EFFECTS OF BARLEY INTRACOLEOPTILAR INTERNODE LENGTH AND EFFECTIVE XYLEM RADIUS ON WATER USE AND DRY MATTER PRODUCTION

A series of experiments was conducted to determine if altering the length and effective xylem radius (EXR) of the intracoleoptilar internode (ICI) of barley (Hordeum vulgare L.) would alter water use and increase yields. Uniculm barley genotype F73-1 with long ICI conserved soil water from seeding to maturity, on a very restricted water supply. However, plants with long ICI did not produce significantly more (P > 0.1) dry matter or grain despite using less water per gram of dry matter produced. Plants of cultivar Abee, which have short ICI, used more water than plants with long ICI, under sample available soil moisture. Over a 3-h period, measured water loss for short ICI plants was, on average, 2.32 g vs. 1.37 g for long ICI plants. Progeny selected from the cross Abee/TR450 with genetically long ICI and small EXR, and those with short ICI and large EXR did not differ in water use or in amount of dry matter produced. When 16 barley cultivars were sown on a light-textured soil at 4 and 7 cm seeding depths, there was no cultivar by seeding depth interaction in any of four field experiments conducted. The cultivar Abee, with a long ICI and small EXR, did not produce higher yields. While increasing the length of the ICI of a given genotype and reducing its EXR may be of value under extreme conditions where plants are growing on stored subsoil moisture, this trait appears to be of little use in improving grain yields on drought-prone sandy soils in the eastern prairie region of western Canada.Key words: Barley, Hordeum vulgare, intracoleoptilar internode, effective xylem radius, drought tolerance