Abstract
Rose is attacked by thrips, <i>Frankliniella schultzei</i> (Pergande), <i>Scirtothrips dorsalis</i> Hood; aphid, <i>Macrosiphum rosae</i> (Linnaeus); whitefly, <i>Trialeurodes vaporariorum</i> (Westwood); mealybug, <i>Planococcus citri</i> (Risso); foliage feeders and bud borers, <i>Helicoverpa armigera</i> (Hubner); <i>Spodoptera litura</i> (Fabricius) and mite, <i>Tetranychus urticae</i> Koch. As great deal of variation of pest attack to rose varieties exists, role of plant morphological characters in inducing plant resistance need investigation. Rose varieties Barbone rose, cabbage rose, Chinese rose and Gladiator were screened against major pests at Navsari Agricultural University (NAU), Navsari, Gujarat, India. Relationship of each character to pest incidence was established on the basis of correlation. Gladiator was considered as tolerant variety against thrips, blister beetle, castor semilooper, tussock moth and bud borer. Chinese rose was tolerant against aphid while, it was moderately susceptible against thrips (<i>R. syriacus</i>) and blister beetle. Barbone rose was moderately susceptible against castor semilooper and tussock moth. Overall, Gladiator was considered tolerant against majority of pests (except aphid). Plant growth habit exhibited significant positive correlation with aphid. Plant height had significant positive correlation with all the pests except aphid. Higher number of primary branches showed increased susceptibility to thrips, blister beetle, semilooper and tussock moth while, aphid was indirectly related to primary branches. Increased prickle density indicated increased thrips on leaves, larval populations of semilooper and tussock moth. Leaf colour exhibited negative relationship with semilooper, tussock moth and bud. Leaf area also influenced abundance of bud borer significantly. Increased leaf thickness showed decreased defoliator pests. Increased leaf glossiness showed decreased plant susceptibility to thrips, semilooper and tussock moth. Flower colour had negative relationship with semilooper, tussock moth and bud borer. Increased flower compactness indicated increased aphids and decreased thrips and blister beetle. Number of flower petals exhibited significant positive relationship with aphid and negative relationship with thrips and blister beetle. Lastly, number of flowers exhibited significant positive relationship with thrips, blister beetle, semilooper, tussock moth and bud borer while, it exhibited indirect relationship with aphid. Overall, most important biophysical traits of rose varieties grown under open field condition were plant height, number of primary branches, flower (compactness, number of petals and number of flowers/plant) which directly or indirectly influenced plant tolerance or susceptibility against major pests.
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