Components of leaf elongation rate and their relationship to specific leaf area in contrasting grasses

In grasses the leaf growth zone is the main site of shoot growth where anatomical and chemical characteristics of leaves originate. Yet, there is insufficient information to generalize as to whether the leaf growth zone reflects habitat characteristics, whether leaf growth traits are regularly interrelated, and whether they coincide with characteristics of mature leaves. Here the contribution of both length of the leaf growth zone (region where cell division and expansion occurs) and relative elemental growth rate to the variability in leaf elongation rate (LER) were examined in eight grass species from habitats with different soil fertility. Further, we examined the relationship of the above traits with specific leaf area (SLA) and its components. Growth zone length differed significantly among species (P<0.05) and it was the trait contributing the most to LER. Using LER and derived components it was possible to classify seven out of eight species into two groups related to soil fertility. Leaf elongation rate exhibited a positive correlation to SLA and a negative correlation to leaf dry matter content. A significant relationship existed between size of the growth zone and leaf dry matter content. The results suggest that the leaf growth zone is a critically important leaf trait that explains inherent differences in LER and other plant characteristics of grass species.