Secagem, armazenamento e condicionamento osmótico de sementes de frutíferas nativas do cerrado

Abstract

The objective of this study was to evaluate the sensitivity to desiccation and storage of seeds of Eugenia pyriformis (uvaia) and desiccation tolerance, storage and priming of seeds of Psidium guineense (guava) and Alibertia edulis (Rich) A. Rich. ex DC (quince), native of Savannah. The fruits used were collected from headquarters in the city of Dourados-MS, Amambai-MS and Rio Brilhante-MS, and benefited at the Laboratory of Nutrition and Metabolism of Plants from the UFGD. To study the desiccation sensitivity of uvaia seeds a protocol was used based on the reduced level of hydration of the seeds every five percentage points, resulting in seeds with an initial moisture content of 45%, being reduced to 40, 30, 25 , 20, 15, 10 and 5%. To assess the longevity of uvaia seeds during a storage period of 30 days, the following conditions were tested: cold and dry chambers (16 ± 1 º C/40% relative humidity), refrigerator (5 ± 1 º C), freezer (-18 ± 1 º C) and the seeds that were not subjected to storage constituted the control treatment. To evaluate the desiccation tolerance on guava seeds and the effect of drying on the quince seeds a protocol was used based on the reduced level of hydration of the seeds every five percentage points yielding seeds with moisture contents of 15, 10 and 5 %. To study the longevity of seeds during storage, five storing conditions were tested: laboratory (25 ± 1 º C/50% relative humidity), cold and dry chambers (16 ± 1 º C/40% relative humidity), refrigerator (5 ± 1 º C), freezer (-18 ± 1 º C) and the seeds that were not subjected to storage constituted the control treatment. The guava seeds were stored for 90 days and the quince seeds for 30 days, both with moisture contents of 5 and 10%. To study the effect of priming in guava and quince seeds, the seeds were soaked for 5 and 10 days in the following solutions of polyethylene glycol 6000: 0.0 MPa, -0.3 MPa, -0.5 MPa, -0.7 MPa and -1.3 MPa. In all the experiments, the experimental delimitation was completely randomized with 4 repetitions of 25 seeds each. The uvaia seeds are sensitive to desiccation and cannot tolerate drying at 5% water content. The reduction of water damaged the characteristics studied. The seeds recently benefited presented germination of approximately 77% and with the dehydration to 5% the germination was reduced to 15%. The storage conditions under low temperatures and drying reduced seed germination, thus indicating a recalcitrant behavior. The guava seeds presented orthodox behavior in relation to desiccation tolerance and storage, due to the maintenance of germination capacity when reaching a water content of 5%. The priming did not increase the germination percentage and seedling growth of guava seeds, however it halved the average time of germination. Quince seeds present orthodox behavior and do not lose germination capacity upon reaching the water content of 5%, even after 30 days of storage, however storage in a freezer is not recommended for these seeds. Quince seeds do not require priming to achieve high germination rates.