Soil porosity changes in orchards with subsurface irrigation: quantification and interpretation

In order to assess the irrigation efficiency under water-limiting conditions, four different treatments of subsurface irrigation of peach trees in a semi-arid Mediterranean climate near Lleida (NE Iberian Peninsula) were tested. The treatments included pressurized air injection, deficit irrigation, full irrigation (as control) and an addition of rice husk around the pipe to improve porosity. Because the latter treatment improved physical conditions and resulted in better tree growth, a micromorphological study was conducted in order to understand the reason for this behaviour. The experiment was carried out in a commercial peach orchard (Prunus persica L.). The soil was a Xeric Torriorthent, with a loam texture, affected by salinity and with low organic matter content. One undisturbed block (30 cm each side) was taken from each treatment, and two vertical thin sections, 5 × 13 cm, including the subsurface pipe, were made. A fluorescent dye was added to the polyester resin to obtain UV light images of the porosity. The pore parameters and the pore size distribution were obtained for each treatment. Strong changes in the pore types of the four treatments are evident in the thin sections. Full and deficit irrigation treatments are characterised by a weakly developed subangular blocky structure, with a vesicular intra-aggregate structure. Deficit irrigation with air injection produced, in its upper part, a structure similar to the full and deficit irrigation treatments. In the surroundings and below the pipe, where the effect of pressurized air was higher, the soil structure is apedal, with vesicles (bubbles), 200 – 500 µm in size. Porosity of the soil modified with rice husk is greater than that of the other three treatments: the 15 – 30 µm porosity fraction is double, and the larger fractions three times that of the other treatments. It contains many oval excrements of mites (probably Oribatidae), 50 – 100 µm in size, associated with moderately decomposed rice husk tissues. We conclude that the modifications around the irrigation pipes that promoted faunal activity are very effective in conveying water to the soil in comparison to that of pressurized air, which only increases vesicular (non connected) porosity.info:eu-repo/semantics/publishedVersio

Differential response to calcium-labelled (44Ca) uptake and allocation in two peach rootstocks in relation to transpiration under in vitro conditions

Calcium-labelled (44Ca) uptake and transport under in vitro GreenTray® temporary immersion bioreactor conditions have been studied related to aeration conditions. For this aim, Rootpac®-20 (RP-20) and Garnem® (G × N) were selected as two main rootstocks used in peach production. Two transpiration conditions, aerated and unaerated, were established for each plant material. 44Ca location, plant development and foliar stomata surface were measured after the in vitro culture period. The results showed that aeration improved Ca transport within the shoot, but it did not enhance Ca uptake by the roots. Regarding plant material, G × N presented a better Ca uptake capacity and concentration. The findings suggest that Ca uptake in the roots is a precise process that is influenced by transpiration. However, it was observed that transpiration and thus the water flux is not the only force promoting Ca uptake by roots. Furthermore, the transport of Ca to the shoot was primarily determined by transpiration, indicating that water flux plays a crucial role in the aboveground movement of Ca. The study also revealed distinct behaviors in Ca uptake and allocation between the different peach rootstocks, emphasizing the importance of considering these factors in the selection process of rootstocks. These findings contribute to our understanding of the mechanisms involved in Ca uptake and transport in peach rootstocks under in vitro conditions. They provide valuable insights for rootstock selection processes and highlight the need for further research in this area

Influence of Regulated Deficit Irrigation on Arbequina’s Crop Yield and EVOOs Quality and Sensory Profile

Regulated deficit irrigation in super-high-density (SHD) olive orchards is a well-known strategy to save water and control plant vigor, without decreasing fruit or oil yield. As there is controversial information about its influence on virgin olive oil quality, a trial was conducted in five SHD olive orchards of Arbequina cultivar in different locations of central, east, north and northeast Spain under full irrigation (FI) and regulated deficit irrigation (RDI) treatments. RDI applied during phase II of fruit growing (40% of total needs) saves more than 20% of water on average, without reductions in olive fruit or extra virgin olive oil (EVOO) yield. No threshold of 3.5 MPa of stem water potential was crossed in any case. RDI modified sterols and the fatty acid profile of EVOOs but not phenols, quality parameters, or the sensory profile. Latitude, altitude, and yearly rainfall have a big impact on some compounds such as campesterol, oleuropein, or margaroleic or linolenic acids.info:eu-repo/semantics/publishedVersio