Warm stratification combined with organic manure application enhances seed germination and improves Cycas revoluta growth and development

Cycas revoluta (Sago palm) is one of the widespread ornamental plant, used as an indoor and outdoor plant. Seed propagation is extremely hard and time consuming, given the physical dormancy imposed by hard coat. The use of warm stratification improves seed germination by prompting embryos development. As mean to gain more insight on the beneficial effect of warm treatment on seed germination, histological analysis of warm stratified and untreated embryos was conducted. Our results revealed that warm treatment accelerated embryos development, resulting in a rapid differentiation of embryos’ tissues. α-amylase, GA3 and ABA quantification showed that warm stratified embryos accumulated higher and lower amounts of α-amylase and ABA respectively compared to untreated embryos. Regarding plant development, our results showed that organic manures significantly improved Cycas revoluta growth and development. The best response was recorded with the application of sheep manure. Indeed, sheep manure addition increased plant height, the number of leaves per plant, stip length and width by nearby 188% and 61%, 36% and 17% respectively. In roots, the presence of nodules had been recorded in the three applied treatments and more importantly in the presence of sheep manure. At the physiological level, sheep manure supplementation improved photosynthetic apparatus and nitrogen content in leaves (by 75%), thereby explaining the growth promotion. Taken together, these results underlined the beneficial effect of organic manure on Cycas revoluta growth and development and proposed a new strategy to improve plant growth and development with the use of sheep manure as organic amendment.