Rubber Science

SCREENING OF CLONES OF RUBBER (HEVEA BRASILIENSIS) FOR GROWTH AND TOLERANCE TO POWDERY MILDEW DISEASE AT A HIGH ALTITUDE STATION IN KERALA, INDIAResearch Articles
Pages 151 - 155
Thomson T. Edathil, Radha Lakshmanan & Vinoth Thomas
- Abstract
- Keywords
Ten ortet selections and five popular clones of Hevea brasiliensis were screened to ascertain powdery mildew disease tolerance in a high altitude station at Ambalavayal, Wayanad in Kerala. The experiment was conducted during the refoliation from January to April for a period of four years. The plants were protected with alternate application of systemic (carbendazim 0.05 per cent) and non-systemic (wettable sulphur 0.2 per cent) fungicides as per standard practice. Girth of the plants and powdery mildew disease assessments prior to and after treatments were recorded. The ortet selection Iritty 1 showed high degree of disease tolerance with better growth.

Disease screening, Fungicides, Hevea brasiliensis, Ortets, Powdery mildew, Susceptibility, Tolerance

ANATOMICAL CHANGES DURING ACCLIMATIZATION IN SOMATIC EMBRYOGENESIS-DERIVED PLANTS OF HEVEA BRASILIENSISResearch Articles
Pages 156 - 162
P. Kumari Jayasree, Vinoth Thomas & A. Thulaseedharan
- Abstract
- Keywords
In Hevea brasiliensis, though high frequency plant regeneration protocols via somatic embryogenesis have been developed, establishment of these plants in the field has been difficult. A comparison of the anatomical characters of healthy and weak plants derived through somatic embryogenesis, with bud-grafted fieldgrown plants was carried out in detail. Scanning electron microscopy studies on leaves of healthy plants confirmed the presence of epicuticular wax and its continued increase during hardening. In acclimatized plants, the pattern was identical to that of field-grown control plants. Leaves of in vitro weak plants showed less epicuticular wax. Before hardening, stomatal frequency of the in vitro healthy plants was higher than that of the weak ones, but the size of the stomatal aperture did not vary significantly. After acclimatization, stomatal frequency of healthy plants was comparable to, or slightly higher than, that of the control plants. Vascular continuity and distribution of latex vessels in the in vitro plants are also discussed.

Acclimatization, Anatomical changes, Hevea brasiliensis, In vitro culture, Somatic embryogenesis

ENHANCEMENT OF BUD SPROUTING AND GROWTH OF GRAFTED RUBBER (HEVEA BRASILIENSIS) PLANTS UTILISING A POLYHOUSE DURING WINTER IN TRIPURAResearch Articles
Pages 163 - 167
Krishna Das, Debabrata Ray & Sushil Kumar Dey
- Abstract
- Keywords
Winter season (November to February) in Tripura is not conducive for bud sprouting in grafted stumps of natural rubber (Hevea brasiliensis) as the minimum temperature often goes below 15°C during these months. Low temperature during winter inhibits bud sprouting and delays plant growth. To overcome this, the present experiment was designed with bud-grafted stumps grown inside a polyhouse. Regular water spray on the bud patches and soil irrigation were also provided. A much higher temperature than the open ambient air could be maintained in the polyhouse. Due to the effect of polyhouse, evaporation loss was less and hence, a more humid condition was achieved inside. The high temperature and humidity conditions were congenial for better bud sprouting and eventually raising healthy seedlings. Using this simple technique, growers of this region can utilise the winter months also and generate healthy planting materials throughout the year.

Budded stumps, Cold, Polyhouse, Relative humidity, Sprouting, Temperature