| Abstrakt: |
The paper presents the assessment of light interception and absorption patterns, canopy structure and aerial dry matter allocation in 27 alfalfa varieties grown in the eco-climatic conditions of Gherghita Plain, Romania, and whether the results can lead to the improvement of cropping technologies for obtaining superior forage yields and better winter hardiness. Alfalfa is a perennial crop that produces its highest yields during the second year of growth and the paper emphasizes the experimental results obtained during the last harvest cycle of the second cropping year. This period was selected to establish the ecophysiological patterns of the alfalfa plants before entering the winter. The morphological variables were the leaf/stem ratio L/S (g DM leaf m-2/ g DM stem m-2), average height of the canopy (cm) and forage yield (t DM ha-1). The radiation variables comprised the incident and transmitted light, zenith angle, probe's spread, and leaf area index (LAI). PAR profile was assessed before cutting using a canopy analyzer (SunScan Canopy Analysis System, Delta-T Devices Ltd., Cambridge, UK).The mean values for the 27 varieties were as follows: LAI of 2.69 (CV=28.76%), canopy height of 41.44 cm (CV=18.41%), leaf/stem ratio of 0.73 (CV=17.19%), and a forage yield of 4.23 t DM ha-1 (CV=21.66%). The relative low coefficients of variation related to the ecophysiological response of alfalfa plants to the abiotic factors suggest a moderate variability between varieties despite their geographical region of origin. A positive correlation was found between canopy height and L/S Ratio (r = 0.52; p<0.01), and with forage yield (r = 0.54; p<0.01). L/S Ratio was positevely correlated with forage dry matter yield (0.63; p<0.001). The interactions between vertical light absorption - absorbing medium - morphological and yield characteristics of the variety have been accurately assessed using the factor analysis. These three factors have explained 79.4% of the variance in the dataset. The obtained indicators are useful to characterize the winter hardiness and to facilitate the selection of the most suitable varieties to be cultivated in equivalent eco-climatic conditions. [ABSTRACT FROM AUTHOR] |
