Germination Strategies of Seeds of Cassia auriculata, a Perennial Weed Species of Arid and Semiarid Regions

The timing of seed germination is one of the critical events that determines the success of seedling establishment in wild species in their natural habitat. This is particularly so in species growing in arid and semiarid regions characterized by seasonal rainfall, which is irregular, often with long dry spells. Germination strategies of seeds of Cassia auriculata (Fabaceae, Caesalpinoideae), a perennial weed species of arid and semi-arid regions, were investigated both in petri plate cultures and under field conditions. The results show that seed dormancy is controlled by both physical (impermeable seed coat) and physiological (presence of germination inhibitors) mechanisms. The seeds are capable of withstanding repeated hydration and desiccation cycles during germination. The seeds sown in cultures as well as in the soil do not germinate simultaneously but show staggered germination over a period of several months. Many of the seedlings dry up during intermittent dry periods but many survive in the field during the ensuing summer months until the next rainy season. Staggered germination and ability to withstand repeated hydration and desiccation cycles are important ecological adaptations to maximize seedling establishment under arid and semi-arid environments. © 2016, The National Academy of Sciences, India.