THE EFFECTS OF CHEMICAL AND ORGANIC FERTILIZERS ON SAFFRON FLOWERING

Abstract

The effects of chemical and organic fertilizers on saffron (Crocus sativus) were studied in a field experiment using a complete randomized block design with three replications at ferdowsi university of Mashhad. Fertilizers applied were N, P, K, NP, NK, PK, NPK, cow, sheep and chicken manure. The amount of chemical fertilizer applied were 50, 30, 30, 48, 48, 36, 66 kg/ha for N, P, K, NP, NK, PK, NPK and 12, 8, 4 t/ha for cow, sheep and chicken manures, respectively. The results indicated that number and weight of flower and stigma dry weight were affected by type of fertilizers (p<0.01). The highest flower number was obtained with cow manure and the lowest with N, NK and PK fertilizers. The highest stigma dry weight was obtained with cow manure (0.093 g/m) and lowest with PK treatments (0.035 g/m). The highest flower dry weight was obtained with NPK and the lowest with N and PK application (0.92 and 0.33 g/m), respectively. Stigma dry weight has a stronger correlation with flower number compared to flower dry weight. INTRODUCTION Saffron is a plant with unique characteristics. Total world production of this delicate spice has been estimated 220 tones, 90 percent of which this produced in Iran and 98 percent belongs to Khorasan province (Koocheki, 2003; Mollafilabi, 2003; Shahandeh, 1990). Total acreage of saffron in Iran has been estimated 50,000 hectare. An increasing trend in acreage from the year 1988-2001 has been observed with 3.9 percent increase in cultivated area with an average of 22.4 percent rate of increase (Kafi et al. 2001; Sadeghi et al. 1987). Average yield of saffron in Iran during a period of 25 years has been reported to be 4.7 kg/ha (Kafi et al., 2001; Sadeghi et al., 1987). Since saffron is a perennial crop, it has been adapted to organic fertilizers and hence animal manure plays an important role in this respect. Shahandeh, (1990) found that 16-80 percent of saffron yield is attributed to soil variables and 1-10 percent was related to water availability. He further pointed out that soil chemical criteria such as organic content, available phosphorus, mineral nitrogen, and exchangeable potassium and C/N ratio were the most important factors affecting yield of saffron. Koocheki, (2003) in a survey on 28 farms from 5 major saffron producing areas of Southern Khorasan found that coefficient in manure utilization was 19 percent. Saffron is a low nutrient demanding crop (Rahmati, 2004; Vatanpur-e-Azghadi and Mojtahedi, 2003), however, if above ground is harvested completely, for each kilogram dry biomass, 10.2 kg N, 3.2 kg P and 22.8 kg K is removed from the soil (Shahandeh, 1990). The amount of manure used for saffron in Iran varies from 20-80 tones/ha cow manure (Mollafilabi, 2002; Mollafilabi, 2003). It has been shown (Vatanpur-e-Azghadi and Mojtahedi, 2003) that application of small amount of N and P enhances yield of saffron. However, in some part of Khorasan up to 100 kg/ha ammonium phosphate prior to the first irrigation and 100 kg/ha urea at the time of first weeding is applied (Mollafilabi, 2003). MATERIALS AND METHODS In growing season of 2005-2006 an experiment with a Complete Randomized Proc. II IS on Saffron Bio. and Techno. Eds.: A. Koocheki et al. Acta Hort. 739, ISHS 2007