Genetic Variability, Genetic Parameters, Growth Characteristics and Yield of Three Garlic (Allium sativum L.) Varieties under Amino Acids and Salicylic Acid Treatments

Abstract

This study, conducted in Nineveh Governorate, Iraq, investigated the inheritance of certain growth and yield traits. It was carried out during the autumn growing season of 2025-2026 at the Agricultural Research Field, College of Agriculture and Forestry, Mosul. The aim was to estimate the genetic parameters of three garlic cultivars (Iranian, Chinese, and French) under the influence of foliar application of the amino acid casein hydrolysate at three concentrations (0, 1, and 2 g/L) and salicylic acid at two concentrations (0 and 2 g/L). The experiment consisted of eighteen treatments in a completely randomized block design with three replications.The results of the analysis of variance indicate significant differences between the mean squares of the three classes for all the traits under study, except for the traits of total leaf chlorophyll content and the percentage of nitrogen and potassium in the leaves, where the differences did not reach the threshold of significance. The values of genetic variance were significant above zero for all the studied traits except for the traits of total leaf chlorophyll content and the percentage of total soluble solids in the lobes, while the values of environmental variance were significant above zero for all the traits. Heritability in the broad sense was high for the traits of plant height 0.962, number of leaves 0.657, leaf area of the plant 0.905, average bulb weight 0.720, bulb length 0.824, bulb diameter 0.776, average lobe weight 0.651, lobe length 0.863, lobe diameter 0.670, total plant yield (bulbs + leaves) 0.717, total bulb yield 0.720, and marketable bulb yield 0.720. The high heritability is evidence that the appearance of the individual is greatly related to its genetic makeup, and this indicates the possibility of introducing direct improvements to these traits in subsequent seasons. The expected genetic improvement values as a percentage of the average trait were between low for the traits of number of leaves 9.525, total leaf chlorophyll content 3.231, percentage of dry matter in the vegetative body 2.786, number of lobes per bulb 5.188, bulb percentage 6.529, percentage of total soluble solids in the lobes 3.207, percentage of nitrogen in the leaves 1.923, and percentage of potassium in the leaves 3.917. The average for plant height is 22.333, bulb length is 29.206, bulb diameter is 23.732, lobe length is 29.734, lobe diameter is 20.576, and the percentage of phosphorus in the leaves is 10.919. The high for plant leaf area is 43.732, average bulb weight is 51.171, average lobe weight is 42.258, total plant yield (bulbs + leaves) is 34.644, total bulb yield is 51.174, and marketing yield of bulbs is 51.174.