A method of measuring the water potential of stored potato tubers (Solanum tuberosum L.) was needed to investigate the relationship of bacterial soft rot in tubers to water potential. Pressure chamber measurements, while useful for tubers with functional stolons, cannot be made on stored tubers. Measurements could be made on excised tissue pieces in a hygrometer chamber and with hygrometers imp...

With an elevator installed in a 90-meter tall Sequoiadendron to collect the samples, xylem pressure potential measurements were made approximately every 15 meters along 60 meters of the tree's height. The measured gradient was about -0.8 bar per 10 meters of height, i.e., less than the hydrostatic gradient. Correction of the xylem pressure potential data by calibration against a thermocouple ps...

PREMISE OF THE STUDY California experienced severe drought between 2012 and 2016. During this period, we compared seasonal changes in tissue-water relations among eight fern species in the Santa Monica Mountains of southern California to elucidate differential mechanisms of drought survival and physiological performance during extreme water deficits. METHODS We monitored seasonal changes in w...

Temporal and spatial variations in the water status of walnut trees (Juglans regia L.) and the soil in which they were growing were traced by analyzing the differences in hydrogen isotopes during spring and summer in a 7-year-old walnut stand. Walnut root dynamics were measured in both dry and wet seasons. Walnut roots were mainly distributed in the upper soil (0-30 cm depth), with around 60% o...

water stress effects on winter and spring leaves anatomy were investigated in experiments conducted at the experimental field of sb university of kerman using five wheat cultivars.xylem and phloem elements diameter and mesophyll, bundle sheath and epidermal cells area were measured in transverse sections prepared from middle parts of the leaves. results showed that significant difference exists...

Xylem hydraulic conductance varies in response to changes in sap solute content, and in particular of potassium (K(+)) ion concentration. This phenomenon, known as the 'ionic effect', is enhanced in embolized stems, where it can compensate for cavitation-induced loss of hydraulic conductance. Previous studies have shown that in well-watered laurel plants (Laurus nobilis L.), potassium concentra...

After the discovery of ion-mediated changes in xylem hydraulic resistance a few years ago, a number of research papers were published that related ion-mediated flow changes in the xylem to various aspects of whole plant functioning and evolutionary diversification of vascular cells. Ion-mediated changes in xylem hydraulic resistance are commonly quantified as the percentile change in hydraulic ...

Comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on xylem pH, ABA, and ionic concentrations of tomato (Lycopersicon esculentum L.) plants were investigated in two split-root pot experiments. Results showed that PRI plants had similar or significantly higher xylem pH, which was increased by 0.2 units relative to DI plants. Nitrate and total ionic concentratio...

At the onset of ripening, some fleshy fruits shift the dominant water import pathway from the xylem to the phloem, but the cause for the decline in xylem inflow remains obscure. This study found that xylem-mobile dye movement into grape berries decreased despite transient increases in berry growth and transpiration during early ripening, whereas outward dye movement continued unless the roots w...

A physical analysis of water movement through elongating soybean (Glycine max L. Merr.) hypocotyls was made to determine why significant water potentials persist in growing tissues even though the external water potentials were zero and transpiration is virtually zero. The analysis was based on a water transport theory modified for growth and assumed that water for growing cells would move thro...