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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. [ABSTRACT FROM AUTHOR]

Rational water and fertiliser management have an important impact on alfalfa production. This research aimed to explore the effects of water and phosphorus (P) fertiliser on water‐use efficiency (WUE) and phosphorus‐recovery efficiency (PRE) of each cut of alfalfa under drip irrigation and to determine the optimal interaction ratio of water and phosphorus to improve the quality and yield of alfalfa. Different irrigation levels were set, i.e., 5250, 6000 and 6750 m3/ha (referred to as W1, W2, W3, respectively), and P fertiliser levels (0, 50, 100 and 150 kg/ha P2O5 referred to as P0, P1, P2, P3, respectively) were set to determine the hay yield and nutrient quality of each cut of alfalfa under drip irrigation. The hay yield of each cut of alfalfa increased first and then decreased with increased P fertiliser under the same irrigation amount. WUE decreased gradually with an increasing amount of irrigation under the same P application rate. The WUE of alfalfa increased first and then decreased with the increase of P application rate under the same irrigation amount, and WUE was 0.20%–4.75% (2016) and 1.31%–6.22% (2017) higher in the P treatments than in the non‐phosphorus treatments. PRE decreased gradually with increasing P application rate under the same irrigation amount. Therefore, we concluded that moderate irrigation (6000 m3/ha) and P fertiliser (100 kg/ha) optimised WUE, PRE, hay yield and nutrient quality. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the nitrogen (N) and phosphorus (P) fertilization of continuous addition effects plant biomass, the physiological properties of leaves and the antioxi-dant enzyme activities of alfalfa (Medicago sativa L) in the northern Xinjiang region; including the no fertilization (CK), nitrogen fertilization (N, 120 kg·ha−1), phosphorus fertilization (with low amount of N) (P, 100 kg·ha−1 P and 23.5 kg·ha−1 N) and combined nitrogen and phosphorus fertilization (NP, 120 kg·ha−1 N and 100 kg·ha−1 P) on the K well supplied soil. After three consecutive years of the supply of N and P fertilization, samples were taken at the first flowering of alfalfa (four clippings in the total year) to determine its pigment concentration, stomatal aperture, antioxidant enzyme activity and hay yield. The results showed that NP fertilization promoted growth with a higher number of branches and hay yield of alfalfa, while N or P fertilization alone had a positive effect on the growth of alfalfa. However, P fertilization significantly increased the carotenoid (Car) content at the early flowering stage of alfalfa leaves (during four clippings) (p < 0.05), In addition, NP ferti-lization enhanced stomatal aperture, increased the antioxidant enzyme activity and decreased the oxidized substance at the early flowering stage of alfalfa leaves. The results showed that a N and P balance rather than an absolute amount of either enhanced the growth of alfalfa, and N or P fertili-zation affects physiological traits differently. We propose that NP fertilization increases the nutri-tional characteristics and physiological characteristics, enhancing the adaptive capacity of alfalfa and making it better adapted to external environmental changes. [ABSTRACT FROM AUTHOR]

The productivity of alfalfa is associated with a large amount of nitrogen (N) and phosphorus (P); the addition of exogenous N and P fertilizers can fully exploit the growth potential of alfalfa. However, there is uncertainty about the relationship between changes in alfalfa productivity and photosynthetic physiology and anatomy. We conducted field fertilization experiments on alfalfa in the second and third years under drip irrigation, as well as measurement of the photosynthetic physiology, anatomical structure and agronomic traits of alfalfa at different levels of N (0, 120 kg·ha−1) and different levels of P2O5 (0, 50, 100 and 150 kg·ha−1). The results showed that the dry matter yield (DMY), crude protein (CP), net photosynthetic rate (Pn) and specific leaf weight (SLW) were increased by 2.10~11.82%, 4.95~11.93%, 4.71~7.59% and 2.02~7.12% in the N application treatment compared with the non-N application treatment, while the DMY, CP, Pn and SLW were increased by 3.19~17.46%, 1.99~8.42%, 6.15~24.95% and 2.16~11.90% in the P application treatment compared with the non-P application treatment. N and P increase the thickness of the spongy tissue (ST) of alfalfa, which will facilitate the entry and exit of gas and water, and will further affect the photosynthetic indexes, such as stomatal conductance (Gs) and transpiration rate (Tr), of alfalfa leaves. Increased palisade tissue (PT) thickness will also enhance the adaptability of plant leaves to strong sunlight, thereby increasing the maximum net photosynthetic rate (Pmax) and light saturation point (LSP). Fertilization treatment showed the highest utilization efficiency for low light and better adaptation to strong light, but the Rd decreased. The comprehensive scores of principal component analysis for anatomical structure, photosynthetic performance and agronomic traits were N1P2 > N0P2 > N1P3 > N1P1 > N0P3 > N0P1 > N1P0 > N0P0. Therefore, the application of N and P fertilizers contributed to the adaptive changes in alfalfa leaf anatomy and the improvement of photosynthetic capacity, which were beneficial to the improvement of alfalfa dry matter yield, growth traits and nutritional quality, with the most obvious improvement effect obtained with the application of 120 kg·ha−1 of N and 100 kg·ha−1 of P2O5. [ABSTRACT FROM AUTHOR]

• Agroforestry systems (AF) with narrow rows were compared with sole crops. • AF caused an overall decrease in yield and protein content of understory crops. • Yield and protein content of understory crops and PAR were highest in the center. • The AF systems may provide greater long-term economic benefits. The objective of this study was to determine the effects of agroforestry systems with narrow rows on microclimate, crop quality, productivity, and revenue when compared with that in sole-cropping in drylands. Therefore, two-year field experiments were conducted to determine the characteristics of two types of agroforestry systems in drylands of Xinjiang including photosynthetically active radiation (PAR), air temperature, crop protein content, productivity, and revenue. The two systems included (1) a jujube tree (Zizyphus jujuba Mill.) + wheat (Triticum aestivum L.) intercropping (JWI) system and (2) a poplar tree (Populus L.) + alfalfa (Medicago sativa L.) silvopastoral (PAS) system located in southern and northern Xinjiang, respectively. Variables were measured in control sole-cropping plots and in the alleys of JWI and PAS system plots at different distances from the tree row. PAR and air temperature both decreased in plots of the JWI and PAS systems. The changes in microclimatic conditions and competition for resources in the JWI and PAS systems resulted in an overall decrease in wheat grain and alfalfa hay yield and decreases in the overall protein content of wheat grain and alfalfa. In JWI and PAS systems, the yield and protein content of understory crops, PAR, and air temperature were highest at the center line of the system alley and decreased with decreasing distances from the tree row. The PAS system was more productive than the JWI system based on the calculated land equivalent ratio (LER), because no significant decrease was observed in tree yield in the PAS system. Both the JWI and PAS systems resulted in an increase in the annual total crop revenue when compared with individual crop management, indicating that the JWI and PAS systems could provide greater long-term economic benefits. Therefore, the balance between yield, crop quality, and revenue have to be taken into account in the analysis of agroforestry systems. [ABSTRACT FROM AUTHOR]