Summary• Cereal grains differ greatly in their reponses to anaerobiosis. Here, the in vivo conversion of carbohydrates to ethanol and CO 2 under anoxia is reported for three cereal grains.• The conversion of glucose, fructose or sucrose to ethanol under anaerobic conditions was investigated in rice ( Oryza sativa ), barley ( Hordeum vulgare ) and wheat ( Triticum aestivum ) grains; alcohol dehydrogenase (EC 1.1.1.1) and pyruvate decarboxylase (EC 4.1.1.1) activities were also analysed under aerobic and anaerobic incubation.• Our data suggest that rice grains are able to produce ethanol under anoxia for the whole period of anoxic treatment, whereas barley and wheat grains can produce this terminal product of fermentation only during the first days of anaerobiosis. The level of enzymes involved in the fermentation pathway increases strongly under anoxic conditions in all three cereals.• Conversion of hexose to CO 2 is nearly unaffected by anoxia in wheat, barley and rice, whereas only rice grains are able to degrade and utilize sucrose efficiently under anoxia. By contrast, wheat and barley do not utilize sucrose efficiently under anaerobic conditions.

The germination of developing seeds is very uncommon and is generally associated with deficiencies in abscisic acid (ABA) synthesis or sensitivity. This paper examines the quantitative relationship between the inhibition of precocious germination and endogenous ABA in the embryonic axis (ABAa) of hydrated soybean [Glycine max (L.) Merr.] seeds, isolated after the completion of histodifferentiation and before the beginning of dehydration, as well as the magnitude and evolution of axis sensitivity to endogenous ABA during that period. Developing seeds harvested at 25, 30, 35, 40 and 45 d after anthesis (DAA) were subjected to incubation or washing to induce changes in ABA content. ABA content was measured by radioimmunoassay, using a monoclonal antibody against free ABA. Germinability was measured as the time to 50% germination (t 50 ). Washing and incubation induced eight-and twofold increases, respectively, in the rate of ABAa decline compared with the in planta ABAa decline. The threshold ABAa for inhibition of precocious germination (ABAc) increased slightly from 25 to 40 DAA [1.15 -1.66 mg ABA (g DW) 21 ]. This contrasted with the substantial decline in ABAa [10.90 -2.07 mg ABA (g DW) 21 ] during the same period, and indicated that sensitivity to endogenous ABA of hydrated seeds was initially high and diminished slowly during development. The relationship between (ABAa -ABAc) and t 50 was linear for immature seeds incubated before and after washing. Below the ABAc, there were no differences in the t 50 of 25 -45 DAA seeds. The ABAa contribution to the control of precocious soybean seed germination was evident, although other potentially interacting factors were also present.

In the present paper we demonstrate the ability of maize caryopses to produce a-amylase as well as other enzymes involved in starch degradation under anoxia. Carbohydrates resulting from starch breakdown allow maize caryopses to avoid sugar starvation. Most interestingly, this correlates well with the ability of maize caryopses to sustain relatively prolonged anaerobiosis, in agreement with the hypothesis linking carbohydrate availability to anoxia tolerance.

El objetivo de este trabajo fue analizar la incidencia de las condiciones climáticas sobre el cultivo de Salvia hispanica L., conocida comercialmente como Chía, durante las campañas 2014 y 2015, para la zona núcleo de la pampa húmeda, centro-sur de Santa Fe (Argentina). La siembra se hizo en una parcela de 2 ha en el Campo experimental de la Facultad de Ciencias Agrarias (FCA) de la Universidad Nacional de Rosario (UNR), en la localidad de Zavalla (Santa Fe). Se emplearon semillas provenientes de lotes comerciales cultivados en la provincia de Salta y las evaluaciones durante ambas compañas fueron: altura de plantas, número de espigas por planta, peso de 1000 semillas y poder germinativo de las semillas cosechadas. Se observó que las heladas ocurridas no afectaron el desarrollo del cultivo. Como consecuencia de las abundantes precipitaciones y de las menores temperaturas registradas en la campaña 2014 con respecto a las de 2015, en la primera ocurrió una fuerte incidencia del hongo Sclerotinia sclerotiorum, que provocó que el número de espigas por planta (16) y el peso de 1000 semillas (0.904 g) fueran inferiores a las obtenidas en 2015 (78 espigas/planta y 1297 g el peso de 1000 semillas), junto a la aparición de semillas vanas y a un descenso del poder germinativo. Las condiciones de clima presentes durante el ciclo de cultivo de S. hispanica en la pampa húmeda tienen una incidencia directa en el desarrollo de la planta y en la producción y calidad de los frutos cosechados.