Towards the Standardization of Accelerated Aging Test for Pigeon Pea Seeds.

Pigeon pea (Cajanus cajan L.) is a leguminous species used for a variety of purposes, specially as food for humans (as grain) and animals (foliage). Little is known, however, about the requisites of its seeds germination and vigor. The accelerated aging test has been a popular test for the evaluation of the physiological potential of seeds. However, its usage has met limitation with small-seeded species which tend to absorb water rapidly and uniformly; the replacement of water by saturated salt solution has been considered for increasing both the efficacy and the efficiency of this test for this type of seeds. In this work the accelerated aging test, namely, the traditional (with water) and with saturated salt solution were compared as alternatives for the evaluation of the physiological potential of seeds. Five lots of pigeon pea seeds, cultivar Mandarim, were evaluated by germination having as substrate paper and sand, first count of germination, speed of emergence index and seedling field emergence tests. For accelerated aging test with and without saturated salt solution (NaCl), the seeds were submitted to 42 and 45 °C for 24, 48, 72 and 96 hours. An attempt to identify the best day for seedling evaluation was also made, comparing the fourth, sixth, eighth and 10^th day of germination. The results indicated that the exposition of the seed samples to different temperatures and aging periods influenced distinctively their performances and allowed their ranking in terms of physiological potential. The traditional accelerated aging test was most effective using the combination 24 hours/42 °C and the seedlings evaluated after six days of germination; equivalent efficiency resulted from the accelerated aging test with saturated salt solution using the combinations of 48 hours/42 °C with seedling evaluation on the sixth day and 24 hours/45 °C with evaluation on the fourth day