Seedling growth and water relations of three Cedrela species sourced from five provenances: response to simulated rainfall reductions

Abstract

The effects of different simulated rainfall regimes on water relations, growth, and biomass production and allocation of five provenances of Cedrela fissilis, C. saltensis and C. balansae were assessed in a pot-grown seedling experiment in greenhouse under uncontrolled conditions. Four simulated rainfall regimes were applied: 600 mm year -1 (severe water deficit), 800 mm year -1 (mild water deficit), 1,000 mm year -1 (mild wet), and 1,200 mm year -1 (well-watered) used as control. Provenances were compared in terms of water relations (midday leaf water potential, W md and relative water content, RWC), growth (root, shoot and leaf length, neck diameter), growth rate (shoot-and neck growth rate, SGR and NGR), biomass production (root, shoot and leaf dry weight), and biomass allocation (root:shoot ratio, RSR). Multivariate analyses revealed that water relations differed significantly under all simulated rainfall treatments by means of several variables throughout time. Effects of species 9 treatment, and provenance nested within species 9 treatment interactions significantly were important. SGR and RSR also were important to explain differences in W md and RWC between treatments and provenances. Broadly C. balansae and C. saltensis provenances seem to display a better performance than C. fissilis provenances under severe water deficit only. However, despite differences between provenances, it was not possible to clearly separate them according to their origin, based on water relations and growth performance. Even though the results of this study performed on pot-grown seedlings are based on relatively few observations and require additional confirmation, they allow an opportunity for speculation on the factors that are related to intraspecific variations that are likely to occur during the growth of seedlings from different geographical sites in field condition.

Comparative studies of the response of larch and birch seedlings from two origins to water deficit

“…It indicated that Prince Rupprecht's larch is more affected by water deficit than eastern larch, and white birch is more affected than paper birch. The result conflicts with our second hypothesis, as well as the conclusions of Otieno et al (2005) and Ruiz et al (2013).…”

“…The morphological changes of the four species to drought were consistent with the general responses of other species. Leaf shedding of birch seedlings in low-water environments has * difference at P < 0.05, ** difference at P < 0.01 been shown to occur to limit evaporative losses when seedlings can no longer maintain a positive carbon balance (Levesque et al 2013;Ruiz et al 2013;Mantovani et al 2014). During drier periods, reduction in available soil water results in closure of stomata and decrease of stomatal conductance C i to limit evaporative losses.…”

“…Tree responses to water deficit that are out of their natural environments depend on their native habitats (Otieno et al 2005;Ruiz et al 2013;Jansons et al 2016). It has been observed that in a common water stress environment, seedlings originating from drier areas tend to display a better performance than those from wetter areas (Ruiz et al 2013;Levesque et al 2013). In our study, seed origin of eastern larch and paper birch was of mesic conditions with a mean annual precipitation sum of 1144 mm, being distributed rather uniformly over the year (Fig.…”

“…Forests have globally and regionally suffered from drought and heat events (Kozyr 2014;Anenkhonov et al 2015). These include pine and oak species in Mediterranean regions (Ruiz et al, 2013), larch forests and pine forests of the lower forest belt in Southern Transbaikalia, Russia (Kozyr 2014), and coniferous forests in South Korea (Kim et al 2017). The common causal factors in these examples are elevated temperatures and/or water stress, raising the possibility that the world's forests are increasingly responding to ongoing warming and drying.…”

Does Cedrela always form annual rings? Testing ring periodicity across South America using radiocarbon dating

“…This shows that identifying the trigger factor for growth rhythms in tropical trees is not always straightforward, as different tropical tree species respond to different cues (Borchert et al 2015), and there could also be differences in response between sub-populations of the same species (e.g. Ruiz et al 2013;Stubblebine et al 1978).…”