A Comprehensive Look at Nitrogen and Phosphorus Use Efficiency in Saffron (Crocus Sativus L.)

Saffron (Crocus sativus L.) is an annual plant from a biological aspect, but it has a perennial cycle in the field conditions. Cytological impairments such as triploid and self-incompatibility mechanisms are considered as the most important reasons for male-sterility in saffron. Therefore, saffron reproduction is made by meristems tissues and establishment of new daughter corms which are produced by the mother corms. During the growing season, mother corms deteriorate gradually with increasing daughter corms growth. Each daughter corm is considered as a mother corm for replanting in the next growing season. Duo to the life cycle of saffron as a perennial plant in the field conditions, the gradual deterioration of mother corms during the growing season and also the remobilization of nitrogen and phosphorus from aerial part to daughter corms at the end of each growing season, the study of acquisition and use efficiency of nitrogen and phosphorus in saffron is more complicated than other annual or biannual plants. Firstly, the objective of this review article is to describe the nitrogen and phosphorus concentration in aerial parts and daughter corms in saffron. In addition, relevant literature related to the most important strategies for improving nitrogen and phosphorus use efficiency is reviewed. Secondly, the relationship between nitrogen and phosphorus use efficiency in saffron is discussed.