Spike, Flag-leaf and Canopy Diversity of Genotypes across Twelve Different Environments in Bread Wheat (Triticum aestivum L.)
Amit Nagar *
Department of Genetics and Plant Breeding (Ag. Botany), JV College, Baraut, Baghpat 250611 (U.P), India.
R. K. Gupta
Department of Genetics and Plant Breeding (Ag. Botany), JV College, Baraut, Baghpat 250611 (U.P), India.
Ashvani Panwar
Department of Genetics and Plant Breeding (Ag. Botany), Gochar Mahavidyalaya, Rampur Maniharan, Saharanpur (U.P), India.
Satish Kumar
Department of Genetics and Plant Breeding, Chaudhary Charan Singh University Meerut, Uttar Pradesh, India.
*Author to whom correspondence should be addressed.
Abstract
This study evaluated spike, flag-leaf and canopy diversity among 60 bread wheat genotypes across 12 environments generated from two locations, two growing seasons and three sowing times. Five traits-spike length (SL), flag leaf area (FLA), spikelets per spike (SNPS), grains per spike (GPS) and canopy temperature (CT)-were assessed using environment-wise genotype means. Genotypic and phenotypic coefficients of variation and broad-sense heritability were compared, and a separate five-trait Mahalanobis distance and average-linkage hierarchical clustering analysis was conducted for each environment. Mean FLA across environments ranged from 18.05 to 39.49 cm², whereas mean GPS ranged from 34.53 to 57.37. Mean CT ranged from 23.70 °C in E1 to 33.93 °C in E6. Reported PCV values ranged from 17.09 to 29.62% for FLA and from 1.99 to 10.25% for SNPS. Broad-sense heritability ranged from 16.99 to 67.70% for SL and from 4.97 to 96.55% for GPS. Five-cluster solutions also differed among environments, with cluster sizes ranging from 1 to 55 genotypes. The results show that phenotypic diversity for spike, flag-leaf and canopy traits was sensitive to site, season and sowing conditions. Consequently, potentially useful breeding material should be evaluated across environments and selected on the basis of specific trait performance and consistency rather than multivariate distance or single-environment extremes alone.
Keywords: Bread wheat, canopy temperature, flag leaf area, broad-sense heritability, genetic divergence, genotype-environment variation, Mahalanobis distance, phenotypic variability, sowing environment, spike architecture