CONICET | Buscador de Institutos y Recursos Humanos

Measurements of water uptake (imbibitions) and oxygen consumption (respiration) are the most common methods to monitor seed germination nawadays1. Calorimetry has proven to be useful in this sense. Previously, we have reported a model to monitor germination of soybean seeds cv. A7636RR2. In order to find out if the model applied to other cultivars of soybean (Glycine max) and to radish (Raphanus sativus, cv. Sparkler), calorimetric experiments of two other cultivars of soybean and one of radish were performed and analyzed. Seeds, cv. Munasqa and cv. DM5.8RR were obtained from the Agro-Industrial Experimental Station Obispo Colombres, Tucumán, Argentina with 95 and 65% germinability, respectively. Radish was acquired from the market. Imbibition curves were performed on individual seeds in chamber at 25ºC. Values of pH were measured each time that seeds were weighed to determine water content. Calorimetric thermal power (P) time (t) curves of germination were also obtained at 25ºC for 10 or more individual seeds after 30 min of equilibration of the system. Calorimetric experiments of germination over 5 mM KCN were also performed to estimate specific imbibitions enthalpies (ih). Calorimetric p t curves could be extrapolated to t = 0 by relating the rate of water uptake as determined from imbibitions curves with p values. Then, p t curves were integrated to determine the specific metabolic enthalpies mh which in turn were related to the water content (WC) of seeds at the corresponding times. The method proved to apply to these cultivars and also to radish. Besides, it was possible to determine the WC that each cultivar needs to germinate. This is very important when breeding new cultivars for water stress tolerance. It was 74, 57, 35 and 64 % for seeds cv. A7636RR, Munasqa, DM5.8RR and radish, respectively.