INFLUENCE OF LEAF POSITION, MEDIUM TYPE AND BORON ACCUMULATION ON LEAF TIPBURN IN Chlorophytum comosum (THUNB) JAQUES "VARIEGATUM".

During two successive seasons, complete randomized design experiments
were conducted under natural conditions in plastic house on one-year-old
Chlorophytum comosum (Thunb) Jaques "Variegatum" plants to:
(1) study the effect of Ca (as calcium hydroxide), P (as treble superphosphate, 48%
P₂0s), F (as sodium fluoride) and B (as boric acid, 17% B) on the leaftipburn in
Chlorophytum. The rates were 0, 2, 4 and 6 g/l. of medium for Ca and P; 0, 3, 6 and 9
mgll. F in solution and 0,5,10 and 15 mgll. Bin solution. Plants were grown ina
mixture of 1 soil : 1 peat : 1 perlite (by volume) or in sphagnum peat moss. Ca
significantly raised the pH and reduced the leaf tipburn area in both media. P
significantly reduced the pH of the mixture and raised it in sphagnum peat, but did not
reflect a consistent effect on the leaf tipburn. F significantly raised the pH both media
in the 1 st season and did not affect the leaf tipburn. At 10 and 15 mgll. B the pH of
both media was significantly reduced, while the burning of the tip on the oldest leaves
was significantly developed with increasing B rates. The concentrations of the tested
elements in the leaf tissues showed an increasing trend with increasing elements in
the medium. As B accumulation increased in the oldest leaves, the tipburn area
increased. Leaf tissues of every treatment contained Na which may be related to the
lamina tipburn.
(2) study the B distribution through the plant foliage using plants grown in
sandy culture treated with (a) a complete Hoagland and Arnon' solution; (b) a second
without B or (c) a third containing 20x the recommended amount of B. With increasing
B amount in the solution the B leaf tissue content and the tip burn area on the oldest
leaves were increased. The uppermost leaves did. not exhibit lamina tipburn. B
accumulation in the oldest leaves was more than that in the uppermost ones. B
distribution in the various parts of the oldest leaves was not uniform and most of B
accumulated in the distal parts, which resulted in the appearance of tipburn on it.