Posted on Dec 01, 2010
Nitrogen is one of the essential mineral nutrients required for successful production of grain and biomass crops. Most agricultural soils contain low amount of nitrogen and hence require supplemental nitrogen applied in the form of fertilizer for optimal productivity. But almost all of the previous studies have shown that most crop plants utilize less than half of nitrogen added to the soil with the remaining nitrogen lost through leaching or denitrification, or incorporated into the organic fraction through immobilization. With the cost of chemical fertilizer increasing, growers feel the consequence of this lose more than ever. It is very important that solutions be sought to address this problem either through developing nutrient efficient genotypes to effectively utilize supplemental nitrogen added to the soil or through developing alternative crop and soil management schemes that will minimize the loss.
Results from earlier research have indicated that genotypes and management conditions can significantly influence nitrogen use efficiency in sorghum. Post flowering drought tolerant “stay-green” genotypes have been reported to have improved nitrogen use efficiency over senescent genotypes. Some plant morphological attributes such as leaf thickness and specific leaf weight have been shown to be positively related to nitrogen use efficiency. While such information are useful for better targeting the problem in future research, most of the results so far generated are based on a small set of entries with relatively narrow genetic backgrounds. Evaluation of larger set of genotypes representing an array of genetic backgrounds having contrasting characteristics for traits assumed to be related to nitrogen use efficiency may help generate more robust information.
In this study we plan to evaluate a range of sorghum genotypes including sources known for their reaction to pre and post flowering drought tolerance, stalk rot resistance and yield potential, including elite breeding lines and commercial hybrids. The genotypes will be evaluated in high and low yield and nitrogen loss potential environments under variable nutrient and watering regimes. Data will be collected on several plant and soil parameters at different times during the growth cycle. Nitrogen use efficiency of genotypes in all environments will be determined and related to plant morphological and physiological characteristics. Plant traits found as highly related to Nitrogen use efficiency may be pursued as target for genetic improvement of nitrogen use efficiency. Differences in plant nitrogen use will also be related to agronomic characteristics such as standability, stalk rot resistance and grain quality attributes including test weight grain fill duration, grain weight, protein content and starch structures.