Nitrogen and phosphorus as macronutrients of cocoa (Theobroma cacao) and their physiological functions in different planting patterns of cultivation in Central Java, Indonesia

Abstract

Plant physiological status during the growing season (specific leaf area (SLA), resorption of N and P)leads to knowing the best plant nutrition management (amount and time) based on the plating pattern. Furthermore, proline and glucose content in root tissues may provide a better technique to represent plant stress conditions. This study aimed to evaluate the SLA, the level of reabsorption of N and P from the leaf, and root proline and glucose content of cocoa plants in different seasons and planting patterns. This study was performed in the fields of Plana village, Somagede, Banyumas, 14 Central Java, Indonesia, and was conducted in December 2015 (rainy season) and October 2016 (dry season) on 7 years-old cocoa plants (Theobroma cacao). Three different planting patterns were observed; (1) only cocoa plants, (2) cocoa and coconut pattern, and (3) cocoa with shading trees. The results showed that different seasons and planting patterns affected each observed parameter differently. Cocoas’ SLA was not significantly different in all areas for both 2015 and 2016. N resorption during the growing season did not change in 2015 and 2016 in all planting patterns, whereas P resorption had a significant change in 2016 in all planting patterns. The proline content was significantly different in June 2015, October 2015, and March 2016 in all planting patterns. The glucose content in roots showed insignificant differences in 2015 and 2016 in all planting patterns. These results also showed that SLA and glucose did respond to season and plating patterns. These parameters are suggested as poor indicators of physiological status. Furthermore, sowing cocoa plants with other types of plants can be used to help farmers and stakeholders in managing cocoa cultivation in efficient and sustainable ways.