Effect of secondary nutrients on yield and quality of turmeric (Curcuma longa L.)

Abstract

Primary nutrients viz. nitrogen, phosphorus and potassium are generally regarded to be instrumental in maintaining growth, yield and quality of crops. The secondary nutrients, sulphur, calcium and magnesium, though reported to play key roles in the growth and development of crops, seldom get the recognition they deserve. There are no recommendations for these nutrients for most crops. At the same time, there are reports of increasing deficiency of sulphur, calcium and magnesium in the laterite soils of Kerala. Turmeric (Curcuma longa L.) is a vital spice crop of the Zingiberaceae family. The rhizome, which is the economic produce, contains an essential oil, curcumin and related compounds as major constituents. There is immense scope for cultivation of turmeric in Kerala due to favourable climatic and soil condition. Turmeric is a crop requiring heavy fertilization for increasing yield and quality. This research programme was taken up to study the effect of secondary nutrients on the yield and quality of turmeric. The field experiment was conducted during 2013-2014 in the farm of the Department of Agronomy, College of Horticulture, Vellanikkara. There were 10 treatments with 3 replications each. Treatments consisted of package of practices recommendations (POPR) of 40 tonnes farmyard manure along with 30:30:60 kg N, P and K/ha and its combinations with S, Ca and Mg applied one and two months after planting. Rhizomes were planted at a spacing of 25 × 25 cm and planting was done on 05 June 2013. Harvesting was done after seven months. Biometric observations were taken at monthly intervals and nutrient contents were analyzed at three and six months after planting and at harvest. Nutrient uptake was also worked out. Curcumin and oleoresin content in rhizomes were also analyzed. The soil pH and chemical parameters were determined before and after the experiment. There were significant differences among the treatments with respect to leaf area index, yield, nutrient content and nutrient uptake. In the case of leaf area index, the treatment receiving Ca as second top dressing (viz. two months after planting) recorded the highest LAI compared to other treatments. Fresh and dry yields of turmeric and benefit: cost ratio was also high in the same treatment. This treatment resulted in the highest uptake of all nutrients except S at harvest. Earlier application of sulphur, calcium and magnesium (viz. one month after planting) also led to higher yield and benefit: cost ratio, confirming the direct positive effect on yield. Absolute control recorded the lowest values for all parameters including yield and quality components. Future research should be focused on altering and testing the dose and schedule of application of S, Ca and Mg, and analysis of their interaction effect to maximize productivity, Application of micronutrients and optimizing their dose and schedule for higher yield and quality should also be attempted.