We compared growth, photosynthetic performance and shade adaptation of rubber (Hevea brasiliensis Muell. Arg.) plants growing in natural shade (33, 55 and 77% reduction in incoming radiation) to control plants growing in full sunlight. Stem diameter and plant height, measured over a 15-month period, were greatest in plants grown in full sunlight, and both parameters decreased with increasing shade. At 7 and 14 months after planting (MAP), total plant dry mass was highest in control plants and lowest in plants in 77% shade. Expansion of the fourth leaf whorl, monitored at 5-6 MAP, was slowest in plants in 77% shade and fastest in unshaded plants, which had more leaves and higher leaf areas and inter-whorl shoot lengths. In response to increasing shade, specific leaf area increased, whereas leaf weight ratio and relative growth rate decreased. Chlorophyll a/b ratio decreased with increasing shade, indicating shade-induced partitioning of chlorophyll into light-harvesting complexes. Compared to the response in unshaded plants, CO2 assimilation saturated at lower photosynthetic photon flux densities in plants in 77% shade, with a lower upper-asymptote to the light response curve. Chlorophyll fluorescence revealed no evidence of sustained photoinhibitory damage in unshaded plants. Dynamic photoinhibition decreased with increasing shade, with the greatest depression in the ratio of variable to maximal fluorescence around midday. We conclude that shade adaptation and shade-induced reductions in dynamic photoinhibition account for the enhanced early growth of rubber in light shade.

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This study attempted to find the significance of tapping panel dryness (TPD) of extensively grown new clones in Sri Lanka, with a view to find possible ways to minimise or overcome this disorder at field level. A survey done for clones RRIC 100, 102, 121 and 130 showed that the incidence of TPD was high when tapping is done in renewed bark compared to that of virgin bark and it increased with the advancement of the tapping panel from B0-1 to Bl-2. Also, % TPD increased with age, immature period, girth of plants, yield and with high intensity of tapping. Generally, the % TPD (partial + full) was high in RRIC 100 (22.5%) and RRIC 102 (19.7%) clones compared to the other clones surveyed. On average in any clone, 40% of the dry trees were with a partial dryness. The estimated average yield loss per tapping panel of RRIC 100 was ca. 20% and for the other clones surveyed it was ca. 15%. Morphologically, the majority of the TPD affected trees were without external symptoms (52%), whilst very few (3%) was with abnormal out growth on the trunk and the rest was with bark necrosis, which is irreversible.Since the TPD incidence was high in shallow areas (<10° land gradient) where water logging and occasional floods occur, such areas should be avoided in planting of rubber in future. Good quality planting material should also be used and the immature upkeep should be of good quality to minimise the immature period and any plant stresses. Implementation of low frequency tapping systems will also be helpful in controlling this disorder.

Growth and photosynthetic performance of banana (Musa sp.) grown in three levels of natural shade (33,

COVID-19 pandemic has become a major crisis in 2020. The pandemic has claimed thousands of lives and is spreading a negative economic impact around the global economy. The pandemic has caused a devastating impact on human life in many of the countries without a clear distinction among developed or developing nations. Sri Lanka is facing the heat of the pandemic gradually since January and has taken various measures to combat the situation. The COVID-19 pandemic forwarded a greater challenge to Sri Lanka since the country has faced various disasters in the recent past and question marks remain about the government’s response. The Sri Lankan government response to the current COVID-19 crisis has been largely successful and is ranked among the best responsive countries in the world. This paper discusses Sri Lanka’s strategies in dealing with COVID-19 pandemic and possible future challenges related to the issue.