| Popis: |
Wheat is grown under divergent climatic conditions in South Africa, varying from cool short days to warm long days. The purpose of this study was to determine how photoperiod, temperature and vernalization affects wheat grain yield, components of yield and grain protein content. Vernalized and unbernalized seed of four wheat cultivars (Inia, Carina, Kariega and SST 86) were grown in growth chambers comprising two photoperiods and two temperature regimes (photoperiod 11hr/temperature 20-15℃; 13hr/20-15℃; 11hr/15-5℃ and 13hr/15-5℃). Temperature treatments were applied on a 12hr-12hr basis. In the 13hr/15-5℃ treatment the grain yield averaged 11.9g per plant with a 18.5% grain protein content. In the 11hr/20-15℃ treatment the yield averaged 1.7g per plant with a 12.4% protein content. The highest yielding cultivar averaged over all environments was Kariega, yielding 7.5g per plant, with SST 86 the lowest at 4.8g per plant. Vernalized Inia and Kariega yielded 14 to 25% higher, but vernalization did not affect the yield of SST 86 and Carina. The interactions: photoperiod and temperature; photoperiod and cultivar; and photoperiod, temperature and cultivar were significant with respect to grain yield, grain number, mean kernel size and grain protein content. The low temperature (15-5℃) and long photoperiod (13: 11hr) treatments resulted in the highest grain yield, number of grains, largest mean kernel size and higher grain protein content. Grain number was the most variable component of yield and kernel size varied the least. Understanding the cultivar and growth environment interaction is important for yield improvement in different climatic conditions. |
