EFFECT AND INTERACTION OF TEMPERATURE AND PHOTOPERIOD ON GROWTH AND PARTITIONING IN 3 GROUNDNUT (ARACHIS-HYPOGAEA L) GENOTYPES

Effect of temperature and photoperiod and their interaction on plant g rowth and partitioning of dry matter to pods was examined in three sel ected groundnut genotypes viz., TMV 2, NC Ac 17090 and VA 81B. The gen otypes were grown in six walk-in growth chambers which were programmed to simulate three temperature regimes (22/18 degrees C, 26/22 degrees C and 30/26 degrees C day/night) each under long (12 h) and short (9 h) photoperiods. The plant growth rates and partitioning of dry matter to pods were estimated on a thermal time basis. Plant growth rate (PL GR) was significantly influenced by temperature, photoperiod and genot ype, whereas pod growth rate (PDGR) was influenced primarily by temper ature and genotype. The interaction of genotype with photoperiod and w ith temperature was significant for both PLGR and PDGR. For example, a t the 22/18 degrees C temperature regime, VA 81B had a high PDGR, whil e NC Ac 17090 did not even initiate pod growth. The partitioning of dr y matter to pods (Pf) was also significantly influenced by photoperiod , temperature and genotype, and significant interactions were found. P hotoperiod did not significantly affect Pf under the low temperature r egime, but at higher temperatures, partitioning to pods was significan tly greater under short days. Pf of VA 81B was relatively insensitive to photoperiod compared with the other two genotypes. The study provid ed evidence of genotypic variability for photoperiod x temperature int eractions which could influence adaptation of groundnut genotypes to n ew environments.