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Sivakumar V.,Agricultural Research Station | Kumar R.M.V.,Institute of Commercial Horticulture | Soorianathasundaram K.,Tamil University
Plant Archives | Year: 2011

Studies were conducted during 2005-07 at Faculty of Horticulture TNAU, Coimbatore on the influence of N and K nutrients (as 50, 75 and 100% of recommended dose of fertilizers through fertigation) on the physiology of mango cv Ratna under high density planting. The nutrient 'P' as applied at recommended dose uniformly to all the experimental plots. In addition to the above levels of N and K, one control plot was maintained having 100% of the recommended dose applied through soil. All the treatments were replicated thrice with six trees of eight years age per plot. The results revealed that among the different treatments tried, application of 100% of the recommended dose of nutrients (100:50:100 g N & K per tree per year) through fertigation has resulted in a superior performance by the physiological parameters which contribute for higher yield namely, chlorophyll a, b and total chlorophyll, soluble protein content, total carbohydrate content, C/N ratio, peroxidase activity in leaves and nitrate reductase activity. The same treatment recorded the least values with respect to total phenol content and IAA oxidase activity.

Devrajan K.,TNAU | Prabhu S.,TNAU | Seenivasan N.,TNAU | Sudha A.,TNAU | And 2 more authors.
Potato Journal | Year: 2011

Three hundred and twenty eight fungus, 178 bacteria and 15 actinomycetes were isolated from the potato rhizosphere soil samples and cysts collected from 67 villages of Nilgiris District. The fungal isolates included 36 Trichoderma, 15 Paecilomyces, 8 Vericillium, 21 Fusarium, 16 Aspergillus and 71 unidentified fungal species, bacterial isolates included 45 Bacillus and 7 Pseudomonas species and actinomycetes included 15 Streptomyces species. The fungal isolates were screened for their antagonistic potential against the potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida based on positive reaction for chitinase activity, antibiotic production, inhibition of egg-hatching and egg parasitization. Positive reactions for chitinase activity, antibiotic production, egg-hatching inhibition and egg parasitization were observed in Fusarium isolate KEUF 255, Paecilomyces isolates NDPL 145, NDPL 264, MOPL 122, THPC 166 and DKPC 132 and Trichoderma isolates NDTH 343, NDTV 364, MOTV 164, EPTV 172, IRTX 176, TKTX 165, BGTV 175 and PNTV 168. They also exhibited the antagonistic potential against Phytophthora infestans in dual plate technique. The bacterial isolates were screened for their antagonistic potential against PCN based on positive reaction for chitinase activity, antibiotic production, acid production, HCN production, egg-hatching inhibition and egg parasitization. Bacillus isolates KEBX296, EPBX147, BGBX135 and KOBX134 expressed positive reactions. Investigation suggests that the virulence of naturally occurring microbial antagonists could be exploited as potential candidates for the management of potato cyst nematodes in the Nilgiri hills of Tamil Nadu.

Anita B.,Institute of Commercial Horticulture | Dinakaran D.,ADACRI | Selvaraj N.,Institute of Commercial Horticulture | Mani M.P.,Indofil Industries Ltd
Pestology | Year: 2011

Tea is attacked by a number of pests and diseases which is the major limiting factor in crop productivity. A majority of tea diseases are of fungal origin and more than 800 species of fungi are reported to affect different parts of the tea plant. Tea being a foliage crop, leaf diseases such blister blight and grey blight are of most concern as they lead to direct loss both in yield and quality. To manage both these diseases a new combination fungicide, AVTAR, containing Zineb 68% + Hexaconazole 4% WP was tested under field conditions at Ooty and Gudalur divisions of Nilgiris district for two seasons(North West Monsoon and South East Monsoon, 2008-2009). The pooled mean of two season experimental results in two locations revealed that foliar spraying of Zineb 68% + Hexaconazole 4% WP @ 250 g/acre at 15 days interval was effective in minimizing the severity of both blister blight and grey blight. The green leaf yield of tea also increased significantly due to this treatment.

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