Practical technologies are required to preserve the viability of seeds particularly those known to be short-term viable species like Carica papaya (papaya). Papaya seeds were imbibed in water or chemical solutions (CaCl2 10-5 M, salicylic acid 10-4 M, and gibberellic acid 10-5 M) combined with inoculation of bacterial cell suspension to determine their effects on seed germination, plant growth, biomass production and chlorophyll accumulation. Seeds imbibed in water germinated 40 % more than control seeds and the time required to reaching 50 % seed germination was reduced two days in comparison to untreated seeds; however, the untreated seeds generated the largest (9.2 cm) and most vigorous seedlings. When seeds were imbibed in CaSG solution, a significant increase of the growth parameters such as fresh and dry biomass weight was observed. Seeds that were primed in gibberellic acid solution followed by inoculation with a mixture of Azospirillum brasilense cell suspension exhibited high seed germination (69 %), plant emergence (47 %) and seedling height (19 %), higher than the control. Differences in chlorophyll accumulation by seedlings were minimal.
Tropical and Subtropical Agroecosystems
INTRODUCTION
Plant development is a programmed process that starts from seed germination to maturity and fruiting. It is mainly modulated by a combination of dormancy, plant cell regulators (Richards et al., 2001, Olszewski et al., 2002, Peng and Harberd, 2002; Sun and Gubler, 2004; Smalle and Vierstra, 2004) and environment factors such as moist, temperature, oxygen, and light (Toh et al., 2008). Identification of triggers of seed germination and seedling growth promotion factors is crucial for the development of
(Andrade-Rodriguez et al., 2008; De Mello et al., 2009; Venier et al., 2012). The germination inhibitors present in the papaya seed testa and sarcotesta control its germination (Chow and Lin, 1991; Paz and Vázquez, 1998) and to eliminate them, papaya growers have applied actions such as removing the sarcotesta from seeds, soaking and washing seeds in water (Mirafuentes, 1997) or sun drying (Jiménez 1996). Growth and development in plants is controlled by the selective removal of short-lived regulatory proteins.
CONCLUSIONS
Seeds that were exposed to a combined treatment, imbibed in G solution and inoculated a cell mixture of Azospirillum exhibited the maximum germination, the greatest emergence, seedling height, and accumulated the highest chlorophyll amount as well. This treatment, which is economic and practical, can be attractive to enhance papaya seed germination capability.