Abstract
SUMMARYUnderstanding the effect of genetic factors controlling flowering time is essential to fine-tune crop development to each target environment and to maximize yield. A set of 35 durum wheat genotypes of spring growth-habit involving different allelic combinations at Ppd-A1 and Ppd-B1 genes was grown for 2 years at four sites at latitudes ranging from 19°N to 41°N. The emergence-flowering period was reduced from north to south. The frequency in the collection of the insensitive allele GS-105 at Ppd-A1 was greater (34%) than that of allele GS-100 (20%). Genotypes that flowered earlier due to the presence of alleles causing photoperiod insensitivity extended their grain-filling period, but less than the shortening in flowering time. The effect of the allele conferring photoperiod sensitivity at Ppd-A1 was stronger than that at Ppd-B1 (Ppd-A1b > Ppd-B1b). The effect of photoperiod insensitivity alleles was classified as GS-100 > GS-105 > Ppd-B1a. The phenotypic expression of alleles conferring photoperiod insensitivity at Ppd-A1 increased at sites with average day length from emergence to flowering lower than 12 h. An interaction effect was found between Ppd-A1 and Ppd-B1. Differences between allelic combinations in flowering time accounted for c. 66% of the variability induced by the genotype effect, with the remaining 34% being explained by genes controlling earliness per se. The shortest flowering time across sites corresponded to the allelic combination GS-100/Ppd-B1a, which reduced flowering time by 11 days irrespective of the Ppd-A1b/Ppd-B1b combination. The current study marks a further step towards elucidation of the phenotypic expression of genes regulating photoperiod sensitivity and their interaction with the environment.
Highlights
Maximizing plant yield potential in any given environment requires optimizing the use of water, nutrients and radiation, and avoiding negative effects from any type of stress during the vegetative and grain-filling periods
Allele polymorphisms that were identified in bread wheat were not observed in this set of durum wheat (Table 2)
The genotypes were classified into photoperiod sensitivity genes (Ppd)-A1–Ppd-B1 allelic combinations (Table 1)
Summary
Maximizing plant yield potential in any given environment requires optimizing the use of water, nutrients and radiation, and avoiding negative effects from any type of stress during the vegetative and grain-filling periods. This can only be achieved by growing varieties with a flowering time and life-cycle duration suited to the environmental conditions. Wheat flowering time is controlled mainly by three groups of loci, two of which interact with environmental factors, namely photoperiod sensitivity genes (Ppd) and vernalization requirement genes (Vrn) (Distelfeld et al 2009). The third group of loci, controlling ‘narrow-sense earliness’ or ‘earliness per se’ (Eps), act on the developmental rate independently of vernalization and photoperiod (Scarth & Law 1984)
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