Abstract:
To investigate the root anatomy and hydraulic conductivity of wheat cultivars,
including Shiraz, Bahar, Pishtaz, Sistan, and Yavaros, a series of controlled environment
(growth chamber) experiments were hydroponically conducted at University College of
Dublin (UCD), Ireland in 2010. Bahar, Pishtaz and Sistan cultivars were employed as
tolerant to drought and Shiraz and Yavaros as sensitive. Twelve plants from each wheat
cultivar in three replications were compared in a completely randomized design. Seminal
roots had four to five cortical cell layers, and typically one large central metaxylem and
5±1 (in Bahar) to 7±1 (in Yavaros) smaller and circularly arranged peripheral metaxylem
vessels. Stellar cells were less lignified in adventitious roots, as compared with seminal
roots, and mature xylem vessels of seminal roots of Shiraz and Yavaros cultivars had
more lignified walls compared to the other cultivars of the 18 day old plants. Lateral roots
of Shiraz cultivar showed the most lignified walls compared to the other cultivars. The
highest root hydraulic conductivity in seminal roots was observed in Bahar with the
lowest surface area and lignified cell walls. Type of cultivar had also a noticeable effect on
flow rate of seminal roots and varied from 2.81 in Shiraz to 3.76×10-10 m s-1 in Bahar
cultivar. With respect to flow rate and osmotic driving force of seminal and adventitious
roots, Bahar and Sistan cultivars had the highest hydraulic conductivity. It was concluded
that at the early growth stage of wheat cultivars (3
rd leaf stage), root anatomical
structures of Bahar and Sistan were more efficient in water uptake and this might be
attributed to the less lignified cell wall of the peripheral and central metaxylem zones of
the roots in these cultivars.
Keywords: Flow rate, Lateral roots, Osmotic driving force, Peripheral metaxylem.
