actiefblad

Actiefblad is a term used in Dutch plant physiology and horticulture to refer to a leaf that actively carries out photosynthesis and growth. It is used to distinguish leaves that are actively functioning from leaves that are senescent or dormant, which have reduced photosynthetic capacity. In greenhouse and field production, actiefblad typically describes leaves on the current growth flush that contribute most to carbohydrate production and to supplying assimilates for developing shoots, flowers, or fruits. The leaves most commonly classified as actiefblad are young, fully expanded, and well illuminated, with high chlorophyll content and relatively high stomatal conductance. As leaves age or deteriorate under poor light, water, or nutrient conditions, their contribution diminishes and they may be considered inactief or senescent.

Measurement and assessment of actiefblad can be indirect, through observations of leaf color and turgidity, or more objectively with tools such as SPAD meters for chlorophyll content and gas exchange measurements to estimate photosynthetic rate. In practical horticulture, management practices aim to maximize the proportion of actiefbladeren, for example by maintaining adequate nitrogen nutrition, optimizing irrigation, and arranging light distribution, as well as by pruning to promote a new flush of actively functioning leaves.

The concept is closely tied to general plant physiology, including photosynthesis, leaf age, and senescence. While the term actiefblad is common in Dutch agricultural literature, its exact usage can vary and it may be described with more formal terms in different contexts.