Selection for root morphological traits improves the growth of grafted bell pepper
Plant breeding programs seldom explicitly consider root traits in selecting high-performance lines. With increased emphasis on resource use efficiency in horticulture, there is a need to identify root traits that are linked to nutrient capture. Grafting could provide a basis for identifying beneficial root traits to be included in breeding programs. Research was conducted to investigate the relationship between root traits and biomass of bell pepper (Capsicum annuum) using a standard commercial cultivar ('Warlock') as a scion over 11 rootstocks of wild pepper (Capsicum chinense), while self-grafted 'Warlock' was used as a control. After 5 weeks of growth in rhizoboxes, the plants were harvested to determine the biomass and root traits (total length, surface area, volume and average diameter). Effect of rootstocks resulted in above-ground biomass differences of -12 to +65% relative to the control, indicating that some rootstocks of the wild accessions were able to exploit more soil resources for a greater above-ground growth. Analysis of root images indicated that eight accessions produced significantly larger root surface area and volume, with a larger biomass allocation to shoots compared with the control. Shoot biomass was significantly correlated with root length (r2=0.484), root surface area (r2=0.424) and root volume (r2=0.355). These correlations showed that some rootstocks are capable of producing larger above-ground biomass with a relatively smaller photosynthate investment in root growth. These results indicate that the selection of wild accessions as rootstock has the potential to improve the root system of bell pepper for a greater above-ground biomass.
Mohd Nor, N.H., Fujinuma, R., Menzies, N.W., Harper, S. and McGrath, D. (2016). Selection for root morphological traits improves the growth of grafted bell pepper. Acta Hortic. 1127, 211-216
resource use efficiency, rootstock, grafting, root traits, above-ground biomass