INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY 1560–8530/2007/09–6–868–872 http://www.fspublishers.org Incorporation of Polyamines in the Priming Media Enhances the Germination and Early Seedling Growth in Hybrid Sunflower (Helianthus annuus L.) M. FAROOQ 1 , SHAHZAD M.A. BASRA†, M. HUSSAIN, H. REHMAN† AND B.A. SALEEM‡ Department of Agronomy, †Crop Physiology and ‡Institute of Horticultural Sciences, University of Agriculture, Faisalabad- 38040, Pakistan 1 Corresponding author’s e-mail: farooqcp@gmail.com ABSTRACT A laboratory study was conducted to evaluate the benefits (if any) associated with the incorporation of polyamines in the priming media for hybrid sunflower achene priming. Achenes were subjected to hydropriming for 24 h and in the solutions containing 10 mg L -1 spermidine and putrescine for 24 h. All the achene priming treatments resulted in improved germination and early seedling growth. Priming in spermidine solution resulted in lower time to start emergence, time taken 50% emergence and mean emergence time and energy of emergence, emergence index, root and shoot length and seedling fresh and dry weight than all other treatments including control. However, hydroprimed achenes resulted in maximum final emergence and leaf score; while priming in putrescine solution resulted in maximum number of roots. Key Words: Priming; Sunflower; Polyamines; Germination; Achenes INTRODUCTION Sunflower (Helianthus annuus L.) is one of the most important oil seed crops in Pakistan. It is a short duration crop (90-110 days), can be grown twice in a year. It is fully fit in our cropping system and can be grown without causing displacement of any major crop. One of the major obstacles to high yield and production is the lack of synchronized crop establishment in sunflower (Mwale et al., 2003). The seeds are occasionally sown in seedbeds having unfavorable moisture, because of the lack of rainfall at sowing time, results in poor and unsynchronized seedling emergence (Mwale et al., 2003). In recent years, a lot of work has been done on the invigoration of seeds to improve the germination rate and uniformity of growth and reduce the emergence time of many vegetables and some field crops (Basra et al., 2003). Furthermore, the invigoration persists under less than optimum conditions such as salinity (Muhyaddin & Weibe, 1989), excessively high and low temperature (Pill & Finch- savage, 1988; Bradford et al., 1990). Seed invigoration treatments such as hydropriming, osmopriming, hardening, matripriming and growth regulators have been successfully employed in many parts of the world. Seed priming has been successfully demonstrated to improve germination and emergence in many crops, particularly seeds of vegetables and small seeded grasses (Heydecker & Coolbaer, 1977; Bradford, 1986). The beneficial effects of priming have also been demonstrated for many field crops such as wheat, sugar beet, maize, soybean and sunflower (Parera & Cantliffe, 1994; Singh, 1995; Khajeh-Hosseini et al., 2003; Sadeghian & Yavari, 2004). Dharmalingam and Basu (1990) reported beneficial effect of a hydration-dehydration seed treatment on germination of sunflower. Rao et al. (1987) reported that primed Brassica seeds may reduce the risk of poor stand establishment in cold and moist soils. However, Singh and Rao (1993) stated that KNO 3 effectively improved germination, seedling growth and seedling vigor index of the seeds of sunflower varieties with low germination. Polyamines are known to have profound effects on plant growth and development (Watson & Malmberg, 1998). Polyamines, being cationic in nature, can associate with anionic components of the membrane such as phospholipids thereby stabilizing the bilayer surface and retarding membrane deterioration under stress conditions (Basra et al., 1994). There is now conclusive evidence that polyamines (PAs) accumulate in plants and are involved in their protection against various environmental stresses (Bouchereau et al., 1999; He et al., 2002). Even if polyamines accumulate, this does not mean that they are involved in stress protection, especially as the role of polyamines may depend on their cellular localization and whether they are free, bound to proteins or conjugated to phenolic acids (Bouchereau et al., 1999). However, there are many reports that indicate that stress tolerance of plants is correlated with their capacity to enhance the synthesis of PAs under stress (Bouchereau et al., 1999; Kasukabe et al., 2004). Of the different polyamines, spermidine (Spd) is more closely associated with stress tolerance of plants than are putrescine (Put) and spermine (Spm) (Bouchereau et al., 1999; He et al., 2002; Martı´nez-Téllez et al., 2002).