Percentages of cavitation, ratio of cocoa roots vessel structures and soil water content at different soil depths

Abstract

Prihastanti E, Tjitrosemito S, Sopandie D, Qoyim I. 2015. Percentages of cavitation, ratio of cocoa roots vessel structures and soil water content at different soil depths. Pros Sem Nas Masy Biodiv Indon 1: 1689-1692. Cavitation is a process when the vapor enters the water column in xylem causing an embolism. The xylem capacity and embolism symptoms are known as the main cause of stress in plants caused by water.Cocoa rooting is mostly in the depth less than 40 cm that is easily influenced by root hydraulic conductivity (hd) when the soil water content changes. The aims of the study were to observe the ratio of xylem cavitation percentage of cocoa roots, xylem anatomy structure and the soil water content in the depth of 0-15 cm and 15-30 cm of 6-year old cocoa plants. The measurement of cocoa root hd was done using Sperry method performed in 1988 to the root with diameter 3-5 mm. The soil water content measurement was performed using a tensiometer. The result showed that the cocoa root in the depth of 0-15 cm had higher cavitation percentage, which was 35,3%, compared to that in the depth of 15-30 cm, which was 10,7%. Nevertheless, both of the had similar structure and ratio of vascular tissue. Higher root cavitation percentage in the depth of 0-15 cm is possible due to the lower soil water content compared to that in the depth of 15-30%, hence cocoa cultivation system should consider soil moisture and microclimate, thus the water in the xylem flow normally.