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19991
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Subject: Horticulture × Author: Aghora, T S × End date: 1999 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    STUDIES ON MECHANISMS OF RESISTANCE TO RUST AND GENETICS OF QUANTITATIVE CHARACTERS IN SNAP BEAN (Phaseolus vulgaris L.)
    (University of Agricultural Science, Dharwad, 1999) Aghora, T S; Madalageri, M B
    EPIDEMIOLOGICAL COMPONENTS OF PARTIAL RESISTANCE TO RUST, NATURE OF PATHOGENESIS, THE PHYSIOLOGICAL, BIOCHEMICAL AND GENETIC BASIS OF RUST RESISTANCE IN SNAP BEAN {PHASEOLUS VULGARIS L.) WERE INVESTIGATED. ASSOCIATION AND INTER-RELATIONSHIP BETWEEN RUST RESISTANCE AND QUANTITATIVE CHARACTERS, THE COMPONENTS OF GENETIC VARIATION AND GENE ACTION FOR VARIOUS QUANTITATIVE CHARACTERS WERE WORKED OUT. AMONG THE 60 GENOTYPES EVALUATED FOR RUST RESISTANCE UNDER ARTIFICIAL EPIPHYTOTIC CONDITION, 37 GENOTYPES WERE RESISTANT, FIVE LINES VIZ., LLHR-12, 13, 45, 121 AND 161 WERE SLOW RUSTLERS AND 18 WERE SUSCEPTIBLE. SLOW RUSTLERS SHOWED LESS AUDPC, LOW PDI, EXTENDED LATENT PERIOD, FEWER PUSTULES, SMALL PUSTULE SIZE, AND LOW SPORULATION CAPACITY. THE NEGATIVE ASSOCIATION OF AUDPC AND PDI WITH LATENT PERIOD AND POSITIVE AND SIGNIFICANT CORRELATION WITH ALL OTHER COMPONENTS OF PARTIAL RESISTANCE WAS OBSERVED. HISTOPATHOLOGICAL STUDIES REVEALED THAT THE ENTRY OF THE PATHOGEN INTO THE HOST TISSUE WAS THROUGH STOMATA. THE STRUCTURAL FEATURES OF THE STOMATA LIKE SMALL STOMATAL PORE SIZE, NARROW STOMA, AND FEWER STOMATA IMPARTED THE RESISTANCE TO RUST. AMONG THE BIOCHEMICAL COMPONENTS OF RESISTANCE, HIGH CHLOROPHYLL, HIGH PHENOL, AND LOW SUGAR WERE ASSOCIATED WITH RESISTANCE. A PAIR OF DOMINANT GENES CONTROLLED THE RUST RESISTANCE IN IIHR-220 AND KPV-1. THE CROSSES CONTENDER X KPV-1, ARKA KOMAL X IIHR-220, THEIR RECIPROCAL CROSSES AND ARKA KOMAL X KPV-1 WERE HIGH YIELDING WITH RESISTANCE TO RUST. THE ASSOCIATION OF QUANTITATIVE CHARACTERS WITH DISEASE SEVERITY WAS NEGATIVE AND SIGNIFICANT FOR ALL THE TRAITS EXCEPT DAYS TO FIRST FLOWERING AND DAYS TO POD MATURITY. THE MAGNITUDE OF NEGATIVE CORRELATION OF PDI WITH POD YIELD PER PLANT, TOTAL POD NUMBER, TOTAL FLOWERS PER PLANT, SEEDS PER POD AND FLOWERING BRANCHES WERE HIGH. DUPLICATE TYPE OF EPISTASIS FOR PLANT HEIGHT, AND FLOWERING BRANCHES AND COMPLEMENTARY GENE ACTION FOR FLOWERS PER PLANT, PODS PER PLANT AND POD WEIGHT WERE NOTICED. HETEROBELTIOSIS WAS HIGH AND SIGNIFICANT BUT THE GENETIC ADVANCE WAS LOW FOR THE MAJORITY OF THE QUANTITATIVE CHARACTERS INDICATED THE LIMITED POSSIBILITY OF IMPROVING THESE CHARACTERS THROUGH SELECTION. HENCE, IT IS SUGGESTED TO GO FOR BIPARENTAL MATING OF SELECTED PARENTS FOLLOWED BY THE PEDIGREE METHOD OF SELECTION. STUDIES INDICATED THAT THE SELECTION SHOULD BE BASED ON HIGH CHLOROPHYLL, HIGH PHENOL, LOW SUGAR, SMALL AND FEWER STOMATA, LONG LATENT PERIODS, SMALL AND FEWER PUSTULES, LOW PDI, LOW AUDPC AND LOW SPORULATION CAPACITY FOR IMPROVING RUST RESISTANCE.