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- Author or Editor: Dean M. Krauskopf x
Abstract
Forcing azalea (Rhododendron sp. cvs. Redwing, Mission Bells and Gloria were subjected to sufficient and low levels of N, K, and Ca, and the difference in concentration of these nutrients was measured and termed “differential”. Immature, recently mature, and old leaves were sampled periodically from current shoots during development. Ca differential was not related to sample position. N differential was exhibited in a similar manner but was best expressed in older leaf tissue during late growth. The magnitude of the K differential was related to both sample position and sample date; the largest expression occurred in young leaf tissue during early growth and on older leaf tissue during late shoot development. The best single sample position for foliar analysis of these nutrients was the most recently mature leaves on current shoots.
Abstract
Analysis of deficiency symptoms and foliar analyses of canopy leaves (youngest leaves 5 cm of wider) of Rieger elatior begonias (Begonia X hiemalis Fotsch cv. Schwabenland Red) indicated that the minimum critical levels for K, Mg, and B lie in the ranges of 0.93 to 0.95%, 0.22 to 0.25%, and 13.0 to 14.0 ppm, respectively.
Abstract
Symptoms for 7 nutrient deficiencies were established for elatior begonia ‘Schwabenland Red’ (Begonia X hiemalis Fotsch.). These are summarized in the form of a key as follows:
a. Chlorosis is a dominant symptom.
b. Chlorosis interveinal.
c. Interveinal chlorosis on older leaves followed by light tan necrotic spots within chlorotic areas which expand until leaf dies........................................................................................................................Mg
cc. Interveinal chlorosis on younger leaves.....................................................................................................Fe
bb. Chlorosis not interveinal.
c. Lower leaves uniformly yellow then purplish yellow and finally necrotic.................i.....................N
cc. Margins of canopy leaves yellow, then murky green-brown, and finally necrotic; all symptoms spread toward the leaf center......................................................................................................................Ca
aa. Chlorosis not a dominant symptom.
b. Necrosis begins along the margin of lower leaves and progresses inward....................................................K
bb. Plants stunted but normal green..........................................................................................................................P
bbb. Rust color, striations and cracks develop on young leaf petioles and peduncles perpendicular to their axes; internodes shortened and lateral shoots prolific; young leaves brittle crinkled around rust color spots which turn necrotic; chlorosis and necrosis spreading inward from the margin of young leaves...B
Abstract
Optimum N and K rates were established for ‘Schwabenland Red’ Rieger begonia for weekly fertilization and for application with each watering. Weekly application of 400 ppm N or more and 150 ppm or less resulted in undesirable plant size reduction regardless of K level; 200 ppm was marginal and 250 and 300 ppm N were best. Weekly applications of 60 to 200 ppm K were best and equal when applied with 250 ppm N while levels of 250 ppm K and greater caused smaller final plant size. The best rates of N for application with each watering were 100 and 150 ppm; 75 ppm and lower and 200 ppm and higher had deleterious effects. K levels from 50 to 125 ppm were best for application with every watering while levels of 150 ppm and greater were undesirable.