Untersuchungen zur Ökophysiologie von Nigersaat (Guizotia abyssinica) äthiopischer und indischer Herkunft / Prinz, K. Dieter.

Tese (doutor) - Georg-August-Universität, 1976

Niger, Guizotia abyssinica (L. f.) CASS. (Compositae), originating in the Ethiopian highlands, is an oilplant of regional importance. The plant delivers an oil of high dietetic value and it is little exacting in its requirements in regard of soil conditions, cultivation and fertilizing, and shows high tolerance towards pest and diseases. The reaction of strains from the main areas of cultivation, Ethiopia and India, to temperature, photoperiod and water supply in growth-chamber, greenhouse and field tests was registered. For this, the following parameters were used: days to flowering, shoot length, dry weight, number of flower-heads, and, in the field trials, seed yield. The plant material w\s very heterogenous. The Ethiopian and Indian strains differed in length of vegetation period and in their reactions to higher temperatures and longer photoperiods in respect to their generative development. Temperatures between 0° and 18° C induced flowering or supported it. Optimal temperature for vegetative growth lay between 23° and 28° C, however, this temperature range hindered the flower-induction of the Ethiopian strains. Indian strains showed a typical quantitative short-day reaction, while the Ethiopian strains showed a more qualitative reaction of difierent strength. Here temperatures above 23°C and day lengths of more than 12 hrs. had congruent efiects. According to the strain, the highest seed yields were gained (in the field trials) when fertilising with 30 to 90 kg/ha nitrogen. When increasing the plant density from 16 to 49 plants/m² only the Ethiopian strain reacted with a corresponding increase in seed yield; The Indian strain did not react significantly. The effect of 5 different soil types on the growth of Guizotia was minimal; The best results were achieved on fossile latosol. Significant was the minimal reaction to a culture incorporating difierent hydraulic tensions and remarkable was the excellent growth under waterlogged conditions. Explanations for this phenomenon could be the following: The existance of aerenchyma, whose extent correlated with the water conditions of the soil medium, and of negative geotropically growing roots, which in all probability support the oxygen supply. Knowledge of the variables in the optimal physiological conditions for the difierent strains and origins may be instrumental for the distribution of niger and in the avoidance of failures in future areas of cultivation.