Reaction of CMU Var 12 at different growth stages to Diplodia macrospora Earle inoculations
2001
Franje, N.S. | Franje, H.E.
The study was conducted to answer which growth stage of CMU Var 12 is vulnerable to the Diplodia macrospora Earle. Two separate sets of experiments were conducted. The first set accomodated the three-way cross, GSI 40 M, to represent one source of hybrid bearing high resistance to the Diplodia disease. The other set was planted to CMU Var 12, an open-pollinated variety, to test its potentials against the disease D. macrospora Earle. The inoculation of D. macrospora was done at whorl stage, 25% and 75% flowering, at bluster, milk and soft dough stages, respectively. Findings showed that no significant effect of inoculating the disease at different stages was observed on the hybrid GSI 40 M and OPV CMU Var 12 based on its ear diameter and ear lengths. The identity of the cultivars to exhibit comparable ear diameters and ear lengths to that of the control plants showed the degree of resistance it can offer against D.macrospora. Plants inoculated at whorl stage had the highest number of infected ears. The percent infected ears had a mean of 14.05% for CMU Var 12 and a lower mean value of 10.76% for GSI 40M. GSI 40M had a higher degree of resistance showing a lower number of Diplodia infected ears ranging from as low as 2.5% to as high as 10.76%. The OPV CMU Var 12 recorded a range of 6.72-14.05% infection of the D. macrospora. Results showed that neither OPV CMU Var 12 nor GSI 40 M was influenced by inoculation at any stage of growth based on its percent shelling recovery and adjusted yields. Percent yield loss of OPV CMU Var 12 was highest at whorl stage (T2) while GSI 40 M exhibited a higher percent yield loss when inoculated with Diplodia at 25% silking stage. It showed that the GSI 40 M tolerated the inoculum at an earlier infection while OPV CMU Var 12 was susceptible at whorl and 25% silking stage against the infection of Diplodia
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