ORIGINAL ARTICLE

Performance of Sesbania–Sunflower under Different Cropping Systems using ¹⁵N and ¹³C

A field experiment on sesbania (ses) and sunflower (sun) plants grown in monocropping and intercropping systems (1ses:1sun; 1ses:2sun, and 2ses:1sun, row ratio) was conducted to evaluate growth and N₂-fixation using ¹³C and ¹⁵N natural abundance techniques. The results showed that 1ses:1sun surpassed the other treatments in terms of nitrogen (N) and dry matter yields (DM). However, 1ses:2sun gave the highest seed and oil production and showed the greatest N₂-fixation. Sesbania plants in the 1ses:2sun fixed almost identical amounts of N₂ in mono and intercropping systems. Moreover, soil N-uptake was the lowest among other treatments. These results give an advantage to the 1ses:2sun treatment over other treatments in terms of soil N consumption and N₂ fixation to meet sesbania's N requirements. Nevertheless, 2ses:1sun seemed to be an inappropriate treatment. On the other hand, it could be suggested from ‰D¹³C data that plants in the intercropping systems appeared not to be subjected to any abiotic stress during the growing period.