15-222, SRI, IPU-2-43, TBG-130, TBG-104-1, TBG-129, Butta Minumu, OBG-32, KPU-12-213, Tuti Minumu, VBG 12-111-1, LBG-787, GKB-3, LBG-623 and LBG-685 were recorded to be moderately resistant with 2 rating scale. While genotypes TU-40 and LBG-752 are found to be moderately susceptible with 3 rating scale. The genotype LBG-20 found susceptible with 4 rating scale followed by two susceptible checks viz., TBG-104 and LBG-645 (Table 3). The present results were in conformity with Chaudhry et al. (2007) reported that out of 67 blackgram germplasm lines screened against leaf crinkle virus, among them two lines viz., CM-707 and CH-Mash 97 were found to be moderately resistant and all others were mod-erately susceptible to leaf crinkle virus and all others were moderately susceptible. Chhabra and Malik (1992) tested 70 entries of summer mungbean (V. radiata) germplasm for resistance to thrips and reported that genotypes SML 77, UPM 82-4 and Pusa 107 were identified as tolerant donors to thrips and they can be use in a breeding programme.
In general, the incidence of YMV was less dur-ing rabi 2018-19 and it ranged from 2.45 to 27.67 per cent. The genotype PU 31 recorded significantly lowest YMV incidence (2.45 per cent) which followed by TBG-130 (4.52 per cent), GBG-1 (5.72 per cent), NDUK-15-
222 (7.23 per cent), LBG-787 (7.33 per cent), LBG-623 (7.85 per cent), IPU-2-43 (8.33 per cent), TutiMinumu(8.29 per cent), KPU-12-213 (8.67 per cent), TBG-129 (8.71 per cent) and LBG-752 (9.23 per cent) recorded less than 10 per cent YMV with a range of 2.45 to 9.23 per cent YMV incidence. The genotypes viz., Butta Minumu, (10.56 per cent), LBG-685 (11.41 per cent), GKB-3 (12.08 per cent), TBG-104-1 (15.26 per cent), VBG 12-111-1, (17,42 per cent), LBG-20 (17.67 per cent), and SRI (19.75 per cent) recorded the incidence of YMV with range of 10.56 to 19.75 per cent while the highest incidence of YMV was recorded by OBG-32 and TU-40 with 22.33 and 23.58 per cent along with two susceptible checks viz., TBG-104 and LBG-645 with 25.33 and 27.67 per cent respectively (Table 4). The genotypes were cat-egorized based on their resistant reaction to the incidence of YMV on 0-5 scale rating. The results indicated that among screened genotypes none of the genotype recorded zero scale rating which comes under highly resistant. While
11 genotypes viz., PU-31, TBG-130, GBG-1, NDUK-15-222, LBG-787, LBG-623, IPU-2-43, Tuti Minumu, KPU-12-213, LBG-752 and TBG-129 were recorded less inci-dence of YMV and found to be resistant with 1 scale rating. The remaining 7 balckgram genotypes viz., Butta Minumu, GKB-3, TBG 104-1, VBG-12-111-1, LBG-20, LBG-685 and SRI recorded to be moderately resistant with 2 scale rate. But two genotypes viz., OBG-32 and TU-40 were found to be moderately susceptible with 3 scale rating along with two susceptible checks TBG-104 and LBG-645. The results were indicated that none of the genotypes were found to be susceptible and highly susceptible during rabi 2018-19 (Table 5). The present results were with the conformity of Bag et al. (2014) who reported that four accessions viz., IC 144901, IC 001572, IC 011613 and IC 485638 were resistant out of
344 accessions of blackgram germplasm evaluated for resistance to mung bean YMV. Singh et al. (2008) re-ported that the blackgram genotypes IPU 245, KARS-114, KARS-14 and KUG-50 recorded low YMV incidence due to low infestation by whitefly. Similarly,Yadav and Dahiya (2000) reported that out of thirty genotypes, the maximum incidence of YMV was recorded in Copergoan (70%) and minimum in ML5 (13%).
