Foliar Application of Amino Acid Biostimulants Supplemented with Silicon or Sulfur to Alleviate the Heat Stress in Green Beans

Heat stress is considered as the most important limiting factor for the productivity of beans and the emerging increase in global temperature is estimated to have a strong negative impact on its yield. In this context, the green bean industry is looking for means to mitigate these adverse effects. Foliar application of amino acids-based bi-ostimulants, supplemented with silicon or sulfur, has been reported to have beneficial effects on bean crops to mitigate the effects of various stresses but not of heat stress, yet. Amino16 is a commercial biostimulant with 16 L-amino acids and was used as a basis so that two novel products; Amino16+Si and Amino16+S were further produced. Their efficacy was tested upon foliar application in two consecutive growing seasons (early and late) of green beans. The mitigation of the effects of heat stress in green bean crops was not achieved upon the combined application of amino acids supplemented with sulfur or silicon at several rates. Obviously, higher concentrations of sulfur and silicon are required to induce beneficial effects, and probably through drench application, especially in crops with high sulfur demand, such as beans, while silicon requires another form, other than silicon dioxide, which is not easily absorbed by the plant’s roots.