Cutting-Edge Greenhouse Practices for Better Stigma Yield and Corm Quality of Saffron (Crocus sativus L.)

Muien Qaryouti^1*Abdelrahman Al-Soqeer²Mohamed Ewis ABDELAZIZ³Nazim S. Gruda⁴Saif AlSahly¹Wafa Alrasheed¹Sahar Althobiti⁵Omar Babiker⁶Mahmoud Sharafeldin⁷Wim Voogt⁸

• ¹Research and Innovation Department, The National Research and Development Center for Sustainable Agriculture (Estidamah), Riyadh, Saudi Arabia
• ²Administrative Department, The National Research and Development Center for Sustainable Agriculture (Estidamah), Riyadh, Saudi Arabia
• ³department of vegetable crops, Faculty of Agriculture, Cairo University, Oula, Giza, Egypt
• ⁴Division of Horticultural Sciences, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, North Rhine-Westphalia, Germany
• ⁵Operation facilities department, The National Research and Development Center for Sustainable Agriculture (Estidamah), Riyadh, Saudi Arabia
• ⁶Partnerships and Communication department, The National Research and Development Center for Sustainable Agriculture (Estidamah), Riyadh, Saudi Arabia
• ⁷Medicinal and Aromatic Plants Research Department, Non-Traditional Spices Biotechnology Unit, National Research Centre (Egypt), Cairo, Cairo, Egypt
• ⁸Wageningen Plant Research, Wageningen University and Research, Wageningen, Netherlands

Saffron (Crocus sativus L.) is among the world's most valuable spices, its cultivation in Saudi Arabia is constrained by the high cost of importing quality corms and the challenges posed by extreme open-field conditions. To address these issues, we evaluated saffron production under cooled greenhouse environments. The study investigated three planting densities (200, 100, and 67 corms m⁻²) and two planting depths (8 cm and 13 cm) to determine their effects on plant growth, flower and stigma yields, and new corm development. While a higher density of 200 corms m⁻² maximized total flower and stigma yields per unit area, it reduced flower number, stigma production, and biomass per individual plant. A planting depth of 13 cm consistently reduced daughter corm formation, particularly at the highest planting density. The largest corms and the highest proportion of big corms were obtained at the lowest density of 67 corms m⁻², whereas planting depth had a lesser effect on corm size distribution. Considering the need to balance economic flower yield with the ability to regenerate planting material, we recommend a planting density of 100 corms m⁻² at a depth of 8 cm. This combination achieved an optimal balance between stigma yield and daughter corm production. Implementing these parameters could significantly improve the viability and sustainability of greenhouse-based saffron cultivation in regions facing heat and environmental stress.