Seed physiology and response to germination conditions

Abstract

This chapter brings together knowledge of the germinationand storage behaviour of quinoa seedsin relation to three general aspects: germinationresponse to different factors and in situations ofstress; tolerance to pre-harvest sprouting and dormancycontrol; and the dynamics of ageing and potentiallongevity of seeds in storage. Quinoa seedsdemonstrate the capacity to germinate at temperaturesaround zero degrees and show tolerance tobrief exposure to freezing in some cases. In general,accessions from saline and arid zones are more tolerantto water stress and salinity, as a result of theiradaptation. Nonetheless, the distinctiveness of theionic and osmotic components of salinity has revealeddiverse responses and levels of tolerance inaccessions of different origins. Pre-harvest sproutinglimits the expansion of quinoa cultivation to humidregions. The study of the germination behaviourin accessions with dormancy made it possibleto determine the effect of different factors: environmental(temperature and photoperiod), hormonal(ABA and GA3) and structural (coat thickness), onthe level of dormancy of quinoa seeds during development,ripening and storage. Quinoa seeds havethe capacity to tolerate water loss and maintain viability,recovering vital functions when rehydrated.The kinetics of the reactions of deterioration leadingto a loss in viability are largely determined bythe degree of water mobility in multilayers. Thereactions of deterioration include lipid peroxidationand the formation of compounds from the Maillardreaction. There are references to the differences instorage tolerance for different cultivars, althoughthese are inconclusive in terms of the link betweenlongevity and the characteristics of the regions oforigin.