HOST PLANT RESISTANCE IN OKRA GENOTYPES AGAINST MAJOR INSECT PESTS.
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Date
2017-12-02
Authors
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Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra.
Abstract
The present investigation entitled “Host Plant Resistance in okra Genotypes against Major Insect Pests,” was conducted during, kharif 2012 and kharif 2013 in the field and laboratory of the Department of Agricultural Entomology, Dr. P.D.K.V., Akola. Twenty one genotypes of okra were screened for the resistance against major insect pests under field conditions replicated thrice in randomized block design. Among various morphological characteristics studied under field conditions plant height, days to first flowering showed negatively non significant correlation with the fruit infestation. Whereas, length of fruit had significant positive effect on the fruit infestation.
Among twenty one genotypes tested, AKO-114 recorded lowest number of aphids (12.19/ leaf), followed by GDO-21, GDO-2, AKO-107 and AKO-106 with 13.97, 15.96, 16.54 and 16.65 aphids per leaf, respectively. The highest number of aphids were harboured on GDO-3 (29.07) followed by GDO-4 (27.77), Julie (26.99), AKO-118 (24.40), GDO-15 (24.59), DGO-6 (24.66), GDO-1 (25.30) and AKO-45 (25.40) per leaf.
Korchi registered moderately resistant reaction against leafhopper population (2.14 leafhoppers/ leaf). Whereas, highest leafhopper population was recorded on GDO-20 (12.29) and GDO-10 (11.78) per leaf and registered as highly susceptible genotypes.
Significantly lowest number of whitely per leaf was observed on the genotype GDO-4 followed by Arka Anamika. Among all the genotypes highest number of whiteflies was recorded on GDO-20 followed by Parbhani Kranti.
AKO-106, AKO-107, GDO-1, GDO-2, GDO-3, GDO-4, GDO-6, GDO-15, GDO-20, Korchi and Akola-Bahar exhibited 0.00 per cent shoot infestation followed by AKO-45 (0.46 %), AKO-118 (0.93 %), GDO-10 (0.99 %) and AKO-114 (1.81 %). While the highest shoot infestation was recorded in OH-016 (12.37 %), followed by Julie (7.87%).
GDO-2, GDO-15 and Korchi had significantly lowest per cent of fruit infestation caused by E. vitella in both number and weight basis and thus graded as highly resistant genotypes. While, GDO-10 emerged as resistant genotype, followed by moderately resistant genotypes viz., AKO-45, AKO-106, AKO-107, AKO-114, AKO-118, GDO-1, GDO-3, GDO-4, GDO-6, GDO-20, GDO-21 and Akola Bahar. Whereas, Julie and OH-016 registered as highly susceptible genotypes.
GDO-15, GDO-2 and GDO-10 emerged as the most promising genotypes and recorded higher yield i.e. 63.49 q/ha, 63.42 q/ha and 63.07 q/ha, respectively. The next promising genotypes which also yielded more viz., AKO-106 (61.35 q/ha), GDO-21 (57.74 q/ha), Parmil (56.42 q/ha), AKO-107 (56.39 q/ha), GDO-20 (55.07 q/ha) and Korchi (53.51 q/ha).
Mechanism of resistance to Earias vitella (antixenosis and antibiosis) was studied in selected five genotypes under laboratory conditions. Oviposition studies under multichoice test revealed that highly resistant genotype GDO-15 was less preferred for egg laying due to sparse density of trichomes, shortest length of trichomes and low hairiness on petiole of leaf as well as lower surface of leaf, which proved unfavorable niche to female moth for oviposition, as compared to rest of the genotypes with dense pubescence.
Expression of antibiosis to E. vitella differed significantly among five different grades of okra genotypes. Comparatively lowest per cent larval survival, prolonged larval and pupal developmental period were noticed when larvae were reared on the fruit blocks of highly resistant genotype GDO-15. Similarly, less larval and pupal weight, less adult emergence, less female to male ratio, less fecundity, Highest per cent reduction of fecundity of female over highly susceptible genotype, less longevity of male and female were noticed when larvae were reared on same genotype. Whereas, susceptible genotypes had biasness towards emergence of female moth.
The morphological characters of okra genotypes had a great influence on the infestation of pest on shoot and fruit. The genotypes possessing lowest density of trichomes, shortest length of trichomes and low hairiness were found resistant to shoot and fruit borer.
The biochemical content in shoot and fruits as a basis of resistance revealed that highly resistant genotype GDO-15 had high level of total phenol, phosphorus and potassium content and low level of moisture, nitrogen, crude protein and total soluble sugar content. The vice-versa results were found in susceptible genotypes.
Correlation of biochemicals in fruits with the developmental parameters of E. vitella revealed that potassium and total phenol showed the deleterious effect on larval survival, weight of full grown larva, weight of pupa, adult emergence, fecundity, longevity of male and female and also on growth index.
Description
Screening of okra genotypes has done under filed conditions for sucking pest complex and shoot and fruit borer. Various morphological and biochemical components were studied in selected genotypes for shoot and fruit borer. Under laboratory conditions antibiosis and antixenosis mechanism of resistance for shoot and fruit borer was studied.
Keywords
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Citation
KADAM, Miss. PRADNYA SHANKAR. (2017). Host plant resistance in okra genotypes against major insect pests. Department of agricultural entomology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. Ph. D. 2017. Print. xv, 162p. (Unpublished).