Mutagenesis—A Potential Approach for Crop Improvement - Crop Improvement: New Approaches and Modern Techniques - page 159

Fig. 4.3 A beam with suf-
ficient energy penetrates a
plantlet and/or plant tissue
with rather low and uniform
LET and it will then drasti-
cally increase towards the
end of the track that is known
as the Bragg peak (BP).
(Modified from Kazama et al.
2008 )
Fig. 4.4 Conceptual diagram
of LET
and thus is described as more biologically effective and mutagenic than X-rays and
gamma rays. A wider mutation spectrum and less collateral physiological damage
(i.e. effect on plant survival and growth) is commonly reported for ion beam radia-
tion as compared to other mutagens, which is considered an important advantage.
In China, 23 new rice and wheat mutant varieties have been bred using ion beam
technology and released for large scale commercial production (more than 1 mil-
lion ha per annum). The wheat variety 'Wanmai 54' displayed excellent resistance
to head scab disease and rust disease and recorded the highest yield in the national
new wheat variety yield trial (2003-2007), with yield increases over control variety
of 7-10.6 %. In Japan, ion beam technology has been used for generating mutants
for a vast number of plant species by various researchers; for example, a consortium
of more than 90 user groups was established to utilize the ion beam technology