EVALUATION OF FINGER MILLET GENOTYPES AS CLIMATE SMART CROP UNDER THE AGROCLIMATE OF JORHAT
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Date
2023
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Abstract
A field experiment was conducted during kharif, 2022-23 at Instructional cum
Research (ICR) Farm of Assam Agricultural University, Jorhat to study crop weather
relationship and genetic diversity among five finger millet genotypes viz. Gossaigaon
Maruadhan (V1), FMAVT 4001 (V2), FMAVT 4006 (V3), FMAVT 4007 (V4) and
FMAVT 4012 (V5) grown under three microclimatic regimes: 6th August (D1), 22nd
August (D2) and 6th September (D3), following split plot design with three replications.
The weekly mean maximum (Tmax) and minimum temperature (Tmin), rainfall (RF),
morning (RH-I) and evening relative humidity (RH-II), bright sunshine hours (BSSH), pan
evaporation (EVP) and wind speed (WS) ranged from 22.1ºC to 34.9ºC, 7.9ºC to 25.6ºC, 0
to 104.4 mm, 91 to 100%, 51 to 85%, 1.9 to 9 hours, 1.1 to 3.8 mm and 0.8 to 3.1 kmph
respectively during the period of experimentation. Biometric observations, viz. plant height,
leaf area index (LAI), biomass, number of effective tillers/m2, number of earheads/m2,
number of fingers per earhead, finger length, test weight, grain and straw yield were
recorded periodically during entire growing season and at the time of harvest. Soil
temperature at 10 cm depth was recorded daily, soil moisture at 15 days interval and
incident, reflected and transmitted photosynthetically active radiation (PAR) at 7 days
interval were also recorded during the experimental period. Results revealed that LAI,
plant height and biomass at all the growth stages differed significantly under different
microclimatic regimes with highest values recorded in the early sown (D1) crop.
Accumulated agroclimatic indices such as GDD (growing degree days), HTU
(heliothermal units) and PTU (photothermal units) decreased gradually with successive
delay in sowing time with highest value being recorded under D1. Yield attributes and
grain yield were found highest in early sown crop (D1) as compared to late sown crops.
The vegetative phase of the first sown (D1) crop was exposed to comparatively higher soil
temperature regime as compared to late sown crops (D2 and D3). The crop sown on 6th
August (D3) had the highest PAR interception rate (72.6%). Among the genotypes,
Gossaigaon Maruadhan (V1) was found to be superior with respect to growth parameters
and yield (17.94 q/ha). Correlation analysis revealed that yield attributes and yield were
significantly positively correlated with Tmax, Tmin, and WS whereas the correlation was
negative and significant with RHI during all growth phases. EVP and BSSH had
significant positive association with yield and yield attributes in all the phases of the crop
growth except during reproductive phase. Yield predictive models were developed by
utilizing step-wise multiple regression method using mean and accumulated agroclimatic
indices during different pheno phases and entire period of crop growth. The most efficient
yield predictive model among mean phasic meteorological parameters was found with
Tmin during vegetative phase with highest coefficient of determination (R2=0.932)
irrespective of varieties. While, among the accumulated meteorological indices, the best
models were found for PTU (R2=0.932) and RF (R2=0.932) during vegetative phase and
entire growing period respectively. For genetic diversity analysis, 20 RAPD primers were
used out of which 7 were found to be polymorphic. These markers amplified 46 alleles
with an average of 4.6 alleles per marker. Genetic relationship among finger millet
genotypes were found out on the basis of pairwise Jaccard’s similarity coefficient whose
value ranged from 0 to 0.6 with an average of 0.295. Cluster analysis by UPGMA method
grouped 20 samples into two major clusters, each further sub-divided into two sub-clusters.
Cluster A comprised of 15 samples while cluster B had only 5 samples. All the treatment
combinations of varieties V2, V3, V4 and V5 were grouped in cluster A, while treatment
combinations of V1 were grouped in cluster B which indicates their genetic dissimilarity.
These results indicated that different plant characters exhibiting strong positive genotypic
and phenotypic correlation with grain yield can be used for development of high yielding
genotypes of finger millet crop.