Archive for September, 2014

PhytoSim was used to study crop load effects in peach trees

Monday, September 15th, 2014

On August 22th 2014 a paper was published which used a model, implemented in PhytoSim, to assess the effects of crop load on stem diameter variations and fruit growth of peach trees.

Reference:

De Swaef T., Mellisho C.D., Baert A., De Schepper V., Torrecillas A., Conejero W. and Steppe K. (2014) Model-assisted evaluation of crop load effects on stem diameter variations and fruit growth in peach. Trees.

http://link.springer.com/article/10.1007/s00468-014-1069-z

Abstract:

Stem diameter (D stem) variations have extensively been applied in optimisation strategies for plant-based irrigation scheduling in fruit trees. Two D stem derived water status indicators, maximum daily shrinkage (MDS) and daily growth rate (DGR), are however influenced by other factors such as crop load, making it difficult to unambiguously use these indicators in practical irrigation applications. Furthermore, crop load influences the growth of individual fruits, because of competition for assimilates. This paper aims to explain the effect of crop load on DGR, MDS and individual fruit growth in peach using a water and carbon transport model that includes simulation of stem diameter variations. This modelling approach enabled to relate differences in crop load to differences in xylem and phloem water potential components. As such, crop load effects on DGR were attributed to effects on the stem phloem turgor pressure. The effect of crop load on MDS could be explained by the plant water status, the phloem carbon concentration and the elasticity of the tissue. The influence on fruit growth could predominantly be explained by the effect on the early fruit growth stages.

Facebook Twitter Linkedin Email

PhytoSim used to study stem diameter variation patterns in different mangrove species

Tuesday, September 9th, 2014

On February 16th 2014 a paper was published which used a model, implemented in PhytoSim, to study stem diameter variation patterns in different mangrove species.

Reference:

Vandegehuchte M.W., Guyot A., Hubeau M., De Swaef T., Lockington D.A. and Steppe K. (2014). Modelling reveals endogenous osmotic adaptation of storage tissuewater potential as an important driver determining different stem diameter variation patterns in the mangrove species Avicennia marina and Rhizophora stylosa. Annals of Botany, 114(4), 667-676.
http://aob.oxfordjournals.org/content/114/4/667.abstract.html?etoc

Abstract:

Background Stem diameter variations are mainly determined by the radial water transport between xylem and storage tissues. This radial transport results from the water potential difference between these tissues, which is influenced by both hydraulic and carbon related processes. Measurements have shown that when subjected to the same environmental conditions, the co-occurring mangrove species Avicennia marina and Rhizophora stylosa unexpectedly show a totally different pattern in daily stem diameter variation.

Methods Using in situ measurements of stem diameter variation, stem water potential and sap flow, a mechanistic flow and storage model based on the cohesion–tension theory was applied to assess the differences in osmotic storage water potential between Avicennia marina and Rhizophora stylosa.

Key results Both species, subjected to the same environmental conditions, showed a resembling daily pattern in simulated osmotic storage water potential. However, the osmotic storage water potential ofR. stylosa started to decrease slightly after that of A. marina in the morning and increased again slightly later in the evening. This small shift in osmotic storage water potential likely underlaid the marked differences in daily stem diameter variation pattern between the two species.

Conclusions The results show that in addition to environmental dynamics, endogenous changes in the osmotic storage water potential must be taken into account in order to accurately predict stem diameter variations, and hence growth.

Facebook Twitter Linkedin Email