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as havlng slgnltlcantly hlgher level of resistance lo fall atmyworm feeding as compared to
non-regenerated and NuceptlMe parenl. From laboratory studles on larval leedlng on
meredlc dlet contalnlng drled sorghum follage, significant reductions In larval welght were
detected for two R, llnes whlch suggests the involvement of antibiosis. Free cholce tests
revealed a significant non-preference for the R, lines that had shown the greatest adverse
effect on fall armyworm growth in the developmental studies. Some of the other reports on
increased resistance to specHlc pathogens by selecting variants on screening populations d
regenerated plants are the development of sugarcane varieties with enhanced resistance to
eyespot disease, fiji disease and downy mildew (Heinz et al. 1977), and, increased tolerance
to Verticillium albo-afrumin alfalfa which was associated with Increased ploldy level (Latunde-
Dada and Lucas, 1983) where, lt was hypothesized that increclsed resistance was due to gene
dosage enect.
Selection for salt tolerance however has met with little success. Nabors et ai. (1980) ldentltied
heritable tolerance that resulted in tobacco plants tolerant d 3.3% sodium chloride (NaCI).
McCoy (19870) observed in vMo NaCl tolerance at 85 mM and 170 mM. However all
genotypes exhibiting NaCl tolerance were observed to be NaCl sensitive at the whole plant
level. M, mafina exhibited whole plant NaCl tolerance (0.6% NaCi) but was NaCl senritive at
the in vMo level as the other NaCl senritive species. A potentld NaCI tolerant germplasm
source was therefore identified in M, marina In his later study, McCoy (1987b) selected NaCl
tolerant cell lines by a step-up selection procedure where cell llnes tolerant to 0.5% NaCl were
subrsquently sdectd at 1% NaCI, which retained tolerance alter tansfnr to contd medium.
Extensive somaclonal vadatlon was observed In plants regenerated horn these NaCi tolemt
cell llnw. 44.7% were extreme dwark (5 cm); unbalanced polypkid chmmotorne rots wHh
one vatant having 166 chrmornes were observed. The Iro2ynu paltams of @ants hum
NaCl toiuant cell liner were also extenslv.ly attend. In vlho NaCl tolome wor maintained