Genotypic Variation for Stem Reserves and Mobilization in Wheat: II. Postanthesis Changes in Internode Water‐Soluble Carbohydrates

Abstract

Grain filling in wheat crops grown in semiarid regions may depend more on stored water-soluble carbohydrates (WSC) than on current photosynthesis. We evaluated the hypothesis that internode WSC content, specific content (WSC content/internode length), and concentration (WSC content/internode weight) of genotypes affect accumulation and mobilization of stem WSC. Genotypic variation for internode WSC-related traits was measured on the main stem at 10-d intervals in 11 diverse wheats grown under well-watered and droughted field conditions across 2 yr. Relationships among internode WSC-related traits were determined. Date of harvest was the most important factor affecting internode WSC-related traits followed by genotype, irrigation, and year. Genotype 3 date of harvest was the most important interaction. Drought reduced WSC content, specific content, and concentration in different internodes, except WSC concentration in peduncles. Mobilized WSC from peduncle, penultimate, and lower internodes ranged from 70 to 244 mg, from 95 to 227 mg, and from 175 to 450 mg, respectively. The lower internodes provided 51% of the stem mobilized WSC. Mobilized WSC was higher in well-watered than in droughted conditions for penultimate (164 vs. 135 mg) and lower internodes (274 vs. 244 mg). Drought improved mobilization efficiency in the peduncle, penultimate, and lower internodes by 33, 17, and 11%, respectively. Postanthesis maximum WSC content was highly correlated (r 5 0.89 to 0.99) with the amount of WSC mobilized in different internodes, and could be used as a selection criterion to stabilize grain yield under stressful environments.

Heat Stress Adaptation in Elite Lines Derived from Synthetic Hexaploid Wheat

“…The amount of WSC in shoots was also highly correlated to the plant height. This agrees with previous works suggesting that stem reserve potential is determined by both stem length and stem specific weight (stem weight/stem length) (Blum, 1998;Ehdaie et al, 2006;Talukder et al, 2013). The coefficient of determination for the relationship between WSC and plant height was lower under EH than in other environments.…”

Comparison of fructan dynamics in two wheat cultivars with different capacities of accumulation and remobilization under drought stress

“…terminal drought) conditions and reported that the stem of rain fed wheat had higher fructan concentration than that of the irrigated stems. By contrast, in a study in which 11 wheat genotypes were subjected to post-anthesis DS, Ehdaie et al (2006b) reported that DS reduced the WSC content in the different internodes, except in the peduncle. All these results suggest that changes in WSCs under DS can greatly differ among wheat cultivars and stem parts.…”

Carbohydrates Accumulation and Remobilization in Wheat Plants as Influenced by Combined Waterlogging and Shading Stress During Grain Filling

“…There are two factors determining the magnitude of the stem reserves contributing to the grain yield; namely the ability of the stem to store photosynthate and the efficiency of remobilization and transport to the grain of the stored carbohydrates reserves. Stem reserves are important carbon sources for grain filling in crop plants, especially under adverse growing conditions (Ehdaie et al 2006, Fenta et al 2012). In the present study, WS treatments constrained current photosynthate accumulation in the stem (Fig 2), but stimulated the apparent remobilization of the stem reserves to the grain (Fig.…”

“…In cereals, grain-filling rate depends on the availability of current photoassimilate supply and the capacity of remobilizing carbohydrate reserves from the vegetative organs to the grains. The latter has been considered one major compensation mechanism to maintain a steady rate of grain filling when the current photosynthate supply is limited under abiotic stresses (Ehdaie et al 2006). Studies have shown that the remobilized reserves could contribute to 5-20 % of the final grain yield under non-stress conditions, while it might rise to 40-60 % under stressful growing conditions (Blum 1998).…”

“…As in wheat, the stem comprises the peduncle, the penult internodes and the rest internodes. These internodes do not functioning equally in storing and remobilizing of the reserves (Ehdaie et al 2006), being that the lower ones usually play more important roles in supplying carbohydrate reserves to the grain than the upper ones (Ehdaie et al 2006).…”