Characteristics of Carbon, Nitrogen and Phosphorus Stoichiometry and Nutrient Reabsorption in Alfalfa Leaves with Different Fall-Dormancy Levels in Northern Xinjiang, China

Abstract

Alfalfa productivity and cold resistance in different regions are influenced by the fall-dormancy level of alfalfa. However, it is unclear whether the stoichiometric characteristics and nutrient resorption efficiency in alfalfa leaves also vary with the fall-dormancy level. In order to further understand the differences in nutrient absorption and requirements of different fall-dormant alfalfa, we conducted field trials on 30 different fall-dormancy alfalfa cultivars for 2 consecutive years in 2020 and 2021. We investigated the concentrations of carbon, nitrogen, and phosphorus in mature and senescent alfalfa leaves; nutrient stoichiometry ratios; and the coupling relationship between nutrient reabsorption efficiency and dry matter yield. The differences in nutrient reabsorption, fall dormancy, and dry matter yield of different fall-dormant alfalfa, and the correlation between indicators were utilized to further analyze the regulatory mechanisms of nutrient reabsorption in different fall-dormancy alfalfa varieties. The results demonstrated that the nitrogen reabsorption efficiency (NRE) and phosphorus reabsorption efficiency (PRE) of leaves increased first and then decreased with the increase in fall dormancy, whereas the carbon reabsorption efficiency (CRE) showed the reverse tendency. Different fall-dormancy alfalfa varieties significantly affected the dry matter yield and nutrient absorption in the first cut, while the last cut had the lowest variable coefficient and impact. There was a significant decrease in the over-winter survival rate of alfalfa as the fall-dormancy level increased, whereas the over-summer survival rate was less affected by the fall-dormancy level. As the growth year increased, there was a significant decrease in the over-winter survival rate. Among mature leaves, the NRE and PRE showed a significant positive correlation with the C concentration, while they showed a significant negative association with the N and P concentrations. In the same cut, the dry matter yield decreased with the increase in CRE but increased with the increases in NRE and PRE, while there was no significant trend in dry matter yield and nutrient resorption efficiency (NuRE) between different cuts. Taken together, the alfalfa survival rate and dry matter yield were relatively better in the moderate fall-dormancy (fall-dormancy level, FD = 4, 5) types and fall-dormancy (FD = 3) type, with a corresponding increase in the reabsorption requirements for nitrogen and phosphorus.

The Responses of C, N, P and Stoichiometric Ratios to Biochar and Vermicompost Additions Differ from Alfalfa and a Mine Soil

“…Carbon (C), nitrogen (N), and phosphorus (P) play vital roles in plant growing processes and physiological regulations [1,2]. C is a necessary energy element in plants.…”

Stoichiometric characteristics drive the soil aggregate stability after 5 years of vegetation restoration in China

“…Soil carbon (C), nitrogen (N) and phosphorus (P) stoichiometry has been extensively studied around the world in recent decades (Cleveland and Liptzin, 2007;Bai et al, 2012;Sun et al, 2022;Wang et al, 2022). Soil aggregate stability and its stoichiometric characteristics are the effective ways to evaluate the effect of soil restoration and various sized aggregates play different roles in the supply and transport of soil C, N, and P (Chen et al, 2021;Tang and Wang, 2022).…”

A Thermal Time Basis for Comparing the Germination Requirements of Alfalfa Cultivars with Different Fall Dormancy Ratings

“…The vast genetic and phenotypic variations in alfalfa permit its cultivation in large geographic regions with diverse climate and environmental conditions [6][7][8][9]. Alfalfa cultivars that developed from different geographic regions have distinct characteristics in fall dormancy [9].…”

“…Fall dormancy in alfalfa is also related to other important traits including initiation of spring growth, growth habit, root growth traits, stand persistence, and herbage yield and quality [4,7,[14][15][16]. In major alfalfa-producing countries such as the United States and Canada, fall dormancy is treated as the primary indicator for assessing cultivar characteristics [17].…”