Published online by Cambridge University Press: 27 March 2009
Twenty-one two-row and 19 six-row barley cultivars, originating from the major barley growing areas, were compared in a duplicated experiment conducted under controlled environment conditions. Plants were grown in sand and supplied nitrate at two concentrations.
Number of leaves on the mainstem and leaf emergence rate both varied widely but there were no consistent differences between two- and six-row cultivars. The low nitrogen treatment led to significant reductions in number of leaves and emergence rates. As a result of these opposing effects the time of appearance of the flag leaf was not affected by treatment. The number of leaves unfolded was a linear function of time where nitrogen was supplied at high concentration but for plants supplied with low nitrogen, appearance of the third and fourth leaves was considerably delayed. Cultivars producing fewer leaves on the mainstem also showed faster leaf emergence and both these factors contributed to the earliness of a cultivar.
Low nitrogen treatments reduced number of spikelets per ear in both two-row and six-row barleys; this treatment also reduced the number of grain filled, although mean grain weight was not affected. Faster leaf emergence rates were associated with fewer spikelets per ear in both nitrogen treatments.
Since they are based on a relatively large number of cultivars it is likely that these results are general for barley. The importance of further detailed examination of apical development is indicated.