Abscission of Leaves in Tea
Tea is an evergreen plant. An evergreen is a tree or plant that doesn't shed its leaves in the winter, but stays green all year. In tea whether the plant is under freely growing condition or under plucking, leaves shedding occur and it is related to the activity of the growing apices. In a freely growing tea shoot, only two consecutive flushes below the terminal bud of possess leaves until a new flush occurs. When a new flush occurs, irrespective of whether the new flush is leafy or cataphyllary, abscission of leaves from the lower most of the two flushes takes place. The leaves on the first flush of a shoot drop when the terminal bud grows for the third leafy or cataphyllary flush and this order of leaf abscission continues for the remaining flushes. For this reason a shoot becomes completely leafless when two cataphyllary flushes are produced on the top of a leafy flush. A cataphyllary flush is a flush produced by a shoot in which instead of normal leaves, cataphylls are unfolded. Thus, depending on the activity of the terminal bud, leaves on the shoot may or may not shed at a particular time of the year. This means that life span of leaves on freely growing shoots of tea is independent of chronological time but is determined by the activity of the growing apices.
In tea bushes under plucking, shoots arising from the pruned bush frame are tipped at a certain height to accelerate the growth of shoots from the lower leaf axils and subsequently the young tender shoots are plucked for manufacture of tea. These tipping and plucking operations releases the lower portions of the shoots from apical dominance. Absence of apical activity, therefore, prevents abscission of leaves and stimulates growth of axillary buds. However, the tipped shoots can retain their leaves for a maximum of 18 months.
