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<p>Synthetic hexaploid wheat (SHW) has proven to be a valuable genetic resource. When conventionally bred with modern wheat varieties, it presents new potential for improved yield under abiotic stress conditions. In the northwestern plain zones (NWPZ), the reproductive phase of wheat is particularly vulnerable to rising temperatures, known as terminal heat stress. This often causes leaf damage, which then affects the source of individual stems, and studying source-sink dynamics by imposing source-sink manipulations at the individual culm level seems important. Therefore, the present study was conducted on 15 wheat introgression lines (doubled haploids) obtained from two synthetic wheats and two hexaploid wheats (SHW14102 ×BWL4444, SHW14102 ×BWL3531, and SHW3761 &#xa0;× BWL4444). These lines were phenotyped for five yield-related spike traits under late sown condition for two consecutive years 2020–21 and 2021–22. The source-sink ratios were modified by removing alternate spikelet rows at the 50% anthesis stage. This reduced the grain number per ear by 37% and increased the single grain weight by 14%. However, the grain yield per plant was reduced by 9.2% and 1.95% under the sink and source manipulations, respectively. Hence, the source was not a limiting factor for grain yield in introgression lines, whereas the sink appeared to be a limiting factor. In the check cultivars, grain number per ear and grain yield per plant were reduced by 43% and 14% respectively, and single grain weight increased by only 9%. Further, flag leaf removal caused a reduction in plant yield by 3.75% which was more than in introgression lines. This study advocated the strong source-sink relationship in determining the potential introgression lines with superior photosynthetic activity (being derived from accessions having the stay green trait) as compared to check cultivars under terminal heat stress conditions. Further, path coefficient analysis showed that, under terminal heat stress and source–sink manipulations, GNpS remains the key determinant of yield stability. The strong direct effect of GNpS on grain yield suggests that selection for DHs with consistently higher grain number per spike is an effective strategy to enhance sink strength and secure yields under source-stressful conditions. This validates the breeding potential of synthetic hexaploid wheat backgrounds for developing heat-resilient cultivars in NWPZ environment.</p>

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Assessing Source-Sink Dynamics, Genetic Variability, and Determinants of Dry Matter Partitioning in Synthetic-Derived Wheat Introgression Lines Under a Late Sowing Regime

  • 期刊论文

  • 发表日期：

    2026年3月17日

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  • Tavisha Singh,
  • Seema Bedi,
  • Achla Sharma,
  • Satinder Kaur

摘要

Synthetic hexaploid wheat (SHW) has proven to be a valuable genetic resource. When conventionally bred with modern wheat varieties, it presents new potential for improved yield under abiotic stress conditions. In the northwestern plain zones (NWPZ), the reproductive phase of wheat is particularly vulnerable to rising temperatures, known as terminal heat stress. This often causes leaf damage, which then affects the source of individual stems, and studying source-sink dynamics by imposing source-sink manipulations at the individual culm level seems important. Therefore, the present study was conducted on 15 wheat introgression lines (doubled haploids) obtained from two synthetic wheats and two hexaploid wheats (SHW14102 ×BWL4444, SHW14102 ×BWL3531, and SHW3761  × BWL4444). These lines were phenotyped for five yield-related spike traits under late sown condition for two consecutive years 2020–21 and 2021–22. The source-sink ratios were modified by removing alternate spikelet rows at the 50% anthesis stage. This reduced the grain number per ear by 37% and increased the single grain weight by 14%. However, the grain yield per plant was reduced by 9.2% and 1.95% under the sink and source manipulations, respectively. Hence, the source was not a limiting factor for grain yield in introgression lines, whereas the sink appeared to be a limiting factor. In the check cultivars, grain number per ear and grain yield per plant were reduced by 43% and 14% respectively, and single grain weight increased by only 9%. Further, flag leaf removal caused a reduction in plant yield by 3.75% which was more than in introgression lines. This study advocated the strong source-sink relationship in determining the potential introgression lines with superior photosynthetic activity (being derived from accessions having the stay green trait) as compared to check cultivars under terminal heat stress conditions. Further, path coefficient analysis showed that, under terminal heat stress and source–sink manipulations, GNpS remains the key determinant of yield stability. The strong direct effect of GNpS on grain yield suggests that selection for DHs with consistently higher grain number per spike is an effective strategy to enhance sink strength and secure yields under source-stressful conditions. This validates the breeding potential of synthetic hexaploid wheat backgrounds for developing heat-resilient cultivars in NWPZ environment.