Quantifying the contribution of bent shoots to plant photosynthesis and biomass production of flower shoots in rose (Rosa hybrida) using a functional–structural plant model

Abstract

Background and Aims The success of using bent shoots in cut-rose (Rosa hybrida) production to improve flower shoot quality has been attributed to bent shoots capturing more light and thus providing more assimilates for flower shoot growth. We aimed at quantifying this contribution of photosynthesis by bent shoots to flower shoot growth. Methods Rose plants were grown with four upright flower shoots and with no, one or three bent shoots per plant. Plant architectural traits, leaf photosynthetic parameters and organ dry weight were measured. A functional–structural plant (FSP) model of rose was used to calculate photosynthesis of upright shoots and bent shoots separately, taking into account the heterogeneous canopy structure of these plants. Key Results Bent shoots contributed to 43–53 % of total assimilated CO2 by the plant. Plant photosynthesis increased by 73 and 117 % in plants with, respectively, one and three bent shoots compared with plants without bent shoots. Upright shoot photosynthesis was not significantly affected by the presence of bent shoots. However, upright shoot dry weight increased by 35 and 59 % in plants with, respectively, one and three bent shoots compared with plants without bent shoots. The increased upright shoot dry weight was entirely due to the contribution of extra photosynthesis by bent shoots, as this was the only source that could induce differences in upright shoot growth apart from their own photosynthesis. At least 47–51 % of the photosynthesis by bent shoots was translocated to upright shoots to support their biomass increase. Conclusions Based on model simulations, we conclude that the positive effect of shoot bending on flower shoot growth and quality in cut-rose production system can almost entirely be attributed to assimilate supply from bent shoots. FSP modelling is a useful tool to quantify the contributions of photosynthesis by different parts of heterogeneous canopies.

Variation of Photosynthetic Induction in Major Horticultural Crops Is Mostly Driven by Differences in Stomatal Traits

“…Although the harvested product for horticultural crops can be very different from staple food crops, e.g., fresh flowers, fruits, and flavor additives, biomass production (thus photosynthesis) remains the basis for high yield and good product quality. For example, flower number was positively correlated with plant dry weight in chrysanthemum ( Carvalho and Heuvelink, 2003 ), and extra assimilates contributed by the canopy improved the stem quality of cut-rose ( Zhang et al, 2020 ). Therefore, increasing photosynthesis is important for optimizing horticultural crop production, especially where growth in most crops can be assumed to be a source rather than sink limited for most of the production season ( Marcelis, 1994 ; Li et al, 2015 ).…”

Disentangling the effects of photosynthetically active radiation and red to far-red ratio on plant photosynthesis under canopy shading: a simulation study using a functional–structural plant model

“…The size of the phytomer was determined by actual plant architectural measurements, with the assumption that the phytomer size between every second phytomer can be linearly interpolated. The assumption of linear interpolation of organ size was validated using data measured on the same cultivar in another experiment (the experiment is described in Zhang et al ., 2019 ; validation results are given in Supplementary Data Fig. S4 ).…”

“…Phyllotaxis was obtained from measurements on the same cultivar in another experiment (=192°) and was fixed for all simulated plants (the experiment is described in Zhang et al ., 2019 ). Leaf insertion angle was assumed to follow a normal distribution according to the average leaf angle and standard deviation of all replicates in each treatments ( Zhang et al ., 2019 ). Leaflet number of each compound leaf on the plant was obtained from the actual plant architectural measurements ( Fig.…”

Light from below matters: Quantifying the consequences of responses to far‐red light reflected upwards for plant performance in heterogeneous canopies

“…All leaves were assumed to have the same quantum efficiency. Photosynthetic parameters of rose leaves (i.e., values of A 0,upright , A 0,bent , k , dark respiration rate and quantum efficiency) were obtained from another experiment with the same rose cultivar (Zhang, van Westreenen, Evers, Anten, & Marcelis, 2019; Figure S5) and can be found in Method S1.…”