STUDIES ON IRON CHLOROSIS OF SUGAR-CANE (SACCHARUM-OFFICINARUM L) AT METAHARA, ETHIOPIA - SOIL AND PLANT CHARACTERIZATION AND EFFICIENCY OFDIFFERENT IRON SOURCES
A. Dametie et al., STUDIES ON IRON CHLOROSIS OF SUGAR-CANE (SACCHARUM-OFFICINARUM L) AT METAHARA, ETHIOPIA - SOIL AND PLANT CHARACTERIZATION AND EFFICIENCY OFDIFFERENT IRON SOURCES, Journal of agronomy and crop science, 175(5), 1995, pp. 317-324
In order to understand the nature and causes of chlorosis at Metahara
Sugar Estate (8 degrees 53'N and 39 degrees 52'E) in Ethiopia, soil pr
ofile samples were collected from a ratoon field that exhibited chloro
sis. From the same site, the first ratoon sugar cane leaf blades (+3)
were sampled on the basis of the degree of chlorosis, and thus categor
ised into green, medium green, medium yellow and yellow. Soil sample a
nalysis indicated that DTPA-extractable Fe, Mn and Cu were adequate fo
r normal plant growth in spite of an increase in CaCO3 content. Moreov
er, the chlorotic leaves contained higher iron content than the green
ones. Consequently, it is concluded that iron chlorosis of sugar cane
at Metahara could be due to physiological inactivation of iron in soil
s and the plant. A field experiment was also conducted using sugar can
e variety CO-449 in order to select the most effective iron source to
control iron chlorosis of the plant. The plots received the treatments
of FeSO4, EDDHA and DTPA at three different levels each as foliar spr
ays. The untreated plots were used as control. The chemicals were appl
ied on the first ratoon 3 weeks after harvest, and repeated a week aft
er the first spray. Twenty millable canes from the middle two rows wer
e sampled at 12 months for yield and juice quality determinations. Iro
n sulphate spray at 15 kg ha(-1) increased cane length and commercial
cane sugar by 33 and 44 % over the control, respectively. The highest
cane yield was secured by spraying DTPA at 1.80 kg ha(-1) even though
its recoverable sugar percentage was low. Not all sources of iron impr
oved juice quality. Since FeSO4 at 15 kg ha(-1) was equally effective
as the 30 kg ha(-1) FeSO4 applications, the need to consider other tha
n the currently used rate in the Estate is timely and is very importan
t.