CO2, light and temperature influence senescence and protein degradation in wheat leaf segments

Effects of environmental conditions influencing photosynthesis and photorespiration on senescence and net protein degradation were investigated in segments from the first leaf of young wheat (Triticum aestivum L. cv. Arina) plants. The segments were floated on H2O at 25, 30 or 35°C in continuous light (PAR: 50 or 150 µmol m−2 s−1) in ambient air and in CO2-depleted air. Stromal enzymes, including phosphoglycolate phosphatase, glutamine synthetase, ferredoxin-dependent glutamate synthase, phosphoribulokinase, and the peroxisomal enzyme, glycolate oxidase, were detected by SDS-PAGE followed by immunoblotting with specific antibodies. In general, the net degradation of proteins and chlorophylls was delayed in CO2-depleted air. However, little effect of CO2 on protein degradation was observed at 25°C under the lower level of irradiance. The senescence retardation by the removal of CO2 was most pronounced at 30°C and at the higher irradiance. The stromal enzymes declined in a coordinated manner. Immunoreactive fragments from the degraded polypeptides were in most cases not detectable. However, an insolubilized fragment of glycolate oxidase accumulated in vivo, especially at 25°C in the presence of CO2. Detection of this fragment was minimal after incubation at 30°C and completely absent on blots from segments kept at 35°C. In CO2-depleted air, the fragment was only weakly detectable after incubation at 25°C. The results from these investigations indicate that environmental conditions that influence photosynthesis may interfere with senescence and protein catabolism in wheat leaves.

Luxembourgish farmers lack information about grain legume cultivation

Grain legume production in Europe has decreased in recent years, while legume demand has rapidly increased due to growth of meat production. Therefore, Europe imports grain legumes, principally soybeans, to meet feed protein requirements. Various investigations have identified problems and benefits of local grain legume cultivation. Nevertheless, grain legume cultivation has still not increased in the last years. Studies investigating why farmers do not cultivate grain legumes are missing. Here, we surveyed the knowledge of farmers about grain legume cultivation, problems and constraints of grain legume cultivation and the barriers faced by and incentives needed by farmers. We sent a questionnaire to 1373 farmers in Luxembourg, with a response rate of 29 %. Results show that only 17 % of all the responding farmers cultivated grain legumes; 88 % of the conventional farmers did not cultivate grain legumes, while 85 % of the organic farmers did. We observed that Luxembourgish farmers feel badly informed about grain legume cultivation; organic farmers generally feel better informed than their conventional colleagues. The main barrier, named by Luxemburgish farmers to not cultivate grain legumes, is not economic issues but a lack of knowledge and extension services for these crops. Main incentives needed to start grain legume cultivation in the future are economic issues. Even though grain legume producers mentioned several negative experiences with grain legume cultivation, they are not discouraged by the poor economic conditions and appreciate the benefits of grain legume cultivation. Overall, our findings show that research results on grain legume should be better disseminated to extension services and farmers.