Biomass allocation and growth performance of Tithonia diversifolia (Hemsl.) A. Gray in coconut plantations in Sri Lanka

Abstract

Coconut is a popular plantation crop with a growth habit requiring wide space between palms. With the amount of sunlight that reaches coconut understory, the between-palms space can be used to grow other beneficial plants. Growing fertilizing shrubs within coconut rows can contribute to effective and sustainable use of coconut plantation soil. In the long term, sustainable coconut plantation systems will require shrubs that sprout quickly after periodic cutting to provide sufficient plant nutrients. Here, we report the results of a 4-year experiment on Tithonia diversifolia (Hemsl.) A. Gray biomass allocation and growth performance in coconut plantations in Sri Lanka. Effects of growing T. diversifolia, pruning frequency and its green manure application on soil properties, moisture, organic matter, bulk density and microbial activity were assessed in two agro-ecological research stations. Results revealed increasing dry foliage and wood biomass overtime. At higher pruning frequencies, foliage biomass increased while wood biomass decreased. Inversely, at lower pruning frequencies, wood biomass increased while foliage biomass declined. Growing T. diversifolia in coconut plantations had little effect on soil moisture content especially in humid area. In the long run, mulching reduced bulk density, improved soil nutrient, organic matter and microbial activity and palm leaf macronutrient levels. This study shows that T. diversifolia, when used as green manure crop in coconut plantations, has a great fertilizing capacity and potential to improve in the long term, not only the soil properties, but also the nutrient levels in the palm organs.