E Elahifard - Department of Agronomy and Plant Breeding, Ramin Agriculture and Natural Resources University of Khouzestan, Mollasani, Iran
Abolfazl Derakhshan - Department of Agronomy and Plant Breeding, Ramin Agriculture and Natural Resources University of Khouzestan, Mollasani, Iran

Nulta jute (Corchorus olitorius L.) is one of the most important weeds in southwestern corn and sesame fields in Iran. Experiments were conducted in the laboratory to determine the effects of constant temperatures, drought stress and salinity on seed germination of nulta jute. Based on three- piece segmented model outputs, the base, the lower optimum, the upper optimum, and the maximum temperatures for the germination of nulta jute were estimated to be 15.57, 25.99, 37.79, and 43.67 °C, respectively. Germination percentage of nulta jute seeds was estimated about 88.75%. The response of germination to drought stress was described using the hydrotime model. Based on this model, the hydrotime constant (θH) and the water potential threshold for the start of germination (ᴪb(0)) were 11.85 MP h and -1.13 MPa, respectively. Results showed that base water potential distribution (ᴪb(g)) was skewed to the right (λ=1.51) indicating the major section of seed population with higher base water potential would germinate slowly even in favorable conditions. The response threshold of Nulta jute seeds to inhibit 50% of maximum germination for salinity was 217 mM. The results showed nulta jute could colonize in saline conditions. However, germination was completely inhibited in very low water potential indicating this species tolerant to drought conditions.

Ecology of seed germination; hydrotime; modeling; Weibull