Reduced height (Rht) and photoperiod insensitivity (Ppd) allele associations with establishment and early growth of wheat in contrasting production systems

Abstract

Addisu, M., Snape, J. W., Simmonds, J. R., Gooding, M. J. (2009). Reduced height (Rht) and photoperiod insensitivity (Ppd) allele associations with establishment and early growth of wheat in contrasting production systems. Euphytica, 166 (2), 249-267.Near isogenic lines (NILs) varying for genes for reduced height (Rht) and photoperiod insensitivity (Ppd-D1a) in a cv. Mercia background (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht8c + Ppd-D1a, Rht-D1c, Rht12) were compared at one field site but within contrasting (?organic? vs. ?conventional?) rotational and agronomic contexts, in each of 3 years. In the final year, further NILs (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht-B1b + Rht-D1b, Rht-D1b + Rht-B1c) in both Maris Huntsman and Maris Widgeon backgrounds were added together with 64 lines of a doubled haploid (DH) population [Savannah (Rht-D1b) ? Renesansa (Rht-8c + Ppd-D1a)]. Assessments included laboratory tests of germination and coleoptile length, and various field measurements of crop growth between emergence and pre jointing [plant population, tillering, leaf length, ground cover (GC), interception of photosynthetically active radiation (PAR), crop dry matter (DM) and nitrogen accumulation (N), far red: red reflectance ratio (FR:R), crop height, and weed dry matter]. All of the dwarfing alleles except Rht12 in the Mercia background and Rht8c in the DHs were associated with reduced coleoptile length. Most of the dwarfing alleles (depending on background) reduced seed viability. Severe dwarfing alleles (Rht-B1c, Rht-D1c and Rht12) were routinely associated with fewer plant numbers and reduced early crop growth (GC, PAR, DM, N, FR:R), and in 1 year, increased weed DM. In the Mercia background and the DHs the semi-dwarfing allele Rht-D1b was also sometimes associated with reductions in early crop growth; no such negative effects were associated with the marker for Rht8c. When significant interactions between cropping system and genotype did occur it was because differences between lines were more exaggerated in the organic system than in the conventional system. Ppd-D1a was associated positively with plant numbers surviving the winter and early crop growth (GC, FR:R, DM, N, PAR, height), and was the most significant locus in a QTL analysis. We conclude that, within these environmental and system contexts, genes moderating development are likely to be more important in influencing early resource capture than using Rht8c as an alternative semi-dwarfing gene to Rht-D1b.Peer reviewe

Coleoptile length and plant height of modern tall and semi-dwarf European winter wheat varieties

“…Distribution of accessions' coleoptile length was similar to that found in many other experiments [2,18,22,23]. Most of the accessions differed significantly in coleoptile length.…”

“…Longer coleoptiles provide greater seedling early vigour, competition with weeds, crop establishment, more efficient soil water use, and better penetration through soil crust [16,17]. European varieties possessing genes Rht-B1b and Rht-D1b were characterized by reduced seed viability and lower early resource capture in combination with lower competitiveness with weeds [18]. Varieties possessing longer coleoptiles generally have faster, more even emergence and improved early vigour [11].…”

“…The varieties possessing Rht8 also possess photoperiod insensitivity gene Ppd. This germplasm should be investigated more comprehensively for frost resistance to be used for breeding purposes in Northern and Western European countries [18]. Moreover, such early flowering and ripening germplasm is hardly suitable for the above mentioned region due to lower yielding capacity [3].…”

“…Most of the recent European semi-dwarf winter wheat varieties possess genes Rht-D1 and Rht-B1 and possibly short coleoptiles [18,22]. On the other hand, there are some semi-dwarf varieties without Rht genes [3].…”

Impact of Growth Habit and Architecture Genes on Adaptation and Performance of Bread Wheat

“…Similar results were also reported by Wilhelm et al [80], confirming the significant effect of Rht-B1 on flowering time and suggested a possibility of genes controlling plant height to also affect flowering time. However, other studies report that earliness is often associated with reduced height and potentially reduced resource capture, therefore, reduced yield [42,83]. This suggested negative correlation between earliness and yield remains a challenge in wheat breeding programs, posing a need to modify flowering time to suit local climatic conditions while maintaining or even increasing yield potential.…”