Observations indicated that climate uncertainties are increasing the number of casualty of young plants immediately after field planting. Symptoms of drought are manifested on young plants during summer and life saving irrigation is increasingly being practiced in very young holdings even in the traditional rubber growing regions to tide over drought. In addition to the already recommended summer management practices, tilling of the plant basin at the end of the rainy season increased soil moisture storage, reduced casualty during summer and enhanced growth of young plants. This may be a good practise to manage drought in young plantations.

A glass house experiment was conducted with polybag plants of clone RRII 105 to study the effect of potassium and silicon in alleviating the adverse effects of soil moisture stress in young rubber plants. The experiment consisted of two treatments, viz, irrigated and unirrigated. Under each treatment, there were four sub-treatments viz, control (standard practice), silicon (Si), potassium (K) and silicon + potassium (Si+K). Silicon was supplied as rice husk ash, and incorporated into the soil, two weeks after planting. In treatments with potassium, 2.5 times the recommended dose of K was added so that N:K was maintained as 1:1. Observations on leaf water potential and chlorophyll content index indicated positive effect of silicon and higher dose of potassium in overcoming soil moisture stress.

The increased unsaturation of lipids in plant cell membranes is considered as a necessary adaptation to cold stress. Fatty acid composition of leaf polar lipids in different Hevea brasiliensis clones was analyzed and the double bond indices computed. The main unsaturated fatty acids in the leaf polar lipids of H. brasiliensis were palmitoleic acid, oleic acid, linoleic acid and linolenic acid. Palmitic acid and stearic acid were the main saturated fatty acids. The double bond indices of leaf polar lipids in different Hevea clones varied significantly. Among the clones, the highest double bond index was noticed in RRIM 703, suggesting that it would be the most cold tolerant clone.

Meghalaya is one of the potential areas in North East India where natural rubber can be successfully cultivated. However, the sub-Himalayan conditions prevailing in this part of the country, particularly low temperature conditions during winter can be inhibitory to growth in the initial stages while summer temperatures are congenial. It has been observed that low air temperature plays a very important role in defoliation, refoliation and seed production in the region. Warmer winter conditions may increase survival rate and shorten gestation period. Early leaf fall and refoliation lead to early production of extra-floral nectar and helps seed production. This also helps in escaping from Oidium incidence. Thus a small shift in the climate can have significant impact on rubber cultivation in North East India. Gradual warming may make winter less severe and more areas in the North East may become suitable for rubber cultivation in the years ahead.

An experiment was conducted at Regional Research Station, RRII, Dapchari, Maharashtra to find out the tolerance of modern Hevea clones to drought stress at the early stages of growth. Six months old young plants of Hevea clones (RRII 105, RRII 208, RRII 414, RRII 429, RRII 430 and RRIM 600) were used in this study. The maximum temperature during the study period ranged between 35.5 to 43.0 ⁰C. Visual observations on drought injury indices viz., scorching, leaf yellowing, drying and leaf fall were taken at frequent intervals (once in 4 days) after imposition of drought both in the polybag and field grown plants. Clone RRII 429 showed relatively higher scorching than the other clones. In the polybag plants, leaf yellowing was minimum in clones RRII 429 and RRIM 600, while other clones showed more leaf yellowing after 26 days of drought imposition. Clones RRII 429 and RRII 208 showed higher percentage of drying and leaf fall in the polybag plants while clone RRII 430 had the least. Similar observations have been made under field condition for these clones. Results from the field observations showed that clone RRII 430 was more tolerant to drought stress than RRII 414 under field conditions.

Apiculture and commercial honey production in Kerala mainly depend on the rubber plantations. Rubber, Hevea brasiliensis Muell Arg. yields both latex and honey (nectar). The latex is produced by the laticeferous cells in the bark and nectar exuded from the extra-floral nectaries at the junction of the trifoliate leaf petiole. The leaves of rubber tree shed during December-January. Generally the shedding of older leaves commences in the Northern parts of Kerala during December and extends up to January in Southern parts. After this, refoliation starts almost within one or two weeks depending on the weather conditions. The occurrence of rainfall during these period results in the infection of tender leaves Oidium causing leaf shedding, affecting seriously the nectar secretion. The young leaves at half maturity (light green colour) secrete nectar through extra-floral nectaries situated at the junction of the petiole. The honey flow begins in Northern districts of Kerala during January- February months and it extends up to February- March in Southern districts. A study was conducted by AICRP on Honey bees and Pollinators at Vellayani centre to correlate the influence of untimely rainfall and honey yield in rubber. Weather conditions influenced the secretion of nectar from the extra floral nectaries. Rain washes away or diluted the nectar from the leaves resulting in severe economic loss to the beekeepers. The increased relative humidity during the refoliation period due to untimely rainfall paved way for the incidence of powdery mildew (Oidium heveae Steinm) on tender leaves. The leaves showed powdery/ashy coating, curling, crinkling and edges of leaves rolled inwards resulting in leaf fall within a week. The average honey yield and data on summer rain for the last five years showed that the untimely rainfall in 2008 honey flow season negatively affected honey yield. The secretion of extra floral nectaries and in turn the production of honey from the rubber plant are related to the prevailing weather and climate change especially too much rains during the nectar secreting season will be harmful for honey production.