Hydroponics as a tool in wheat breeding

[摘要] English: The aims of this study were to evaluate the functionality and the practicality of hydroponics in the process of wheat breeding compared to a conventional glasshouse cultivation method. Furthermore for assessing the screening capability of drought tolerance in wheat cultivars using a hydroponic system was used and morphological yield components were measured and protein concentration fluctuations by means of SE-HPLC were analyzed. x In the first study, five South African wheat cultivars, SST 88, Baviaans, Steenbras, SST 876 and Kariega, were planted into two identical hydroponic systems. A second set of the five cultivars where planted two months after the first planting to separate the two stress periods, the first being drought stress before seed fill and in the second planting, stress was induced at seedling stage. This was done simultaneously. x When maturity was reached, several yield component measurements were taken. x The influences of the drought treatment on the different yield components were established. x Protein extracts of wheat flour were analyzed by SE-HPLC. x SDS was used for the first protein extraction step, and the rest of the proteins were extracted by sonication. 89 x The SE-HPLC method fractionated the storage proteins (both SDS-soluble and SDS-insoluble) into four distinct peaks of decreasing molecular size range, representing mainly larger polymeric proteins (mainly HMWglutenins), smaller polymeric proteins (mainly LMW-glutenins), larger monomeric proteins (mainly gliadins), and smaller monomeric proteins (mainly albumins and globulins). x Relationships between the amount and size-distribution of polymeric and monomeric proteins and flour quality properties were established. x The influence of the drought treatment on protein fractions and quality characteristics was also determined by SE-HPLC. x The results showed that both the genotype and drought conditions had a significant influence on the yield components and protein characteristics. x The use of a hydroponic cultivation method for the induction of drought conditions at any stage of development of wheat can be done at a highly significant level, not only for inducing stresses but for re-establishing and maintaining optimum conditions as well. x SE-HPLC provided a simple and an objective test for measuring the relative size-distributions of wheat storage proteins. x In the second study two South African wheat cultivars, Baviaans and Steenbras, were planted into two identical hydroponic systems (differing only in the makeup of the nutrient solution) and in pots. x Emergence percentages and dates were recorded for a one month period after the emergence of the first seedling in the experiment. x When maturity was reached several yield component measurements were taken. 90 x The two hydroponic systems provided a better emergence environment compared to the potting solution, indicating that there is already a higher potential number of crosses that can be made in the breeding program using a hydroponic cultivation method. x The effect of treatment was highly significant for most of the yield characteristics, indicating that the effectiveness of the treatments played a significant role in the yield potential of each cultivar. x Findings indicated that by using a hydroponic cultivation method instead of the potting method for growing wheat, parent lines can increase the amount of crosses that can potentially be made, thus increasing the amount, potential success and quality of the crosses made, together with the potential of producing seeds that will have the potential of a higher emergence rate. x The hydroponic cultivation method using the chemicult solution proved to be the most effective method of cultivation during this study.

[发布机构] University of the Free State