Effect of ethephon stimulation on natural rubber latex properties ; new insight into ethephon stimulation

INTRODUCTION Stimulation to overcome issues such as high cost of production, in rubber plantations (Vijayakumar et al., 2001; Rodrigo et al., 2012). the intensity of harvesting, ethephon stimulation is used as an excellent strategy to obtain desirable yield Stimulation is not to obtain high yields but to attain a yield more or less equal to any baneful secondary effects of recommended dosages of stimulant is of utmost importance and great care should be taken to avoid any and application frequency. Ethephon directly affects the and may also affect latex physico-chemical parameters


Stimulation
to overcome issues such as high cost of production, in rubber plantations (Vijayakumar et al., 2001;Rodrigo et al., 2012).the intensity of harvesting, ethephon stimulation is used as an excellent strategy to obtain desirable yield Stimulation is not to obtain high yields but to attain a yield more or less equal to any baneful secondary effects of recommended dosages of stimulant is of utmost importance and great care should be taken to avoid any and application frequency.Ethephon directly affects the and may also affect latex physico-chemical parameters further increase (Figure 1a).might have a dual role in latex metabolism and latex et al., 1986).Thiols are the 3 % may be due to enhanced in vitro synthesis of reactive oxygen species (ROS).The free toxic oxygen radicals al., 1996).Thiols act as a potential activator for key enzymes such as invertase and pyruvate kinase (Jacob et al., 1981).
In unstimulated trees, average latex sucrose content sucrose content tended to decrease gradually reaching sucrose consumption is compensated by increased migration of sugar to the treated bark zone by the sink effect of stimulating substances, and higher doses did not improve the production but resulted in a greater sucrose expected due to exhaustion of the carbohydrate reserves further increase of ethephon dosage beyond 3 % caused simultaneous reduction in rubber yield.Therefore, high ethephon doses.
an average dry rubber content of 43 % resulting in 84 g of daily dry rubber yield per tree.The volume of latex ethephon concentration (Figure 1b).Dry rubber content concentration.At 3 % ethephon concentration latex latex reduced to 37 %.When increasing the strength of stimulant further, the volume of latex reduced to 210 mL latex volume resulted at 3 % ethephon concentration and

VFA SUCROSE
Variation of serum sucrose content and volatile fatty acid on many factors such as clone, season and system of tapping.Sucrose provides metabolic energy for rubber on sucrose availability in latex vessels determining the possibilities for an enhancement of invertase activity after treatment (Tupy, 1973).The reduction of sucrose content up to 3 % might be due to the higher metabolic utilisation of sucrose for rubber production and diminished entry of sucrose from the surrounding cells into latex vessels Yield (grams/tree/tap) Magnesium concentration (ppm) Ethephon concentration (%) MAGNESIUM YIELD Variation of serum magnesium concentration and dry under S/2 d3 system Rubber yield of a particular clone in commercial latex production is probably determined not only by the ethephon dosage controlling the biosynthesis of rubber, but also by physiological and biochemical processes the application of 3 % ethephon (100.73 gt -1 t -1 ).Further increase of strength of ethephon negatively affected the dry rubber yield, resulting in 4 % decrease over the yield the above observations that application of higher doses frequency is reduced beyond once in three days.There materials lost during tapping.

Total solid content, dry rubber content and non-rubber content
respectively.With the application of 1 % ethephon, both reduced to 34.6 and 31 %, respectively (Figure 4).
With the gradual increase of ethephon concentration, indirectly indicates the non-rubber content in latex (Figure 4).In unstimulated latex, the average total nonnon-rubber content by 26 %.(Do Kim et al., 1996) and those parameters have an accentuated during the 2 nd or 3 rd subsequent tapping and accounts for the process of increased production (Jacob et al proteins, carbohydrates, lipids, phospholipids and nucleic acids can be attributed to the enhanced re-synthesis of higher dosage of ethephon the biosynthesis process upregulated via enhancement of invertase activity, and up -regulated the physiological processes to regenerate cell inspite of the nutritional level of the tree. Non -rubber content (%) Total solid content, dry rubber content (%) Ethephon concentration (%) ethephon concentrations

Volatile fatty acid number
The volatile fatty acid content in latex increased

Figure 1 :
Figure 1: Variation of (a) serum thiol content and (b) latex volume in latex of RRIC 121 genotype Average volatile fatty acid (VFA) number in unstimulated ethephon, VFA number has increased to an average value Increase of the VFA value can be attributed to achieving optimum condition in latex for bacterial that VFA originate from sugar degradation and their quantity is indeed one of the most important parameters et al., 2014).Although serum sucrose concentration reduced