Effect of Planting Dates and Potassium Application on Wheat Tolerance to Irrigation with Saline Water

Abstract

The experiment investigated the effects of planting dates, irrigation water quality, and potassium 
fertilizer levels on wheat growth, yield, and selected soil chemical and physical properties under saline 
irrigation conditions. The study was conducted during the 2024–2025 agricultural season in Al-Akhd 
area, Al-Rifai District, Dhi Qar Governorate. The field was prepared using standard plowing and 
leveling practices, and the experiment was arranged in a Randomized Complete Block Design (RCBD) 
with a split–split plot arrangement and four replications. Planting dates were assigned to main plots, 
irrigation water quality (fresh and saline) to subplots, and potassium fertilizer levels (0, 60, and 120 kg 
ha⁻¹ as potassium sulfate) to sub-subplots. Wheat cultivar Nazar was planted on two dates, while 
recommended nitrogen and phosphorus rates were applied uniformly. Potassium was added according 
to treatment levels. Results showed that the early planting date (November 1) numerically exceeded 
the late date in most traits, including number of spikes and grains per spike, although differences were 
not statistically significant. Planting dates had no significant effect on plant height, 1000-grain weight, 
or harvest index. Potassium fertilization had a significant positive effect on number of spikes, grain 
yield, 1000-grain weight, and harvest index, with increases observed as potassium levels increased 
from K0 to K2. However, the number of grains per spike decreased significantly with higher potassium 
levels. Fresh irrigation water showed numerical superiority over saline water in most traits, though 
differences were generally non-significant. The highest grain yield was obtained under early planting 
with fresh water, while the lowest occurred under late planting with saline water. Overall, potassium 
fertilization was the most influential factor in improving wheat performance under saline irrigation 
conditions.