S A I Nihad
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
A Ara
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
M M Rashid
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
M A I Hasan
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
M A I Khan
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
M A Latif
Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazip
Bacterial blight, Correlation, Disease screening, Genetic divergence analysis, Morphological traits, Rice genotypes.
RRI, Los Banos, Philippines, and Bangladesh Rice Research Institute (BRRI), Gazipur-1701, Bangladesh.
Variety and Species
A total of 94 genotypes were collected from IRRI, Los Banos, Philippines, and Bangladesh Rice Research Institute (BRRI), Gazipur-1701, Bangladesh. Plants were grownup in the experimental plot of Plant Pathology Division for bacterial blight screening. Genotypes were grown in the seedbed and 25 days aged plants were planted in the plot by implementing randomized complete block design (RCBD) with three replications. Isolation and purification of pathogens Bacterial blight-infected plants were obtained from rice field for isolation of the pathogen. Infected leaves were cut into small pieces (5mm infected tissue and 5mm of adjacent healthy tissue) and placed in 70% ethanol for 10 seconds, after that the leaves were washed through sterilized water and immersed in 300 µl sterilized water for 15 minutes. A loop was dipped into the water and streaked on PSA (peptone 1.2%, sucrose 1.2%, agar 2%) plates followed by incubation for 3 to 4 days at 30oC for bacterial colony development. The yellow colonies were selected and purified on fresh PSA plates with a sterilized wire loop. The pathogenicity was confirmed according to Koch's postulates on a susceptible variety.
Bacterial culture preparation and disease scoring After dilution of the bacterial inoculum by distilled water, the concentration was adjusted to 3.3×108 colony forming units per milliliter (cfu/mL), which is a suitable concentration for genetic Xoo infection in the host. Bacterial culture suspension was inoculated in the plants by clipping methods. Studied genotypes were inoculated at the booting stage. The scissors were dipped in the inoculum and one-fourth of top 3- 4 leaves were clipped by the scissors. After 21 days of inoculation, disease severity and incidence were scored based on following IRRI Standard Evaluation System (IRRI-SES) (IRRI, 2013). Resistant, 1-5% of diseased leaf area (Score 1), moderately resistant 6-12% (Score 3), moderately susceptible 12-25% (Score 5), susceptible 26-50% (Score 7), highly susceptible >50% (Score 9). Later, moderately susceptible, susceptible and highly susceptible were merged into one group as susceptible. However, other groups (resistant and moderately resistant) remain the same as before. Morphological characters such as plant height (PHT, cm), number of tillers per hill (NTH-1 , no), number of effective tiller per hill (ETH-1 , no), days to flowering (DF, no), days to maturity (DM, no), Panicle length (PL, cm), number of filled spikelet per panicle (NFSP-1 , no), number of unfilled spikelet per panicle (UFSP-1 ), total number of spikelets per panicle (TNSP-1 ), 1000 grain weight (TGW) and yield per hill measured from each replication plot of the respective genotypes. Descriptive statistics of morphological parameters of the genotypes were calculated by Microsoft excel version 2016. To measure the associations among the 11 morphological characters Pearson's correlation coefficient was done by SPSS software version 20. Euclidean distance of the 94 genotypes was measured based on morphological data by using NTSYSpc version 2.1 (Rohlf, 1998). Moreover, unweighted pair group methods of arithmetic mean (UPGMA) algorithm and SAHN clustering were applied to determine the relationship among the genotypes. The principal component analysis (PCA) of studied rice lines were revealed by EIGEN and PROJ modules of NTSYS-pc. Moreover, the principal coordinate analysis was done by following the manual instruction of the same software.
Bangladesh Rice J. 24 (1): 73-84, 2020
Journal