Effects of seeding rate on growth and productivity of barley grown under conservation agriculture conditions in the Saïss

Abstract

This study aims to evaluate the effect of different seeding rates on growth, productivity, and economic profitability of barley (Hordeum vulgare L.) grown in rainfed conditions under conservation agriculture in the Saïss region (Meknes, Morocco) during the 2024-2025 growing season. Four seeding rates were tested: 70 (T1), 100 (T2), 130 (T3), and 160 (T4) kg/ha, distributed in randomized complete blocks with four replications. The results showed that the seeding rate had a significant effect on most of the studied parameters. At emergence, plant density increased proportionally with the seeding rate, ranging from 146 plants/m² for T1 to 336 plants/m² for T4. However, low densities (T1) promote greater tillering per plant, with T1 recording an average of 7 tillers/plant at stem elongation compared to 5 tillers/plant for T4. In terms of vertical growth, high densities (T4) showed greater plant height (115.4 cm at heading), reflecting increased competition for light and reduced etiolation. However, total dry matter per plant decreases significantly with increasing density, with T1 reaching an average of 9.41 g/plant at maturity while T4 only reaches 3.65 g/plant. The density of ears per m² increases significantly with the seeding rate, averaging 462 ears/m² for T4 and 354 for T1, but this is accompanied by a very significant decrease in the number of grains per ear and a downward trend in thousand-grain weight. Regarding final yields, despite variations in the average, the effect of seeding rate on grain, straw, and biological yield was not significant. Treatment T1 obtained, on average, the highest grain yield (46.4 qx/ha), as well as the highest straw (74.6 qx/ha) and biological (136.3 qx/ha) yields. Lodging, the incidence of which increased significantly with plant density (R² = 63.2%) and plant height (R² = 61.6%), significantly reduced individual grain components, notably thousand-grain weight (R² = 47.6%) and the number of grains per ear (R² = 62.9%). Total production costs increased with seeding rate, rising from 3139 MAD/ha for T1 to 3481 MAD/ha for T4. Despite the lack of statistical significance for total income, T1 generated the highest total income (19,315 MAD/ha), while T4 had the lowest (17,306 MAD/ha). Net margin, for which the analysis of variance tends toward significance, was also highest for T1 (16,176 MAD/ha) and lowest for T4 (13,825 MAD/ha).

 Keywords: seeding rate, conservation agriculture, barley, growth parameters, productivity, economic profitability, Saïss, Morocco