Effect of various chemical and organic mulch types on soil phyisico-chemical characteristics and qualitative and quantitative yield of saffron in Qaenat region

In order to study the effect of different chemical and organic mulch types on various soil characteristics and qualitative and quantitative yield of saffron (Crocus sativus L.), an experiment was conducted based on randomized complete block design with three replications at Qaen region in during 2018-2019. The experimental treatments were application of various mulch types for weed control (no weed control, hand weeding, transparent polyethylene, black polyethylene, beeswax waste, residues of grape leaf, wheat straw, pomegranate leaf, pistachio leaf, barley straw and saffron corm dunnage). The results showed that all the treatments except black and transparent polyethylene significantly improved the potassium contents of soil compared to hand weeding treatment. Treatments of beeswax waste (0.083%), pistachio leaf (0.081%) and transparent polyethylene (0.080%) included the highest amount of soil nitrogen. The highest amount of carbon (0.838%) and soil organic matter (1.17%) was also observed in beeswax waste mulch treatment. This treatment also led to soil acidification compared to other treatments. Application of all the mulches except transparent polyethylene caused a significant increase in stigmas yield of saffron compared to non-weeding conditions. Beeswax waste and wheat straw had the highest stigma yield (4.89 and 4.32 kg ha-1), respectively; which these increased the stigma yield by 213% and 177% compared to the no weeding treatment. Black polyethylene, pomegranate leaf and grape leaf did not show a significant difference with hand weeding in terms of stigma yield of saffron. The highest amount of safranal, crocin and picrocrocin in saffron was obtained to the black polyethylene mulch treatment. In general, the results confirmed that the application of all the studied mulches with the exception of transparent polyethylene led to improving soil characteristics and saffron yield compared to no weed control treatment and are recommended to farmers.