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- Title
Root system size response of bzh semi-dwarf oilseed rape hybrids to different nitrogen levels in the field.
- Authors
Schierholt, Antje; Tietz, Tina; Bienert, Gerd Patrick; Gertz, Andreas; Miersch, Sebastian; Becker, Heiko C
- Abstract
Background and Aims In oilseed rape (Brassica napus) semi-dwarf hybrid varieties from crosses between bzh dwarf and normal-type lines are of increasing interest. They have improved nitrogen (N) uptake, N-utilization and N-use efficiency compared to normal types. This study aimed to elucidate whether these N-related effects can be explained by the bzh shoot growth-type alone or also by differences in root traits. Methods Root system size was measured using root electrical capacitance (EC) in field trials with two N levels in two sets of genotypes segregating for the bzh -locus: (1) 108 doubled haploid (DH) test hybrids in two seasons, 2010–2012, and (2) 16 near-isogenic hybrids in the 2016–17 season. Quantitative trait loci (QTL) for root EC were estimated in DH test hybrids. Seedling root architecture parameters were monitored in vitro. Key Results In vitro root growth showed a higher root: shoot ratio in bzh semi-dwarf hybrids. Root EC in field trials was higher at high N supply than at zero N fertilization. In most trials semi-dwarf hybrids had higher EC than normal-type hybrids, but they reduced root EC in response to N limitation more than normal types. Root EC was more heritable at the end of flowering (h 2 = 0.73) than at the beginning of flowering (h 2 = 0.36) in near-isogenic hybrids and had a lower heritability in trials of DH test hybrids (h 2 = 0.27). A QTL for root EC in the genomic region of the bzh -locus on linkage group A06 was significant at zero N fertilization. Conclusions Root EC proved to be a meaningful method in oilseed rape breeding programmes targeting root system size. The greater reduction of semi-dwarf root EC compared to the normal type under low N supply with simultaneous increase in N efficiency implies that in roots it is not a question of 'the more the merrier' and that the bzh root system reacts highly economically when N is scarce.
- Subjects
ROOT growth; NITROGEN; NITROGEN content of plants; WEYL groups; SIZE; BRASSICA; ELECTRIC capacity; HETEROSIS in plants
- Publication
Annals of Botany, 2019, Vol 124, Issue 6, p891
- ISSN
0305-7364
- Publication type
Article
- DOI
10.1093/aob/mcy197