| Summary: | Photoperiod, vernalization, and plant height controlling genes are major developmental genes in wheat that govern environmental adaptation and hence, knowledge on the interaction effects among different alleles of these genes is crucial in breeding cultivars for target environments. The interaction effects among these genes were studied in nineteen Australian advanced lines from diverse germplasm pools and four commercial checks. Diagnostic markers for the <i>Vrn-A1</i> locus revealed the presence of the spring allele <i>Vrn-A1a</i> in 10 lines and <i>Vrn-A1c</i> in one line. The dominant alleles of <i>Vrn-B1a</i> and <i>Vrn-D1a</i> were identified in 19 and 8 lines, respectively. The most common photoperiod-insensitive allele of <i>Ppd-D1a</i> was identified in 19 lines and three and four copy photoperiod-insensitive alleles (<i>Ppd-B1a</i> and <i>Ppd-B1c</i>) were present in five and one lines, respectively. All the lines were photoperiod-sensitive for the <i>Ppd-A1</i> locus. All lines were semi-dwarf, having either of the two dwarfing alleles; 14 lines had the <i>Rht-B1b (Rht-1)</i> and the remaining had the <i>Rht-D1b (Rht-2)</i> dwarfing allele. The presence of the photoperiod-insensitive allele <i>Ppd-D1a</i> along with one or two spring alleles at the <i>Vrn1</i> loci resulted in an earlier heading and better yield. Dwarfing genes were found to modify the heading time—the <i>Rht-D1b</i> allele advanced heading by three days and also showed superior effects on yield-contributing traits, indicating its beneficial role in yield under rain-fed conditions along with an appropriate combination of photoperiod and vernalization alleles. This study also identified the adaptability value of these allelic combinations for higher grain yield and protein content across the different the water-limited environments.
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