Genotypic variability and interrelationships among earliness and yield-related traits in bread wheat cultivars under different phosphorus levels and nitrogen forms

الملخص EN

This study aimed toassess the genotypic variability among high-yielding bread wheat cultivars evaluated under three phosphorus (P) levels and three nitrogen (N) forms, clarifying the relationship between earliness and yield traits, and determining the amount of direct and indirect impacts of attributed agronomic traits on grain yield.

The field experiment was carried out at Om-Elzain village, Zagazig, during 2017-18 and 2018-19 growing seasons.

The results revealed that the evaluated cultivars revealed significant variation for all studied traits.

Similarly, P levels presented significant effects on earliness and most yield traits in both seasons.

While the N forms did not significantly affect all studied traits in both seasons except plant height, number of spikes/m², and 1000-grain weight.

The phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV) for all evaluated traits.

The difference between PCV and GCV was very low for days to heading, days to maturity and number of spikes/m², while it was relatively higher for number of grains/spike and biological yield.

The heritability in broad sense (h²_b) values were high for 1000-grain weight, number of spikes/m², and days to maturity.

Plant height, spike length, number of spikes/m², number spikelet/spike, 1000-grain weight and biological yield displayed positive direct effect on grain yield.

The highest indirect effects on grain yield were assigned for plant height, 1000-grain weight and flag leaf area through biological yield