Effects of juice pH and potassium on juice and wine quality, and regulation of potassium in grapevines through rootstocks (Vitis): a short review

In warm irrigated regions of Australia (such as Sunraysia), pH of grape juice often tends to be high (e.g. > 3.8). A high juice pH is undesirable for the production of quality wines as it results in wines of low quality for example, reduced colour stability and poor taste. Such a high juice pH is typically associated with a high concentration of K in the juice, depending on  the scion, rootstock and location. Potassium is an essential nutrient and plant genotypes, including grapevines, differ in the accumulation of K in plant and/or plant parts. This difference in the accumulation of K by genotypes can be exploited to manipulate the concentration and content of K in plants, berries in particular for example, through selection and use of low K accumulating rootstocks to overcome the high pH affects. This paper briefly reviews the effects of juice pH and on juice and wine quality, and the role and effect of rootstocks in the regulation of K in grapevine. This will provide a basic knowledge about the current research and key future research needed for the maintenance of acceptable quality of grape juice and wine through use of rootstocks.

Effects of juice pH and potassium on juice and wine quality, and regulation of potassium in grapevines through rootstocks (Vitis): A short review

In warm irrigated regions of Australia (such as Sunraysia), pH of grape juice often tends to be high (e.g. > 3.8). A high juice pH is undesirable for the production of quality wines as it results in wines of low quality for example, reduced colour stability and poor taste. Such a high juice pH is typically associated with a high concentration of K in the juice, depending on the scion, rootstock and location. Potassium is an essential nutrient and plant genotypes, including grapevines, differ in the accumulation of K in plant and/or plant parts. This difference in the accumulation of K by genotypes can be exploited to manipulate the concentration and content of K in plants, berries in particular for example, through selection and use of low K accumulating rootstocks to overcome the high pH affects. This paper briefly reviews the effects of juice pH and on juice and wine quality, and the role and effect of rootstocks in the regulation of K in grapevine. This will provide a basic knowledge about the current research and key future research needed for the maintenance of acceptable quality of grape juice and wine through use of rootstocks

Uptake, transport, accumulation and retranslocation of potassium in grapevine rootstocks (Vitis)

The concentration and content of potassium (K) within grapevine can be regulated by selective use of rootstocks. However, the mechanisms by which rootstocks differ in the accumulation of K in the shoot of grapevine are not well understood. Therefore, the current study addresses these issues. Ungrafted rootstocks 140 Ruggeri (140 R) and 101-14 Millardet de Grasset (101-14) were exposed to K tracer rubidium (Rb) in a glasshouse, for 4 hours through roots to study uptake and transport of Rb from roots to shoot, and for 24 hours through leaf to study downward transport of Rb, in each case assessed up to 48 hours following exposure to Rb. Transpiration rates and root traits were also measured. Results showed similar total Rb uptake and similar downward transport of Rb between the two rootstocks but lower accumulation of Rb in the shoot and lower shoot/roots Rb concentration (as a result of higher retention of Rb in roots), in 140 R than that in 101-14. Transpiration rates and total root length (but not total root surface area) remained similar between two rootstocks. The study shows that short term differences in the accumulation of K in roots and shoot between rootstocks are due to differences in the transport of K from roots to the shoot, rather than by differences in net uptake or retranslocation of K. In addition, such differences were not affected by transpiration rates. The results highlight that accumulation of K in shoot of grapevine rootstocks is regulated mainly by roots

Accumulation of potassium in grapevine rootstocks (Vitis) grafted to ‘Shiraz’ as affected by growth, root-traits and transpiration

The concentration of potassium (K) in scions can be controlled by rootstocks (Vitis). However, differences between rootstocks in the accumulation of K and mechanisms of regulation of K, when rootstocks are grafted to a scion, are not clearly understood. Therefore, the current study addresses these issues. Rootstocks Freedom, Schwarzmann, Ramsey, 1103 Paulsen, 110 Richter, 140 Ruggeri and 101-14 were grafted with ‘Shiraz’ and grown in sand for 56 days in a glasshouse, with daily watering using solutions containing 3 mM K. At day 56, Freedom had highest total K uptake. Freedom and 101-14 had the highest and 140 Ruggeri the lowest concentration of K respectively, in shoot and roots. Accumulation of K in grapevine is affected by the interaction between rootstock and scion, with total K uptake increasing with total root length, total root surface area and percentage of roots in small diameter class (< 0.5 mm). Accumulation of K in the whole grapevine or in the shoot was not affected by either shoot/roots dry weight or transpiration, but was positively related to concentration of K (but not Na) in xylem. The current study highlights the positive impact of root based factors, specifically root traits and root pressure than other (e.g. shoot/roots dry weight, transpiration) in the accumulation of K in ‘Shiraz’ grapevines when assessed as grafted vines on a range of rootstocks. This knowledge will be important in selecting the new rootstocks for appropriate K uptake or accumulation.

Uptake, transport, accumulation and retranslocation of potassium in grapevine rootstocks (Vitis)

The concentration and content of potassium (K) within grapevine can be regulated by selective use of rootstocks. However, the mechanisms by which rootstocks differ in the accumulation of K in the shoot of grapevine are not well understood. Therefore, the current study addresses these issues. Ungrafted rootstocks 140 Ruggeri (140 R) and 101-14 Millardet de Grasset (101-14) were exposed to K tracer rubidium (Rb) in a glasshouse, for 4 hours through roots to study uptake and transport of Rb from roots to shoot, and for 24 hours through leaf to study downward transport of Rb, in each case assessed up to 48 hours following exposure to Rb. Transpiration rates and root traits were also measured. Results showed similar total Rb uptake and similar downward transport of Rb between the two rootstocks but lower accumulation of Rb in the shoot and lower shoot/roots Rb concentration (as a result of higher retention of Rb in roots), in 140 R than that in 101-14. Transpiration rates and total root length (but not total root surface area) remained similar between two rootstocks. The study shows that short term differences in the accumulation of K in roots and shoot between rootstocks are due to differences in the transport of K from roots to the shoot, rather than by differences in net uptake or retranslocation of K. In addition, such differences were not affected by transpiration rates. The results highlight that accumulation of K in shoot of grapevine rootstocks is regulated mainly by roots. Key words: Cation, nutrient, root, shoot, translocation, transpiration

Regulation of berry quality parameters in 'Shiraz' grapevines through rootstocks (Vitis)

The concentration of potassium (K) and pH in juice of grapevines is influenced by rootstocks (Vitis). However, the performance of rootstocks with respect to berry quality parameters and inter-relationships among berry quality parameters are not well understood. The current study addresses these issues. Berry and leaf samples at harvest maturity were collected from mature field-grown 'Shiraz' grapevines grafted with each of the rootstocks Dogridge, Freedom, Ramsey, 1103 Paulsen and 140 Ruggeri. Concentrations of K in juice and petiole and pH in juice were each highest for Dogridge and Freedom, but lowest for 140 Ruggeri and 1103 Paulsen. High concentration of K in juice was related to high concentrations of malic acid and TSS but low tartaric acid/malic acid ratio. In this study, lower concentrations of K in juice and in turn pH in juice of 'Shiraz' grapevines were maintained through rootstocks such as 140 Ruggeri and 1103 Paulsen that also show lower concentrations of K in petiole and TSS in juice, and higher tartaric/malic acid concentration ratio in juice at maturity. Selective use of these rootstocks in turn helps to produce quality grape juice and wine.

Valuing seasonal climate forecasts in the northern Australia beef industry

Seasonal climate forecasts (SCFs) provide opportunities for pastoralists to align production decisions to climatic conditions, as SCFs offer economic value by increasing certainty about future climatic states at decision-making time. Insufficient evidence about the economic value of SCFs was identified as a major factor limiting adoption of SCFs in Australia and abroad. This study examines the value of SCFs to beef production system management in northern Australia by adopting a theoretical probabilistic climate forecast system. Stocking rate decisions in October, before the onset of the wet season, were identified by industry as a key climate sensitive decision. The analysis considered SCF value across economic drivers (steer price in October) and environmental drivers (October pasture availability). A range in forecast value was found (0-$14/head) dependent on pasture availability, beef price and SCF skill. Skilful forecasts of future climate conditions offered little value with medium or high pasture availability, as in these circumstances, pastures were rarely over-utilised. In contrast, low pasture availability provided conditions for alternative optimal stocking rates and for SCFs to be valuable. Optimal stocking rates under low pasture availability varied the most with climate state (i.e. wet or dry), indicating that producers have more to gain from a skilful SCF at these times. Although the level of pasture availability in October was the major determinant of stocking rate decisions, beef price settings were also found to be important. This analysis provides insights into the potential value of SCFs to extensive beef enterprises and can be used by pastoralists to evaluate the cost-benefit of using a SCF in annual management

Fire resistance of bearing walls in light steel frame (LSF) structures including various insulation filler materials by finite element method

Using prefabricated structure in lightweight construction is the new method in both industry and civil engineering. Lightweight Steel Frame (LSF) becomes more valuable in the construction industry due to low cost, low weight, high speed of installation and resistance to environmental conditions. Cold-rolled form lightweight load-bearing wall is consisting of a thin sheet of steel with C-shaped sections (STUD), thermal insulation filler and cover sheets (Plaster Board). However, regardless of existing plasterboard protection the thin-walled steel sections heat up quickly and lose their strength under fire conditions. The main goal of the current study is an evaluation of thermal capacity and bearing strength of lightweight walls in terms of cellulosic fire condition analytically. The variable parameters are insulation filler materials (polystyrene, polystyrene concrete) and axial load. The Abaqus finite element software was used for modeling and analyzing of fire loads. Lightweight concrete fillers increase the axial bearing capacity of walls sustainably and polystyrene filler improved the fire resistance of walls