Conservation of Hibiscus acetosella germplasm by seed cryopreservation

Hibiscus acetosella (Malvaceae) is a shrub of great importance for landscaping, food and medicinal purposes. The objective of this study was to preserve H. acetosella germplasm by seed cryopreservation. Half of the seed batch was scarified and the other half was kept intact. Cryopreservation occurred by immersion in liquid nitrogen for 1 hour. Moisture content (MC%), germination percentage (G%), germination speed index (GSI), normal seedling formation (NS%), shoot length (SL), dry matter (DM), biometry and plant survival were evaluated after treatment. MC% ranged between 7.7% and 6.65% in intact and scarified seeds, respectively. Scarification raised G% and GSI compared to intact seeds. Intact and scarified seeds had 100% and 70% NS%, respectively, when not cryopreserved. Cryopreservation reduced NS% to 62% and 12.75%, respectively. The highest SL was observed in intact and non-cryopreserved seeds, with an average of 10.21 cm in height. However, the cryopreservation of intact seeds reduced SL by about 50%, and scarification led to a further reduction, either with (3.32 cm) or without (2.47 cm) cryopreservation. Seedlings from intact and non-cryopreserved seeds showed higher DM in relation to seedlings from cryopreserved seeds. The association of cryopreservation and scarification further reduced DM. The cryopreservation of intact seeds yielded 100% survival at the end of the acclimatization process. However, cryopreservation of scarified seeds reduced the survival percentage to 15%. Changes in color were observed for seeds scarified and subjected to cryopreservation. Thus, cryopreservation is considered an efficient technique for the conservation of intact H. acetosella seeds in the long term.