Morphological and anatomical adaptations of cocksfoot leaves grown under different fluctuating light regimes in New Zealand.

PERI P.L.; MOOT D.J.; LUCAS R.J.; JARVIS P.

Orlando, Florida, USA

Congreso; 1st World Congress of Agroforestry, Session VI Tree Domestication and Management; 2004

University of Florida

The effect of different fluctuating light regimes (24, 43, 58 and 100% transmissivity) on leaf morphology and anatomy adaptations of cocksfoot (Dactylis glomerata L.) was measured in the Lincoln University Silvopastoral experiment (New Zealand). The duration of alternating periods of full sunlight (1900 µmol m-2 s-1 PPFD at midday) to severe shade (130 µmol m-2 s-1 PPFD) ranged from 45 to 180 minutes. The length of the youngest fully expanded leaf and pseudo-stem height increased by up to 33% and the leaf width declined up to 22% with decreasing light intensity. This elongation was primarily related to enlargement of epidermal cell length as a response to reduced proportions of red (660 nm) to far-red (730 nm) wavelengths (R:FR) from 1.32 in full sun light to 0.54 in severe shade. Cocksfoot leaves grown in fluctuating light regimes were thinner than full sunlight leaves due mainly to a reduction in mesophyll cell size (bigger spongy and higher palisade cells) and bundle area and to a lesser extent in the number of cells. As a consequence of anatomical and morphological adaptations to different light regimes, cocksfoot plants increased the specific leaf area (SLA) from 27 to 38 m2 kg-1 DM with decreasing light intensity. The mean canopy leaf angle decreased from 68º for plants grown in full sunlight to 59º under 24% transmissivity as a result of their longer and thinner leaves combined with a lower number and smaller size of bundles. The wide range of leaf morphology and anatomy dimensions emphasised the cocksfoot leaf plasticity under different light regimes.