EFFECT OF POTASSIUM FERTILIZER ON SPRING SUNFLOWER GENOTYPES IN IRAQ

Abstract

With the aim of studying different levels of potassium fertilizer and its effect on the performance of different varieties of sunflower crops, estimating heritability at all levels of fertilizer, and determining which variety gives a higher yield, a field experiment was carried out in a private field outside the university for the spring season of 2025. The land was prepared for cultivation at the experiment site by plowing, smoothing and leveling according to recommendations. An RCBD design was used with three replicates, according to the split-plot arrangement, fertilization levels (0.0-, 0.1-, 0.2-, and 0.3-ton K ha-1) were distributed on the main plots, and the varieties (Aqmar, Local, Ishaqi1, Ishaqi2, and Tarazan) were distributed on the secondary plots. The results showed that the fertilizer level exceeded 0.1 ton K ha-1 with the highest yield per individual plant reaching 109.14 g due to its superiority in the highest plant height (221.87 cm) with the highest number of leaves (31.20 leaf plant-1), the highest leaf area index (5.537), the highest disc weight (188.22 g), the lowest number of days to reach physiological maturity (94.00 day), the highest crop growth rate (4.447 g plant day-1). The Tarazan variety excelled with the highest individual plant yield of 95.08 g due to it having a high number of green leaves (29.00 leaf plant-1) and a high leaf area index (4.930). It also had the highest disc weight (127.65 g) and the highest crop growth rate (4.172 g plant day-1). The standard error values and coefficient of variation were low for the traits studied and at the four fertilization levels, the genetic variation was greater than the environmental variation for most of the traits studied, the percentage of heritability in the broad sense was very high for all the traits studied at the potassium fertilization level of 0.0 ton K ha-1, ranging between 91.9% and 99.0% for the two traits of individual plant yield and the number of days to physiological maturity. Heritability was high for all traits at the level of 0.1 ton Kha-1, ranging between 68.7% and 98.9% for the two traits of the number of days of physiological maturity and leaf area index, while the heritability in the broad sense was high for most traits at the fertilization level of 0.2 ton Kha-1, ranging between 86.4% and 99.5% for the weight of 500 seeds and number of days to physiological maturity, and the heritability was high for most traits at the high level of fertilizer (0.3 ton K ha-1), ranging between 73.9% and 99.8% for the two traits, number of days to physiological maturity and crop growth rate, the heritability was medium for the trait of plant height reached 55.2%.