TY  - BOOK
AU  - Zainab H
AU  - Sivakumaran S
TI  - Nutrient status in relation to tree dryness
PB  - Papers presented at the IRRDB seminar 5-8 November 1996 Sri Lanka p17-18
KW  - Latex flow
KW  - Nutrient status
KW  - Rubber
KW  - Tapping panel dryness
N2  - Tapping panel dryness (TPD) on rubber trees are often associated with over-exploitation and intensive stimulation. No explanation as to the casual factors of TPD has yet been found. The pattern of TPD occurrence among trees in a rubber stand suggests relation to soil types and the nutrient status. The objective of this study is to determine the change in nutrients status. The objective of this study is to determine the change in nutrients status in the laticiferous system in relation to the onset of TPD. In a field experiment, latex from trees of clone PB 260 tapped on 1/2S d/3 system stimulated with 2.5;ethephon and from trees tapped on the novel RRIMFLOW system using a gaseous stimulant were collected for a period of 12 months for nutrient analysis. Latex collected from unstimulated trees were used as control. The macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium) and micronutrient (manganese, copper, iron, zinc, aluminium and boron) in the latex was analyzed. Latex flow after tapping, pH, dry rubber content and total solids content were determined prior to analysis. pH of latex decreased markedly with stimulation. Dry rubber content and total solid content in latex were highest in the control trees followed by trees stimulated with 2.5;ethephon and lowest in RRIMFLOW treatment. Nitrogen content was highest in the RRIMFLOW treatment and marked increase in phosphorus concentration observed. Generally, there was a declining trend for magnesium, potassium and calcium concentrations for all treatments. Copper and zinc concentrations decreased with increased period of tapping. Fluctuations in iron, aluminium and boron concentrations occurred indicating a declining trend. It is still early to make any inference from the changes in nutrient status with respect to dryness for the tapping system and stimulation treatments studied. The nutrient parameters can possibly provide valuble information on the state of health of the laticiferous system and may also help to diagnose the onset of the TPD syndrome
ER  -