Effect of high temperature on moisture loss, imbibition and germination in the seeds ofTrianthema Crystallina Vahl. and its distribution

Abstract

The germination behaviour of the seeds ofT. crystallina in relation to its frequent distribution in arid and semi-arid belt of Rajasthan has been investigated. In nature, the seed germination in this weed is definitely effected and to some extent controlled by certain features like light, environmental temperature fluctuations, germination temperature and seed age, and their complex effect seems to be responsible for the complex germination behaviour, and also for the common occurrence and distribution of this species in arid and semi-arid areas of low rainfall in Rajasthan and also in the dry habitats of Australia, Arabia and West Pakistan. The seeds possess endogenous seed coat inhibitor which is removed by washing with running water. Germination is also inhibited by total light and dark conditions, but for the diffused light. Constant low (10 °C) and high temperatures (40 °C and above) have also more or less deleterious effect on germination. However, if the seeds are given some intermittent treatment like low temperature (10 °C) or dilute acid (1%) before germination, they show better germination at slightly higher (35 or 40 °C) temperatures (64% and 40.3% respectively). The older seeds show a quick and higher germination percentage (89.6%) while fresh ones show a sufficiently poor percentage (36.3%) when both were germinated under uniform conditions of temperature (35 °C) and germination duration (96 hours). This is due to a slower moisture depletion and higher as well as faster water imbibition capability of old seeds than the fresh ones under identical treatments and conditions. Thus, the older seeds can retain more moisture for long than fresh seeds at all higher temperatures as the old seeds lose moisture slower than the fresh ones (87.2% and 91.6% respectively) when kept for drying under uniform conditions. The increase in water absorption after imbibition is faster in old seeds (48.4%) as compared to fresh ones (24.3%) and that the former which germinate faster, absorb two times more water than the latter when both are put for imbibition under similar conditions of temperature and duration.