RUBBER BOARD BULLETIN- VOL. 28, N0. 2, 2006 ANATOMICAL STUDIES ON REGENERATED BARK OF HAIL DAMAGED HEVEA BRASILIENSIS TREES-A CASE STUDY K.K. Vinod* and Vinoth Thomas Rubber Research Institute of India, Kottayam 686 009, Kerala, e-mail: rrii@vsnl.com *Hevea Breeding Sub-station, Kadaba 574 221, Kama taka E-mail: h bssnet@ru bberboard.org.in [HJ ailstorms are a regular phenomenon in the NorthEast India dur- ing the pre-monsooon period. Though their inten- sity used to be mild, occur- rence of strong hailstorms causing severe damage is not unusual in this region. Hevea brasiliensis Muell Arg., the Para rubber tree is reported to suffer extensively under hailstorm damage. An inci- dence of such a devastating hailstorm was reported from rubber plantations at Agartala, Tri pur a in 1986 (RRII, 1987). A detailed de- scription of this damage and its consequences were re- ported by Meenattoor et.al., (1995), which a yield reduction on regener- ated bark, the production be- ing about 36% less than that of the virgin bark. The present study was aimed at investigating the anatomical differences in hail damaged and virgin bark as a possi- bility of explaining the yield reduction experienced and other anatomical c onse- quences of wound healing process. A severely damaged done evaluation trial, planted dur- 9 ing 1980 at the Research Farmofthe Rubber Research Institute of India at Taranagar, Agartala (91"15'E; 23°53'N; 30m MSL) constituting five clones viz., RRII 105, RRII 118, RRII 203, RRIM 600 and RRIM 605 were selected for the study. The trial was planted in randomised blocks with three replications. Five trees were selected randomly from each clone and bark samples were collected at three different loci both at damaged and normal sides. The bark samples were fixed in Form- _ aldehyde-Acetic acid-Alco- hol (FAA) mixture. Sledge microtome sections of 25 Jlm thickweretakenand stained combination of Safra- nin-0 and Fast green F CF for general histology, tannic acid-ferric chloride for tannins Oohansen, 1940) and Sudan III for latex vessels (Premakumari et. al. , 1996). Sections were examined through a projection light mi- croscope for anatomical in- vestigations. Data were analysed statistically. Analysis of variance re- vealed that highly significant variation existed between normal and regen era ted bark for all characters (table 1). Ex- cept for density of tannin filled cells, all other charac- ters showed significant re- duction in regenerated bark than normal bark, whereas tannin accumulation was high in regenerated bark. The clone x side affected interac- tion showed non-significant variation for all clones indi- cating that they suffered equally of hail damage. The mean data on num- ber of latex vessel rows (NLVR), density and diam- eter of latex vessels and den- sity of tannin filled cells are given in table 2. Data on NL VR and density of latex vessels showed no signifi- cant variation among clones in virgin bark. However, on regeneration these two traits showed significantvariation among clones. In renewed bark, RRIM 605 had the high- est average number of 7. 93 rows of latex vessels while RRIM 600recorded the low- est of 6.07 rows. On the con- trary, RRIM 600 had more vessels per unit area (56 . 16/ mm) while RRIM 605 re- corded theleast(44.44/mm). This indicated that response