Micrometeorological modification with mulches to enhance the yield of Turmeric (Curcuma longa L.)

Abstract

Turmeric (Curcuma longa L.) is one of the most important rhizomatous spices, belonging to Zingiberacea. It is an annual herbaceous plant native to tropical SouthEast Asia. Turmeric has high medicinal properties and it is wildly used in pharmaceutical, cosmetics and food industries. Due to the high value of the crop, it is getting good demand all over the world. India is one of the largest producer and consumer of turmeric around the world. In India turmeric is mainly planted in the hot summer months and grown as a rainfed crop, but due to the drastic changes in the agroclimatic conditions its production is influenced detrimentally. Mulching is an important cultural practice in turmeric, which helps to maintain an optimum microclimatic condition, reduce weed growth, add organic matter and conserve moisture throughout the high evaporative periods. Due to these changing climatic conditions assessment of an effective date of planting and finding a most suitable mulching practice are required for the effective production of turmeric. Hence, the goal of this study is to determine how planting dates and micrometeorological modifications with mulches affect turmeric yield. Turmeric variety Kanthi was raised in Plantation Crops and Spices farm, College of Agriculture, KAU, Vellanikkara with four different dates of planting (1st May, 15th May, 1 st June and 15th June) and four different mulching treatments (white polythene mulch, black polythene mulch, paddy straw mulch and green leaf mulch). The experiment was laid out in split plot design with four dates of planting as main plot treatments and four mulching practices as subplot treatments. Crop weather analysis was done by using SPSS software and crop yield prediction model was developed with the help of Principal Component Analysis (PCA) and regression analysis. The total crop period was divided into four phenophases (P1-planting to germination, P2-germination to initiation of active tillering, P3-initiation of active tillering to bulking, P4- bulking to physiological maturity). The days to reach each phenophases were different in every date of planting. May 1st planting took more days to reach 100 per cent germination and to reach physiological maturity both 1st and 2nd dates of plantings took more time. The plant biometric characters like plant height, number of leaves, leaf area, number of tillers and dry matter accumulation were found to be more in earlier dates of planting (May 1st and May 15th) in almost all the time. In mulching practices paddy straw mulch was superior and it was followed by green leaf mulch. The yield produced by May 1st and May 15th dates of planting were on par and in case of mulching treatments paddy straw mulch produced superior yield than any other mulching practice. In mulching treatments polythene mulches recorded more soil temperature and moisture content than organic mulches in almost all the time. The first phenophase of 1st date of planting recorded high maximum, minimum and soil temperature along with less rain fall and rainy days. This might have influenced the late emergence of turmeric. The increase in maximum temperature, wind speed, sunshine hours and evaporation reduced the plant height in third phenophase. Soil moisture content and relative humidity inside the plant canopy showed a positive correlation with yield, whereas soil temperature showed a negative correlation with yield during the bulking stage of turmeric. The decrease in maximum temperature, bright sunshine hours, wind speed and evaporation and the increase in the minimum temperature, forenoon and afternoon relative humidity and rainfall during bulking stage enhanced the yield in turmeric. The development of yield prediction model with principal component analysis of mulching treatments and dates of planting of four phenophases were done and the yields of turmeric crop with these equations were predicted. This showed that, the predicted yield was in accordance with the observed yield in all mulching treatments.