Abstract: Appropriate seeding rate and row spacing are essential for optimizing alfalfa hay yield and quality. This paper reports a field experiment conducted from 2015 to 2017 to study the effects of seeding rate and row spacing on alfalfa hay yield, quality and other traits at the Dongying Academy of Agricultural Sciences experimental base, in the Huang-Huai-Hai area of Shandong Province. The Medicago sativa cultivar used was Zhongmu No.3. The experiment used a randomized complete block design with three replicates. Each replicate had 9 treatment combinations. Treatments were arranged as 3×3 factorial combination of three seeding rates (7.5, 15.0 and 22.5 kg·ha^-1) and three row spacings (15, 30 and 40 cm). Individual plot size was 5 m by 6 m, with 1.0 m spacing between the adjacent plots. This study was designed to determine the optimum seeding rate and row spacing when cropping alfalfa on saline-alkali land. It was found that seeding rate had significant effects on the yields in the establishment year but no significant effects on total yields over three years. Yield increased with seeding rate and the highest total yield was obtained at the seeding rate of 22.5 kg·ha^-1. There were significant differences for three years yields among row spacing treatments, with the total yield of the 15 cm row spacing treatment being the highest, and wider row spacings giving lower yields. The row spacing effect was large during establishment year, and gradually diminished over successive growing seasons. Considering seeding rate and row spacing, the combination of 22.5 kg·ha^-1 seeding rate and 15 cm row spacing resulted in the highest total yield over three years. Seeding rate and row spacing significantly affected the number of branches per m^-2 and branch weight. With increase in seeding rate and decrease of between-row spacing, the number of branches per m^-2 increased while the weight of branches decreased. There was a significant positive correlation between crop yield and number of branches per m^-2, and a significant negative correlation between crop yield and branch weight. With increase in seeding rate and decrease in row spacing, crude protein and relative feed value increased, but neutral detergent fiber and acidic detergent fiber levels decreased. The highest feed quality value was obtained with 22.5 kg·ha^-1 seeding rate and 15 cm row spacing. Based on both yield and feed quality data, the optimal planting regime at this site was 22.5 kg·ha^-1 seeding rate and 15 cm row spacing. In conclusion, it is recommended to plant saline-tolerant alfalfa varieties at a seeding rate of 22.5 kg·ha^-1 and a row spacing of 15 cm in saline-alkali land of Shandong province and Huang-Huai-Hai areas. The effects of seeding rate and row spacing on yield diminished in successive growing seasons. Optimal seeding rate and row spacing is helpful to improve the yield and quality of alfalfa crops.

Key words: alfalfa, seeding rate, row spacing, yield, quality