Effect of tapping rest during wintering months on latex yield and tapping panel dryness in three rubber (<em>Hevea brasiliensis</em>) clones

Abstract

Hevea brasiliensis (Muell Arg.) undergoes annual leaf shedding commonly known as wintering. The wintering period in the traditional rubber growing areas in the Wet Zone of Sri Lanka is from December to February followed by flowering and flushing in March. Tapping rest during wintering is recommended in certain countries while in some other countries year round tapping is practiced. In Sri Lanka, until early1970s winter resting was practiced, but this is not being practiced at present. Incidence of tapping panel dryness appears to be high with currently recommended clones and hence the objective of the present study was to investigate on the effect of winter resting on the annual yield and tapping panel dryness in rubber clones. Experimental trials were conducted for two consecutive years (2018 and 2019) with three clones viz., RRIC 100, RRIC 121 and RRISL 203 at the Substation of RRISL at Kuruwita in Ratnapura district. Treatments tested were continued tapping with no winter rest (T1), resting during the wintering period (T2) and once in six days tapping during the wintering period (T3). Trees were tapped at S/2d3(once in three days) intensity. Data were collected on latex volume, bark consumption and TPD incidences. Results for two years showed higher g/t/t/ in all three clones when rested during the wintering period in both years as compared to those with no winter rest. Significantly higher annual total crop (kg) was recorded for T1 when compared to T2 in all three clones for both years. Though total number of partially and totally dry trees of winter rested trees of clones RRIC 100 and RRIC 121 were low, the differences were not significant. In terms of profits obtained as indicated by economic analysis, resting the trees during wintering resulted in the highest profits, followed by d6 tapping during the same period. Winter rest should be tested for a longer duration (4-5 years) for all the clones recommended at present that are vulnerable to tapping panel dryness.

Analysis and prediction of rubber tree phenological changes during Pestalotiopsis infection using Sentinel-2 imagery and random forest

“…The pattern of defoliation and refoliation of rubber trees (wintering period) is used to understand disease spread and severity, as well as to plan or decide on chemical spraying to control diseases. 45 Wintering happens when rubber developed an adaptation to reduce transpiration due to water scarcity during the dry season. Wintering patterns are well known to have an impact on yield.…”

“…Understanding and predicting the leaf phenology changes of rubber trees can help control diseases. The pattern of defoliation and refoliation of rubber trees (wintering period) is used to understand disease spread and severity, as well as to plan or decide on chemical spraying to control diseases 45 . Wintering happens when rubber developed an adaptation to reduce transpiration due to water scarcity during the dry season.…”

“…The analysis of phenological changes of NDVI was investigated using harmonic analysis. The harmonic analysis of NDVI time series aims to characterize the spectral behavior of NDVI by decomposing the time series into a sequence of basic sinusoids and a set of sine or cosine terms with unique coefficients and intercept (harmonic terms) 45 . Time-lag cross-correlation analysis was used to understand the relationship and potential lag (lead effects) between NDVI and climate variables.…”

“…The harmonic analysis of NDVI time series aims to characterize the spectral behavior of NDVI by decomposing the time series into a sequence of basic sinusoids and a set of sine or cosine terms with unique coefficients and intercept (harmonic terms). 45 Time-lag cross-correlation analysis was used to understand the relationship and potential lag (lead effects) between NDVI and climate variables. Cross-correlation measures the similarity between two time series as a function of the time lag applied to one of them.…”

Estimulación de árboles de caucho bajo diferentes frecuencias de sangría en el Noroeste de Colombia

“…Como lo mencionan Silva et al (2012), la reducción del área foliar por la defoliación influye directamente sobre la fotosíntesis neta y, por consiguiente, en el contenido de la sacarosa, que provee la energía requerida para la biosíntesis del látex y que además será demandada durante la renovación foliar y la floración. Seneviratne et al (2020) evaluaron la producción de látex con periodos de descanso de sangría en árboles estimulados, y encontraron que el rendimiento del cultivo se ve significativamente reducido cuando se realiza el sangrado en épocas de defoliación, llegando al máximo en la renovación foliar y floración debido a la utilización de reservas. Además, Figura 3.…”