Seasonal variation in yield, nutritive value, and antioxidant capacity of leaves of alfalfa plants grown in arid climate of Saudi Arabia

Abstract

In addition to its high nutritional value, alfalfa (Medicago sativa L.) has several health benefits including antioxidant, neuroprotective, antimicrobial, antiulcer, hypocholesterolemic, hypolipidemic, and estrogenic effects. We aimed to assess the nutritional value and antioxidant capacity of alfalfa leaves at different times of the year in arid regions. Alfalfa was harvested in autumn, winter, spring, and summer and fresh yield and leaf:stem ratio were measured. Leaves were collected to determine their nutritional value and antioxidant capacity using two different extracts viz.: absolute ethanol or distilled water. Fresh yield and leaf:stem ratio were highest in spring (20 t ha -1 and 57.6%, respectively), followed equally by winter and autumn, and were lowest in summer (10.75 t ha -1 and 51.6%, respectively). The autumn cut had the highest crude protein (33.52%) and crude fat content (3.79%) and the lowest content of crude fiber (13.95%) and acid detergent fiber (16.55%), which are good indicators of suitability for human nourishment. However, leaves collected in autumn were characterized by lower digestibility values (86.2%) compared to the other cuts. Antioxidant capacity of leaves harvested in autumns and extracted with either ethanol or distilled water was examined in terms of total polyphenols, total flavonoids, DPPH scavenging capacity, and reducing power. Ethanol extract showed higher antioxidant capacity in terms of total phenol and total flavonoid contents (6.41 and 4.88 mg gallic acid equivalents g -1 DW, respectively). These results suggest that autumn is the most appropriate season to cut alfalfa leaves for human nutritional purposes.

Enhancing growth, quality, and metabolism of nitrogen of alfalfa (Medicago sativa L.) by high red–blue light intensity

“…Within a certain range, it has been documented that the soluble sugar content in plant leaves increases proportionally with higher light intensities, as observed in various vegetables and crops such as spinach and soybeans (Almeida et al, 2021;Zou et al, 2020;). In this study, the soluble sugar content of alfalfa during a 30-day harvest period the shoot and root of alfalfa possess the ability to scavenge DPPH free radicals (Gao et al, 2020;Soufan et al, 2021). In this study, the DPPH free radical scavenging rate of ethanol extracts obtained from alfalfa during a 30-day harvest period exhibited a gradual increase under light treatments ranging from 400 to 600 µmol m −2 s −1 .…”

“…The evaluation of the antioxidant activity of plants often involves the utilization of the DPPH free radical scavenging rate. Previous studies have demonstrated that the ethanol extracts derived from both the shoot and root of alfalfa possess the ability to scavenge DPPH free radicals (Gao et al., 2020; Soufan et al., 2021). In this study, the DPPH free radical scavenging rate of ethanol extracts obtained from alfalfa during a 30‐day harvest period exhibited a gradual increase under light treatments ranging from 400 to 600 µmol m −2 s −1 .…”

Influence of Plant Origins and Seasonal Variations on Nutritive Values, Phenolics and Antioxidant Activities of Adenia viridiflora Craib., an Endangered Species from Thailand

“…Our results concurred with previous reports on other plants. The autumn (high total rainfall) harvest of Medicago sativa L. from Saudi Arabia provided high human nutrition (high crude protein and fat but low crude fiber) [25], while protein contents in Acacia brevispica, Acacia nilotica, Acacia seyal, Acacia tortilis, Balanites aegyptiaca, Grewia bicolor, Grewia tembensis, and Rhus natalensis from Southern Ethiopia harvested during the rainy season were higher than recorded in the hot dry season [26]. Similar results were observed in Cladium mariscus L. Pohl (sawgrass) from Southern Portugal, where crude protein and fat contents were higher in spring than during other seasons, while fiber was lowest [27].…”

Antioxidant Activity, Phenolic Content, and Antioxidant Gene Expression in Genetic Resources of Sorghum Collected from Australia, Former Soviet Union, USA, Sudan and Guadeloupe

“…Studies on the relationship between the biological activity of sorghum and the precipitation and climate of the growing region were conducted; however, it is difficult to determine their correlation because sorghum grows well even in a barren climate [9]. A study on the antioxidant activity and nutritional value of alfalfa leaves found that they were greatly influenced by climate according to seasonal changes [10]. The ascorbic acid content in potatoes varies considerably among cultivars exposed to different environments in Europe [11].…”