Allometry, growth pattern and seed germination of brassica juncea(l.) Czern. Var. Ensabi influenced by different light and temperature

ABSTRACT:We studied seed germination, general growth patterns and phenology of Brassicajuncea under different light and temperature regimes in the laboratories, an insect-proof house and outdoor.. Brassica juncea did not display seed dormancyand the rate of germination was temperature-dependent with measurably higher percentages at 25oC vis-a-vis other temperatures. No significant differences were noted in germination percentages among seeds exposed to light (PAR=625 ?mole photon m-2 s-1) and those in darkness. Seedlings subjected to darkness in the growth chamber displayed greater shoot and root lengths compared with their fully exposed counterparts. The shoot length readings were 17.6, 20.2, 22.8, 21.6, 19.5 mm in 15, 20, 25, 30, and 35 ?C, respectively. The parallel figures for fully exposed seedlings were 3.9, 5.6, 6.9, 6.8, 5.6 mm. Distinct manifestation of lag phase in seedling growth was recorded between Stage 1 and Stage 2, otherwise plant growth was rapid. Plants growing under shadow registered plant height was ca. 106 cm, but lower number of flowers/plant , leaves/plant and pods/plant vis-à-vis those subjected to full sunlight and plants that conducted under full sun light registered 23% bigger stem diameter and greater mean leaf number/plant. The number of seeds/pod was similar irrespective of the light regimes that the plants were exposed to.