SCREENING OF GENETICALLY DIVERSIFIED BRASSICA GENOTYPES AGAINST APHIDS

Abstract

Screening of Brassica oilseeds genotypes belonging to four Brassica species including Brassica napus, Brassica Juncea, Brassica campestris and Brassica carinata was carried out under field and screenhouse conditions during crop season 2006/07 and 2007/08. Under field conditions average aphid’s density per plant was at peak during the 2nd and 3rd weak of February. Although non of the 12 genotypes was completely free of aphid attack under field conditions, nonetheless based on aphid density, Vangard with lowest aphids population (12.84 aphids/plant) was found to carry some resistance against aphids attack whereas genotype Legend with highest aphid density (37.94 aphids/plant) was on the other extreme. With respect to yield and its components, highest values for seed yield (2386 kg/ha), plant height (214.3cm) and number of branches/plant (19.20) were recorded in Peela Raya, whereas maximum 1000 grain weight (4.80g), siliqua length (8.31cm) and seed/siliqua (23.57 seed) were found in Westar, Ganyou-5, and Oscar, respectively. Highest oil, protein, oleic acid and moisture contents were found in Oscar (52.10%), T-16-401 (25.12%) and Oscar (7.09%) and lowest percentage for glucosinolates, linolenic acid and erucic acid were found in Rainbow (67.35 μm g-1), Ganyou-5 (8.78) and Crusher (36.44), respectively. Under screen-house conditions, with artificial infestation of 0, 5, 10 and 15 aphids/plant at flower-bud initiation stage in 12 Brassica genotypes, overall seed yield losses ranged from 11.08 to 75.88% from aphid’s density of 37.33 and 132.7/plant in T-16-401 and Vangard, respectively. Lowest average percent losses in seed yield, straw yield, plant height and branches, were recorded in T-16-401 (23.18), Ganyou-5 (20.35), Peela Raya (25.32) and T-16-401 (6.25) with average aphid’s density/plant of 59.00, 37.83, 65.72 and 59.00. Losses in both, siliquae mr-1 and leaves, were found in Westar (16.24%) and (7.21) with average aphids density/plant of 108.2. Highest average percent losses in Brassica oil and moisture contents were recorded in Oscar (5.90), and T-16-40 (21.27) with aphids density of 113.9 and 59.00 per plant, while highest percent gains in protein, glucosinolates, oleic acid, linolenic acid and erucic acid were recorded in Oscar (24.57), Rainbow (37.07), T-16-401 (19.82), Westar (13.93) and Legend (31.38) with aphid’s density of 113.9, 138.9, 59.00, 108.2 and 114.8 per plant. Among the Brassica napus group the lowest yield losses (16.25%) were recorded in Legend from 69.67 aphids/ plant. Overall, among the 12 genotypes Vangard, Crusher and Legend were the best. Based on comparatively better performance against aphids attack and making minimum compromise on yield and yield components and exhibiting increased oil recovery, the Vangard, Crusher and Legend were found best among the genotypes included in the study.