Relationship between stomatal conductance and drought susceptibility index in alfalfa (Medicago sativa L.)

Global climate change evidentiate an increase in drought frequencies. In this context the strategies for sustainable use of water and drought resistance improvement based on the physiological traits are important and physiological approaches should be integrated in conventional breeding. Research was performed on 16 alfalfa genotypes under vegetation house conditions at two watering levels and field analyses. The objective was to identify the available genetic variation and to establish efficient physiologycall traits for testing which might positively influence alfalfa performance under drought conditions. Our research were focused on stomatal conductance and chlorophyll content. There is a very significant negative correlation between the drought sensitivity index and the stomatal conductance of alfalfa genotypes sown for fodder (r = - 0.70***). This means that genotypes with a higher stomatal conductance were more productive (low drought sensitivity index means better drought adaptability, so higher production) indicating that stomatal resistance has a very significant impact on production under stress conditions. There is a very significant positive correlation between the chlorophyll content and the stomatal conductance of alfalfa genotypes from the comparative culture sown for fodder (r = 0.79***), which shows that stomatal closure is the main factor limiting photosynthetic activity under water limiting conditions

FORAGE MIXTURES WITH ALFALFA CULTIVARS, PERENNIAL GRASSES AND ANETHUM GRAVEOLENS

Fodder crops consisting of several species are a way to obtain very good quality feed. They have been used more and more recently in Europe because, in addition to the superiority of feed production and quality, sowing mixtures of several species can lead to a significant reduction in the need for nitrogen fertilizer, an increase in performance and animal health. In Romania, there are few studies on the use of multi-species feed mixtures to reduce dependence on expensive inputs in order to increase the profitability and quality of feed, in organic agriculture production system. The objective was to compare forage yield, degree of coverage and weed infestation of alfalfa single crop and perennial grasses mixtures, which include 10 synthetic alfalfa cultivars and 5 varieties, grasses (a cultivar of Dactylis glomerata, Festuca arundinacea, Phleum pratense), mixed with herb Anethum graveolens. A field experiment was established in 2022 in the experimental field of the Center for Organic Agriculture at NARDI Fundulea. The results showed that mixtures of alfalfa with dill and festuca had a higher yield than alfalfa in pure crop. Anethum graveolens seeded with forage mixtures proved the efficacy as a natural repellent of Hypera variabilis in the first year of crop. In general, alfalfa-grass mixtures had beside higher feed yields and lower weed and pests infestations than alfalfa monocultures or mixtures of two species

Development and Validation of an RP-HPLC Method for Methionine, Cystine and Lysine Separation and Determination in Corn Samples

In this paper a RP-HPLC method is developed and validated. Using a Hypersil BDS C18 column, a mobile phase: solvent A (phosphate buffer) and solvent B (water : acetonitrile : methanol, 20:20:60 v/v/v), a 45°C column temperature and a flow rate of 1.7 mL/min, the proposed method proved a good separation of the investigated amino acids, in 35 minutes