MSc

The research programme entitled "Role of mineral nutrition in management of pests in chilli" was undertaken at College of Agriculture, Padannakkad with the objective to assess the effect of mineral nutrients such as potassium, calcium, magnesium, sulphur, silicon, boron, zinc and copper in the pest management of chilli. Two trials were carried out on field from August 2017 to February 2018, and November 2017 to May 2018.
The pot culture experiment was conducted in CRD with two factors at 3 x 4 levels (12 treatments) and three replications each. Plants were raised in pots under three soil nutrient conditions namely: P1: non chemical nutrient level (potting mixture alone); P2: NPK nutrient level (potting mixture with NPK); P3: NPK + Ca + Mg nutrient level (potting mixture with NPK + Ca + Mg). Ca and Mg were given in the form of calcium carbonate and magnesium sulphate respectively. Mineral nutrient mixture of potassium, calcium, silicon, boron, zinc and copper were applied as a foliar spray of 0.8 % at different time intervals. Mineral nutrients mixture for foliar application consist of boric acid – 0.2 %, Copper Sulphate – 0.2 %, and Zinc Suphate – 0.2 %. Potassium Silicate – 0.2 %. The levels of foliar nutrition were F0: no foliar nutrition, F1: one foliar nutrition, F2: two foliar nutrition, F3: three foliar nutrition. First foliar nutrition was done 10 days after transplanting, second application after 30 days of first and third foliar nutrition 30 days after second foliar nutrition. Potassium silicate was given as a separate spray at an interval of 10 days after the application of the mineral nutrition.
The results of the experiment revealed that infestation of mites (Polyphagotarsonemus latus), thrips (Scirtothrips dorsalis) and whiteflies along with their damages were significantly influenced by the soil and foliar nutrition levels and their interactions during both the field trials. In case of mite population
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and leaf curl indices (LCI), plants of P2 level showed maximum values and lowest in P1 level. Among the levels of foliar nutrition, highest values were observed in F2 and minimum in F0. Within the interaction effects, the maximum mite population and leaf curl indices were recorded in T7 and minimum in T1, T2, T9 and T10. Nitrogen, potassium, zinc, copper and silicon had positive correlation with the average number of mite viz 0.123, 0.199, 0.010, 0.280 and 0.003 respectively during both field trials. Calcium, magnesium and sulphur had negative correlation viz -0.130, - 0.222 and -0.07 respectively.
With respect to chilli thrips, plants of soil nutrition level P2 harboured maximum population and minimum in P1. With regard to foliar nutrition, no specific trend was observed. Throughout the season minimum thrips population and LCI was exhibited by the treatments of first level that is T1, T2, T3, T4 and maximum in T8 and T6. Second field trial didn’t show any infestation of thrips.
Concerning whitefly colonies, with the increase in soil nutrition levels from P1 to P3 there was a gradual decrease in the whitefly colonies. Significantly high number of whitefly colonies were recorded on plants of F1, F2 and F3 whereas minimum in F0. Among the interaction effects, T10, T11 and T12 exhibited minimum number of whitefly colonies whereas T2, T7 and T8 exhibited maximum throughout the growth phase in both the field trials. Nitrogen, potassium, calcium, magnesium, sulphur, copper and silicon had significant negative correlation with the whitefly colonies viz -0.752, -0.805, -0.826, -0.471, -0.494, -0.687 and -0.746 respectively during the first field trials.
The effects of mineral nutrients on biometric and yield characters were influenced significantly in both the trials. Treatments of P2 and P3 registered significantly high fruit length, number of leaves, plant height, total biomass and also early flowering in comparison with P1.
The result observed in the plant analysis revealed a maximum mineral concentration in the P3 level and minimum in P1. Variation in the number of foliar nutrition did not affect mineral concentration in the plants. Maximum
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concentration of micronutrients was observed in F3 which was on par with F2 and F1 and minimum in the F0 level. Interaction effect of soil and foliar nutrition levels were not significant for most of the nutrients except potassium and copper. Potassium and copper were found to be maximum in treatments of third soil nutrition level (P3) such as T10, T11 and T12 and also treatments with higher levels of foliar nutrition i.e. T4, T6 and T8. Minimum was recorded in the treatments of first soil nutrition level T1 and T2.
In general soil nutrition with calcium and magnesium supplementation and one foliar application of nutrients is found to be best in minimizing the whitefly infestation. Mites and thrips population did not exhibit a true correlation between the levels of mineral nutrients and their population.