Postharvest exogenous application of various bacterial strains improves the longevity of cut ‘ royal virgin ’ tulip flowers

Over the last few years, global exports of cut flower have grown exponentially, especially in the developing countries which are transforming into diversification strategy to change production of low value and traditional agriculture into high value non-traditional agriculture. One of the major reasons for this paradigm shift is irrational pricing pattern that jeopardize the earning of growers of small land holdings in particular (UNCTAD, 2008). Tulip as spring blooming bulbous plant, possess exorbitant charming buds in different hues and colors that has acquired significant stature in flower trade by gaining the status of a delicacy as a bedding plant in garden landscape (Bukhari, 2005) and as a cut flower. Tulip, being moderately ethylene sensitive has to cope with tepal senescence due to endogenous ethylene production which is a major factor in abridging display life and quality. Although concentration of endogenously produced ethylene in tulips is meager, even this low concentration pacifies rapid senescence of tepals. Senescence is exceptionally a regulated process having an effect on single cells, organs and the whole plant which eventually leads to death during the developmental stages of plant species that enables them to survive (Lim et al., 2007). It may occur at final stage in leaf development and precedes cell death. This process is initiated by chloroplast degeneration, followed by the catabolism of macromolecules, such as nucleic acids, proteins, and lipids and eventually the degradation of mitochondria and nuclei. The released nutrients are transferred to actively growing young leaves and developing fruits and seeds, leading to increased reproductive success (van Doorn and Woltering, 2004; Rogers, 2006). Postharvest life of flowers must be endowed with prolonged freshness to fetch consumer appreciation and acceptance in local as well as global cut flower market (Collier, 1997). They are promptly sensitive, as their degradation starts soon after detachment from parent plant because of induced senescence by ethylene (Figueroa et al., 2005). Plant growth-promoting bacteria are recognized to slow down leaf yellowing and control many factors of cut flowers such as breaking dormancy, delaying senescence and ethylene activity as well as quality flower initiation and improved quality traits (Hunter et al., 2004). Certain bacterial strains are biocontrol agents, capable of killing other microorganism present in the vase solution. Plant growth‐promoting bacteria (PGPB) have Pak. J. Agri. Sci., Vol. 56(1), xxx-xxx; 2019 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI:10.21162/PAKJAS/19.7870 http://www.pakjas.com.pk