Shoot orientation affects vessel size, shoot hydraulic conductivity and shoot growth rate in Vitis vinifera L.

Abstract

Vitis vinifera L. plants were grown in containers and each plant's single shoot was orientated upwards or downwards. Some plants were trained first upwards, then downwards, then again upwards (N-shaped plants). Vegetative growth was reduced in plants trained downwards compared to that in upward and N-shaped plants. Shoot growth rate slowed in downward shoot portions, but only after the apex had grown downwards for at least 10 internodes. Shoot hydraulic conductivity k h , measured after elimination of xylem embolisms, was lower in downward than in upward plants. In N-shaped plants k h was higher in the upward-growing shoot portions, and lower in the central, downward-growing portion. Shoot-and leafspecific conductivities were also lower in downward than in upward shoot portions. Xylem cross-sectional area and xylem structure (number of wedges, number of vessels per unit xylem area) differed little in the three orientations. In contrast, vessel diameter and the sum of vessel cross-sectional areas were significantly smaller in downward than in upward shoot portions. These differences could explain the reduction in conductivity observed in the downwardorientated shoot portions. The measurements taken on Nshaped plants showed that the decreases in k h and in vessel size were a result of shoot orientation, not shoot bending.

Grapevine Xylem Development, Architecture, and Function

“…2). They also are higher in their stem hydraulic conductivity (Lovisolo and Schubert 1998;Schubert et al 1999). These changes are consistent with the patterns in grapevine vessel development described above, whereby vessels take several weeks to become functional and different cohorts of vessels are active during different times of the season.…”

“…Most species show an increase in both vessel length and width with increasing stem diameter (reviewed in ) and, consistent with this general trend, grapevine vessel dimensions vary considerably with stem diameter and sample age (discussed below and shown in Fig. 5.10; Lovisolo and Schubert 1998;Schubert et al 1999). Thus, especially in older samples or in wide diameter stems, grapevine xylem may contain very wide (approximately 300 μm diameter) and long (~8 m) vessels (Zimmermann and Jeje 1981).…”

“…Stems grown earlier in the growing season contain vessels that are wider in diameter compared to those produced later in the growing season ( Fig. 5.10; Lovisolo and Schubert 1998;Schubert et al 1999). This pattern is particularly evident when only the widest vessels within a cross section are examined (Fig.…”

Physiological responses and production of 'Syrah' vines as a function of training systems

“…Furthermore, the greater trunk height in GDC system (1.90 m) as compared to VSP (1.0 m) and also the differences in branch orientation could have contributed to hinder water transport to the grapevine canopy. Schubert et al (1999) showed that shoot hydraulic conductivity is negatively affected by downward branch orientation in contrast with upward growing (Deloire et al, 2004), the photosynthesis was unaffected as shown by other authors for grapevine (Souza et al, 2005b) and other crop species (Fereres and Soriano, 2007). The differences between seasons of CO 2 assimilation rates were probably due to weather conditions (temperatures) during gas exchange measurements, as explained above for results of leaf water potential.…”

Vessel development and the importance of lateral flow in water transport within developing bundles of current-year shoots of grapevine (Vitis vinifera L.)

“…For this purpose, we used the current-year shoots of grapevine (Vitis vinifera L.) and we followed in detail the course of vessel differentiation and maturation along the developing bundles of the stem axis. Grapevine provides an ideal experimental plant for these investigations, because it has relatively wide and also long vessels (Ewers et al 1990;Schubert et al 1999;Thorne et al 2006). Living vessel elements were identified using dye movement method.…”