Purple Nutsedge (Cyperus rotundus L.) Interference and Drought Effect on Proline Accumulation in Soybean (Glycine max L.) Leaves

Generally soybean (Glycine max L.) planted at the end of the rainy season, thereby potentially suffering drought and weed interference simultaneously. Centralized response to various stress in plants cause soybean responses to the multiple stresses will be different when compared to its response to a single stress factor. Proline is a multifunctional amino acid that can act as antioxidants and osmoregulator in tolerance mechanisms of plants against various environmental stresses. The purpose of this research was to studying the multiple stress effect of purple nutsedge (Cyperus rotundus L.) interference and drought treatment to the proline accumulation and cumulative effect character of multiple stress on proline accumulation in the soybean leaves. Designed of this research was factorially using Completely Randomized Design (CRD), i.e., purple nutsedge interference (control, three and six purple nutsedge) and drought (control, mild and severe). The results showed that presence of purple nutsedge interference in the mild drought does not cause an increase of proline accumulation, whereas increased of purple nutsedge interference in the severe drought stress causes increased of proline accumulation. Cumulative effect value of three purple nutsedge interference and mild or severe drought on proline accumulation in soybean leaves less than 100% or cross adaptation, while on six purple nutsedge interference and mild or severe drought more than 100% or cross synergism. This study can be concluded that an increase of proline accumulation in soybean as tolerance mechanism againts purple nutsedge interference and drought.