A Study of the Root System of Barley

Abstract

SUMMARYRelationships between the number, length, surface area, volume and dry weight of the root members of two varieties of barley {Hordeum vulgare L. vars Maris Badger and Proctor) were examined over the first 4 weeks of growth in water culture. Plants given a complete nutrient supply were compared with plants deficient in potassium or phosphorus.Although there were large effects of age, variety and nutrition on all the root dimensions, relationships between the dimensions varied comparatively little. In consequence, effects of age, variety and nutrition on the rate of nutrient uptake per unit of root were qualitatively similar whichever dimension ofthe root system was considered.It is shown by reference to descriptions of root systems published elsewhere that constancy in relationships between root dimensions occurs in solid media also. This property of root systems, which appears to result quite straightforwardly from the contrasting morphological characteristics of root axes and laterals, may help to simplify some aspects of the study of nutrient absorption by roots.

A Growth Analysis of the Young Sorghum Root System

“…Despite the rapid rate of increase in total length, the average root length I (total length/total No.) remained roughly constant, as has been observed in other species (Hackett 1971). The values of I were about 75 % higher than the average of those for barley (May et at.…”

“…The values of I were about 75 % higher than the average of those for barley (May et at. 1965;Hackett 1969Hackett , 1971. The value of d was smaller at day 9 than later, but the agreement between the values at the last two harvests suggested that d was stabilizing, as has also been observed in other species (Hackett 1971).…”

“…1965;Hackett 1969Hackett , 1971. The value of d was smaller at day 9 than later, but the agreement between the values at the last two harvests suggested that d was stabilizing, as has also been observed in other species (Hackett 1971). Because d in the sorghum plants was of the order of 0·2 mm, the total root length occupied only 0·2 and 4·4 cm 3 at days 9 and 17 respectively.…”

“…It was notable that there were 11 ·4 m of root on day 9 and 143·0 m by day 17 (0·32 ill m-l day-l). These values make a striking comparison with ones for barley [4 m at day 14, 50 m at day 28, 0·19 m m-1 day-l (Hackett 1968(Hackett ,1969] and for wheat [8 m at day 14, 30 m at day 21, 0·19 m m-1 day-l (Passioura 1972)]. Despite the rapid rate of increase in total length, the average root length I (total length/total No.)…”

“…The sample was spread on a small portion of Marsh's grid, and the diameter of pieces intersecting the lines was recorded by use of a microscope. In this wayan average diameter (d) was obtained which was weighted according to the length of each type of root member present (Hackett 1968). Except for the lowest depths, where insufficient material was available, 40 determinations of diameter were made for each depth from each replicate cylinder.…”