EVALUATION OF POLYCROSS SEEDLINGS OF PREPOTENT HEVEA CLONES POTENTIAL FOR YIELD IMPROVEMENT AND DROUGHT TOLERANCE

摘要

A seedling nursery evaluation of nine sets of half-sib seedlings was conducted at Rubber Research Institute of India. The family-wise performance of the progenies was assessed by considering their juvenile yield on test tapping during peak and summer seasons along with seedling girth. An attempt was also made to study their drought tolerance potential by conducting a pot culture study in the second phase along with one set of seedlings of assorted origin. Growth parameters like plant height, girth and number of leaves were recorded at regular intervals during summer and non-summer periods. Visual scoring leaf yellowing was done in pot culture. From nursery evaluation, 126 potential seedlings out of 397 (31.7 %) could be identified with high summer yield. In pot culture study, the highest number of seedlings with green leaves was in the family of PB 28/83. The performance of the family of assorted seeds was inferior to polycross progenies throughout the period. The progenies of clones PB 28/83 and PB 215 were identified as ideal populations for selection and further detailed studies.