Page 7 - International Journal of Horticulture

International Journal of Horticulture 2014, Vol.4, No.11, 53-57
http://ijh.biopublisher.ca
56
resistant lines had limited the infection. All F1’s
showed stoma number ranging between (11.33 to
12.33 upper surface) and (36.44 to 41.40 lower
surface) which was more or less similar to that of
resistant parents. Unlikely, that the stomata number
alone could account for the difference in rust
resistance among the genotypes. Possibly structural
features of stomata might be involved in triggering
appresorium formation. These observations and
inference were similar to the findings of Groth and
Urs (1982), Shaik (1985), Edington et al. (1994a) and
Aghora (1999).
In the view of above reports, stomatal structural
aspects in relation to resistance were studied. Stomatal
length was maximum in susceptible parents ranging
0.031 m to 0.035 m. while resistant parents and
hybrids recorded stomatal length of 0.021 m to 0.025
m which was considerably shorter. Even in case of
stomatal width, the susceptible parents had wider
stomata (0.018 m to 0.022 m) when compared to
resistant parents and hybrids (0.008 m to 0.013 m).
The stomatal pore length was found be to short in
resistant parents and hybrids (0.013 m to 0.017 m)
conversely, lengthy stomatal pore was recorded in
susceptible genotypes (0.049 m to 0.060 m).
Similar trend was observed for stomatal pore width
also. Thus, broader pore size was recorded in
susceptible genotypes ranging between 0.011 m to
0.018 m and very thin pores were found in resistant
and F1’s (0.001 m to 0.006 m).
The 2 value indicated that association existed
between all the physiological traits studied with
AUDPC and the correlation coefficient confirmed the
findings that the positive association existed and it
was highly significant. High positive significant
association was observed between AUDPC and upper
stomatal number (0.9330), lower stomatal number
(0.9840), stomatal length (0.9320), stomatal width
(0.9680), stomatal pore length (0.9970) and pore
width (0.9630). The results further confirmed that
lesser stomata, small size stomata and stomatal pore
play a vital role in restricting the entry of pathogen.
These results were in conformity with the works of
Groth and Urs (1982), Shaik (1985), Edington et al.
(1994a) and Aghora (1999).
Similar to the association of AUDPC with the various
physiological traits imparting resistance, PDI and rate
of infection also having association with all
components. Correlation analysis indicated that PDI
and rate of infection had positive and highly
significant association with all components, further
confirmed the role of lesser stomata, small size
stomata and stomatal pore size in imparting resistance.
These results were in conformity with the works of
Groth and Urs (1982), Shaik (1985), Edington et al.
(1994a) and Aghora (1999).
Conclusion
Among the genotypes screened against rust under
natural and artificial epiphytotic conditions, all the
resistant parents and crosses did not show disease
symptom and all three susceptible parents showed
disease severity. The results indicated that the
physiological basis of resistance, the structural
features of stomata, like small stomatal pore size,
narrow stoma and reduced number of stomata are
highly related to impart rust resistance in french bean
cultivars.
Materials and Methods
Material for present study consisted of five parents
and six F 1 combinations of the crosses, IIHRPB -1 Х
IC -525236, IIHRPB- 2X IC-525236 and IIHRPB-7×
IC -525236 and IIHRPB- 1×Arka Anoop, IIHRPB- 2X
Arka Anoop, and IIHRPB- 7×Arka Anoop which were
laid out in randomized block design with three
replications. Experiment was done at experimental
block of Division of Vegetable Crops, IIHR during
October, 2012.
The leaves of all five parents and their F1’s viz.,
IIHRPB -1×IC-525236 , IIHRPB- 2×IC-525236 and
IIHRPB -7×IC-525236 and×IIHRPB-1×Arka Anoop,
IIHRPB -2×Arka Anoop, and IIHRPB-7×Arka Anoop
at flowering stage were used for the studies.
Stomata count:
Fevicol method was employed to record mean stomata
number. Fevicol was smeared on both the surfaces of
leaf to form a thin film. After five minutes fevicol
layer was peeled off and mounted on clean slide and
observed under microscope. Number of stomata for
lower surface was recorded at 10×40 magnifications
and expressed in terms of number of stomata per
0.009 sq mm area of leaf surface.
Stomatal size: