Assessment of Rosa spp. Plant Architecture in the Field

Rosaspp. is one of the most important ornamental crops globally. Currently the annual value of garden roses in the USA is approximately $400 million and there is a need for better adapted roses. In Texas, heat stress has been reported as a predominant abiotic stress to roses which can affect plant architecture, flower intensity, and eventually plant health. The plant architecture is a crucial trait in rose breeding as it affects the ornamental appearance and flower intensity. The objective of this study is to develop a standard protocol to quantify how environmental conditions, especially heat stress, influence the architecture of roses. Four diploid populations were created by crossing heat tolerant and sensitive parents. Ten seedlings in each population were selected to evaluate in the field and under greenhouse conditions. Six components were measured on each primary, secondary and tertiary branch: branching angle, number of dormant nodes, number of nodes on vegetative part, length of vegetative part, length of reproductive part, and number of flowers on the terminal inflorescence. Additionally, the inflorescence structure type was recorded on each individual plant. The variation among these traits within the segregating populations was characterized.