Growth pattern of  Hevea brasiliensis  in  the  Konkan   region  of  India   was  studied.   Data  on environmental conditions and girth of plants were collected on monthly basis during the seventh year of planting. The region received  rain only for about four months (June - September) and  had more than seven months of dry period. In summer months ambient temperatures during daytime crossed 36°C and  soil moisture deficits were severe,  Growth occurred during the monsoon period only.  Immediately after the monsoon, though there were no apparent limiting factors, the growth of plants stopped completely. Towards the latter half of the dry period  reduction in girth of trees ranging from 0.2 mm to 0.5 mm was observed, The results indicated that the conditions prevailing from  October to May  would prolong the immaturity period  of Hevea in  the  region.

The leaching effect of different media at different temperatures on the extractable protein (EP) content in examination gloves was studied. The media used were 0.5% ammonia solution, 0.5% sodium Iauryl sulphate (SLS) and 1:1 methanol-water mixture. The effect of chlorination on EP content and the effect of leaching on physical  properties of glove samples were also studied. It has been   found that treatments like leaching in 0.5% ammonia solution or 0.5% SLS solution at 60°C for about 5 min and chlorination can effectively reduce. EP content from latex examination gloves to remarkably low levels.

Ten clones of Hevea brasiliensis were characterised for early yield, girth and bark anatomical traits. Genotypic correlations and  direct/ indirect effects of girth  and  structural traits  with  yield  were estimated.

Laticifer area index at the year of opening was the most reliable parameter for early  prediction of yield which  showed the highest  positive  correlation (r = 0.691; P < 0.01) and  highest  positive direct effect  (1.832)  on  yield  over   the  subsequent  three   years.     The  intensity  of  laticifer anastamosing and   ray  width  also  directly   contributed  to  yield  and   were   observed  to  be independent characters. The number of latex vessel rows showed significant positive correlation with  yield (r = 0.589; P<0.01) but its direct effect was negative.   Correlation of girth, latex vessel density and  latex vessel diameter with  yield were not significant.  These traits and  the number of latex  vessel  rows contributed to yield via laticifer area  index.

Leaf nutrient critical values were established from a data bank of leaf nutrient concentration, soil nutrient status and yield of rubber  (Hevea brasiliensis) in South  India  by applying the principles of DRIS taking into consideration the simultaneous optima  for all the nutrients. The critical level for each nutrient was derived using multiple linear regression model relating  the foliar nutrient concentration with DRIS indices of all the nutrients. These values were compared with the DRIS derived critical levels.   The DRIS derived optima as percentages of dry matter for N, P, K, Ca and Mg were 3.590, 0.258, 1.314, 0.997 and 0.302 respectively.  These values  were  found  to be comparable to  those  derived   by  multiple  as well  as simple  linear  regression  and  the  values reported in the literature.  Many of the constraints associated with the development of critical values through the conventional procedure could be overcome  by this approach.

Detailed  investigations  were  carried  out  on  the ageing  behaviour  of air dried  sheet  rubber prepared  using  sulphuric acid as coagulant, in comparison with that of sheets prepared  using formic acid.  Long term thermo-oxidative ageing of vulcanizates prepared  from the sheets was also studied.   Observations have also been made on the extent of corrosion on coagulation pans and sheeting rollers for a period of two years.  It was found that decrease in the strength of raw rubber sheets prepared  with sulphuric  acid was negligible over a period of one year.  Ageing behaviour  of vulcanizates from sheets prepared  using sulphuric  acid was comparable  to those prepared  using formic acid, if  the recommended  conditions of use are followed.  Corrosion of aluminium pans and sheeting rollers was negligible, when sulphuric acid was used as coagulant and recommended  practices were followed.

Morphological and anatomical observations were carried out on 100 randomly selected wild H. brasiliensis genotypes aged 24 months, belonging to the 1981 IRRDB Brazilian germplasm collection, established at the Rubber Research Institute of India.  RRII 105 and GT 1 were used as checks. The characters studied were girth, bark thickness, number of latex vessel rows in the stone cell occupied zone, total number of latex vessel rows, density of latex vessels, diameter of latex vessels, thickness of latex vessel free zone, thickness of stone cell free zone, average distance between latex vessel rows, total cross sectional area of laticifers and test tap yield. For many of the characters the wild genotypes were inferior to the controls. There was however a wide range of variability for the characters studied.   Among the wild genotypes Matto Grosso accessions showed superiority for most characters, with MT 999 being the most desirable.   The high variability for vital anatomical characters related to yield can be used in crop improvement programmes.