PJB-2022-381
INCIDENCE OF ALTERNARIA LEAF SPOT OF OKRA IN PESHAWAR AND NOWSHERA DISTRICTS OF KHYBER PUKHTUNKHWA AND EVALUATION OF OKRA GENOTYPES FOR RESISTANCE TO THE DISEASE
jehan sher
Abstract
ABSTRACT
The present survey was conducted during the year 2021 to record the Alternaria leaf spot disease incidence on Okra plants in different locations of Peshawar and Nowshera districts of Khyber Pakhtunkhwa, to collect infected leaf samples from these locations for isolation of pathogen (Alternaria alternata) and to compare the mycelial growth of on Potato Dextrose Agar (PDA) medium. Overall, significantly (P= 0.00) higher disease incidence of 79.39 % was recorded in district Nowshera as compared with district Peshawar (57.57 %). Among the three locations of district Nowshera, the significantly (P= 0.00) highest disease incidence of 85.95 % was observed at Khushmaqam followed by Garrimomind (78.45 %) while the lowest disease incidence (73.78 %) was noticed at Baanda. Similarly, among three locations of district Peshawar, the highest disease incidence of (70.50 %) was observed at Charpareza followed by Muslimabad (56.12 %) while the lowest disease incidence (46.11 %) was recorded at Palosai. Among the 18 isolates from the infected leaf samples, isolate alt 6 from Khushmaqam district Nowshera was found to be the most vigorous giving colony diameter of (7.80 cm) after two weeks of incubation at 25 Cͦ followed by alt 1 (7.55 cm) from Garrimomind of the same district. while alt 14 from Muslimabad district Peshawar registered the poorest growth (2.21 cm). It was noted that isolate vigor on PDA medium was associated with level of disease incidence in the field. Among the fifteen Okra genotypes evaluated for resistance to the disease under natural field conditions at ARI, Ternab Peshawar, OK 01 was found to be the most resistant giving the least value of AUDPC (37.25) followed OK Green (162.80) while the genotype Arkoanamika was observed to be the most succeptible with AUDPC value of 252.05. The Genotypes OK 01 and OK Green also gave the highest No. of pods (296 and 274 respectively) and yield (1620.0and 1223.3 g/plot respectively), while the lowest means for these parameters were recorded in the genotype Arkoanamika (71.0 and 246 g/plot respectively). In conclusion, a great deal of difference occurred among the A. alternata isolates, The molecular basis of which needs to be determined. Similarly, significant differences existed among the okra genotypes regarding disease resistance as well as growth and yield parameters. Although no okra genotypes performed to be resistant to alternaria alternata, yet we found genotypes OK 01 and OK Green to be resistant to this disease. We recommend the cultivation of these genotypes in area affected more with this disease.
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