Overwintering and yield responses of two late-summer seeded alfalfa cultivars to phosphate supply

Authors: WANG, YUNTAO - Chinese Academy Of Agricultural Sciences; YU, LINQING - Chinese Academy Of Agricultural Sciences; ZHANG, JIAGENG - Chinese Academy Of Agricultural Sciences; Xu, Zhanyou; Samac, Deborah - Debby

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2022
Publication Date: 1/26/2022
Citation: Wang, Y., Yu, L., Zhang, J., Xu, Z., Samac, D.A. 2022. Overwintering and yield responses of two late-summer seeded alfalfa cultivars to phosphate supply. Agronomy. 12(2). Article 327. https://doi.org/10.3390/agronomy12020327.
DOI: https://doi.org/10.3390/agronomy12020327

Interpretive Summary: Phosphorus (P) is a key nutrient for plant growth and development. Alfalfa plants have high requirements for P because much of the accumulated P is removed with the herbage at each harvest. However, few studies have determined the optimal P fertilization rates, particularly in stressful environments. This study used a dormant and semi-dormant alfalfa cultivars planted and fertilized in the autumn and measured yield components; plant density, stem number, yield at each harvest; crown and root traits; and winter survival with different rates of P fertilizer. For most traits a P fertilizer rate of 100 kg per hectare applied as calcium phosphate improved plant performance, especially for the semi-dormant cultivar. This information can be used for establishing alfalfa in dry arid regions where fall seeding is recommended to increase plant survival, herbage yields, and reduce costs from over-application of P fertilizer.

Technical Abstract: Alfalfa (Medicago sativa L.) is an important forage legume in the crop, pasture, and animal husbandry systems in northern climates. However, low forage production and poor winter survival often occur, leading to significant economic losses. The objective of this study was to determine the effect of different phosphate (P) fertilization rates (0, 50, 100, and 150 kg ha-1) on winter survival, forage yield, and crown and root traits of alfalfa seeded in autumn of the year. Our results showed that applying the appropriate amount of P fertilizer can increase forage yield and promote crown and root traits that increase winter survival, especially in semi-dormant alfalfa cultivars. Taproot diameter, depth of the first lateral root, and the number of lateral roots of the semi-dormant alfalfa were more sensitive to P fertilizer than the dormant cultivar. Autumn seeding and application of appropriate P fertilizer rates was an effective new cultivation method for alfalfa in the cold and arid winter region in which the study was done. A P fertilizer rate of 94.8 kg ha-1 was calculated to be the optimal fertilizer rate for winter survival, and a rate of 71.4 kg ha-1 was optimal for alfalfa production in the temperate continental climate zone with gray-cinnamon soil.