ABSTRACT
SUMMARY. Rubber production has been extended to many sub-optimal environments worldwide during late 1970s. Prominent among them are northeast India, highlands and coastal areas of Vietnam, southern China and southern plateau of Brazil. In addition to near-ideal growing conditions, these areas offer stresses like low temperature, higher alti tude, diseases and wind. South China experiences all these stresses due to expanse of land mass and extremely diverse climate. A number of rubber clones are being evaluated along with derivation of new
INTRODUCTION
Para rubber (Hevea brasiliensis Muell.-Arg) is native to rain forests of the tropical region of the Great Amazonian basin of South America. This area falling between equator and 15° S is characterized by a wet equatorial climate (Strahler, 1969). Brazil offers attributes ideal for rub ber cultivation, viz., 2000-4000 mm rainfall distributed across 100-150 rainy days per annum (Pushparajah, 1977; Yew, 1982; Watson, 1989); (b) mean annual temperature of around 28 + 2°C with a diurnal variation of about 7°C (Barry and Chorley, 1976) and (c) sunshine hours of about 2000 h/per year at the rate of 6 h per day in all months (Pushparajah, 1977; Yew, 1982; Ong et al., 1998). The Amazon Basin is the largest area in the world with a typical equatorial climate, without any real dry season (Pushparajah, 2001). However, the occurrence of South Ameri can leaf blight (SALB) caused by the fungus Microcyclus ulei (P. Henn.) v. Arx makes the area inhospitable for rubber cultivation. Senai of Malaysia (1°36 N'; 103°39' E) has been adjudged as the most suit able for rubber cultivation and production (Rao et al., 1993).
