Saffron responses to summer irrigation and nano zinc oxide

Saffron is an important strategic medicinal plant in Southern Khorasan, Iran. With increasing temperature in the spring, the plant gradually loses its leaves. In order to study the possibility of increasing saffron photosynthesis duration through continuing irrigation in the spring and summer and the effect of nano zinc oxide application, an experiment was conducted in Birjand, Iran. Irrigation treatments and zinc oxide fertilizer treatments were as main plots and sub plots, respectively. Not only continuing irrigation after May had no positive effect on the most measured traits, but also caused a reduction in them, although this reduction was not significant. However, style dry weight reduction under treatment continuing irrigation until August was significant. Zinc oxide application (ordinary and nano) increased significantly fresh flower yield and stigma dry weight, but had no significant effect on flower number and style dry weight. Interaction of irrigation and ZnO fertilizer was not significant in all measured traits. In total, the result showed that continuing irrigation in the spring and summer did not improve saffron yield. Probably the impact of this irrigation method on the corms decay was more than its positive effect on the plant growth. However, more research is needed in this context.