Performance of bacterial wilt tolerant tomato (Lycopersicon esculentum Mill.) genotypes under shade

Abstract

An experiment on the "Performance of Bacterial wilt tolerant tomato (Lycopersicon esculentum Mill.) genotypes under shade" was conducted at the College of Agriculture, Vellayani, during 2000 - 200 I. The experiment was laid out in randomised block design with three shade levels, open, 25 and 50 per cent and replicated thrice. Artificial shade was provided using high density polyethylene shade nets. Ten bacterial wilt tolerant genotypes of tomato collected from various sources along with a susceptible check were used. The results indicated that plant height at flowering, height at harvest, internodal length, leaf length, leaf width and petiole length showed an increasing trend with increase in level of shade, while number of primary branches reduced with shade. Shading prolonged vegetative phase and delayed flowering. Flowers per cluster, percentage fruit set and number of fruits per plant were found unaffected by mild shade of 25 per cent, but under dense shade of 50 per cent, there was marked reduction in all these characters. Fruit characters like fruit length, diameter and fruit weight were found unaffected by shade Yield in open and 25 per cent shade were on par indicating that tomato plant was tolerant to mild shade. There were significant variation for yield among the genotypes. LE 45, LE 34 and LE 22 were identified as superior with tolerance to bacterial wilt and shade. These genotypes are recommended for large scale cultivation in the homesteads after proper multilocational trials. There was significant reduction 'in the incidence of tomato spotted wilt disease under shade. LE 34 and LE 44 were found least affected while LE 22 showed the highest level of incidence. Fruit borer and serpentine leaf miner infestation were also reduced under shade. LE 1, LE 2 and LE 42 recorded the lowest score against fruit borer infestation. Leaf miner infestation was least in LE 2 and LE 42 while the high yielding genotype LE 45 was affected more. Anatomical characters like stomatal density and number of vascular bundles showed a decreasing trend with increase in level of shade. Chlorophyll ~,chlorophyll Q and total chlorophyll contents increased with increase in level of shade. The shade tolerant genotypes showed higher content of chlorophyll under all shade levels. On the contrary, open condition showed maximum accumulation of proline compared to both the shade levels. Mild shade proved favourable for improving the fruit quality in tomato. There was an increase in the content of vitamin C .under 25 per cent shade level. Vitamin A content of fruits were found unaffected by mild shade of 25 per cent. But 50 per cent shade reduced both vitamin C and A contents considerably. The external appearance of the fruits was also superior under 25 per cent shade. Genotype LE 22 was superior for vitamin C content while LE 34 and LE 42 recorded the highest vitamin A content.