Standardisation of index leaf/leaves for assessing the nutritional status of clove in relation to soil fertility

Abstract

Clove being an elite spice of immense economic and gastronomic importance, it was felt necessary to undertake an investigation in to the fertility status of the major clove growing soils of Southern Peninsula with special reference to Trivandrum district of Kerala and Kanyakumari district of Tamil Nadu and also the mineral nutrition of the crop in relation to the fertility of the soils in which they flourish. The investigation was also aimed at establishing the index leaf/leaves for the formulation of a more pragmatic and scientific fertilizer recommendation. With a view to achieve this aim, four major clove growing regions viz., Vithura, Pattom, Vellayani of Trivandrum district and Kulasekharam of Kanyakumari district of Tamil Nadu were chosen for the study. The soil types encountered at Kulasekharam and Vithura were forest soils, whereas laterite soil was encountered at Pattom and red soil at Vellayani. Soils from three different radii (0.5, 1.0 and 1.5 m) from the base of the plant were collected, composited, sampled and analysed. Leaves from clove plants were collected immediately after the completion of flushing. The tree canopy was divided equally in to three regions viz., top, middle and bottom. Three samples each from these regions were drawn by collecting the first, second and third whorls from the apex of the branchlets oriented towards the east, west, south and north. Leaves from the first whorl, second whorl and third whorl from each direction were pooled, sampled and analysed. The soil available and plant N, P, K, Ca, Mg. CU, Mn and Zn were correlated to find out their relationships. Yield data for two year from all the four locations were also correlated with the significant correlation values obtained from the correlation studies between soil available nutrients and their respective leaf nutrient concentration. As a result of the study, it was brought out that forest soils of Kulasekharam with high organic matter and CEC and having a clay loam texture were found to be better suited for clove cultivation as compared to the other soils studied. The highest yield was also obtained from Kulasekharam, while lowest yield was noticed at Vellayani. The leaf nitrogen concentration was found to be the highest in whorl 1 of the top region of the plant canopy. In the case of phosphorous, the whorl 1 leaves of bottom region were proved to be richest. The leaf potassium was found to be the highest in whorl 1 of the top region of the plant. Calcium concentration in the leaves was found to be the highest in whorl 111 of bottom region, while magnesium concentration was the highest in whorl 111 of the top region. Copper, manganese and zinc in the leaf were found to be the highest in the whorl 111 of the bottom region. Based on the correlation between soil available nutrients and the respective leaf nutrient concentration and also the correlation between leaf nutrient and yield, the following index leaves were identified in relation to different nutrients. 1. Nitrogen - leaves of whorl 1 of top region 2. Phosphorous - leaves of whorl 1 of bottom region 3. Potassium - leaves of whorl 1 of top region 4. Calcium - leaves of whorl 111 of bottom region 5. Magnesium - leaves of whorl 111 of top region 6. Copper, manga- - leaves of whorl 111 of bottom region nese and zinc Though the present study has yielded several valuable findings, further indepth studies are necessary to fix the critical limits of each nutrient through field trials involving graded dose of fertilizers for the formulation of a more pragmatic and sensible fertilizer recommendation for the crop. Moreover, an extensive investigation on the lines of present investigation involving large number of clove plants from several location or from a single location is necessary to confirm the present finding obtained from this basic study.