Evaluation of nonstructural carbohydrate traits of Napier grass (Cenchrus purpureus) genotypes grown under field drought stress condition
Aster Gebisa1, Ermias Habte2, Abel Gari2, Helen Nigussie1, Chris Jones 2
1Addis Ababa University, Dept. of Applied Genetics, Ethiopia
Napier grass (Cenchrus purpureus Shumach) is a C4 perennial forage grass majorly used as livestock feed in tropical and subtropical environments. However, the productivity of Napier grass is affected by drought stress that in turn inhibits feed quality traits accumulation such as the non-structural carbohydrate (NSC) concentration accumulation and transportation. NSC is one of the cell components that are associated with tolerance to environmental stress such as drought stress as it can minimise the impacts of stress via changes in carbon balance. A study was conducted to evaluate the NSC level of 76 Napier grass genotypes under different soil moisture stress levels (moderate and severe soil moisture stress conditions) and to identify the genetic variants associated with NSC traits. The genotypes of Napier grass were grown either in moderate or severe soil moisture levels using a partial replication design in four blocks. The oven-dried leaf samples that are harvested after eight weeks of growth were ground to quantify water-soluble carbohydrates (WSC) and starch using a spectrophotometer. High variation for NSC and WSC values was observed among genotypes and stress levels. Under moderate soil moisture stress, genotypes that showed high NSC levels were 16797, 16810, and 16802 while, under severe stress genotypes that produce high NSC levels were 16789, 16800, and 1026. Comparing the two moisture stress levels, the highest values for NSC was observed under moderate condition than under severe condition. Furthermore, the genome-wide association study identified two significantly associated SNPs (SGWHAORA00000009_160387802 and SGWHAORA00000009_101547011) in both moisture stress levels. Generally, the concentration of NSC traits was shown to be dependent on the level of soil moisture conditions and genotype.
Keywords: Drought stress, Feed quality traits, key words: Napier grass, non-structural carbohydrate, starch, water soluble carbohydrate
Contact Address: Ermias Habte, International Livestock Research Institute (ILRI), Feed and Forage Development Program, Addis Ababa, Ethiopia, e-mail: e.habtecgiar.org