The Effect of Corm Size and Different Harvesting Time on Saffron (Crocus sativus L.) Regeneration

Saffron (Crocus sativus L.) is belonging to Iridaceae family. Genus Crocus has about 80 species and 32 of them exist in Flora of Turkey. 18 species are endemic for Turkey. About 30 of Crocus species are cultivated as ornamental plant. The corms of some Crocus species get flowering in autumn are used as food in Anatolia. Saffron is one of the oldest plants and its history extends to B.C. 3000. Its wild species is not known however, researches made indicated that it resembles with Crocus cartwringhtianus (Caiola et al., 2004; Zubor et al., 2004). Saffron’s stigma is used as vegetable dye, spice and medicine industry. In middle ages, it had a big importance as dye and it was used for dying cloth and food materials. It is used also in folk medicine (Arslan, 1986; Deo, 2003; Erdemir, 2001; Forsyth, 2000; Gümüşsuyu, 2002; Koyuncu and Güvenç, 1997; Pahlow, 1989).

Saffron is cultivated in many countries such as Iran, Spain, China, Indian, Greece, Morocco, Nepal, Australia, New Zealand, Egypt, Mexico, Italy. Iran is the most important producer country in the world and its production amount is 150-200 tons per year. In addition, it takes place in first rows of word saffron trade.

Saffron was one of the important cultivated plants in the period of Ottoman Empire. The most of the saffron production was being exporting. Its production has been decreased by the time. In today, it is cultivated in limited area of Safranbolu province (Arslan, 1984; Baytop, 1963). Saffron is harvested traditionally every three years in Turkey and than transplanted without any classification. Harvesting changes in the world from every year to every seven years. In recent years, some studies have been made in order to progress saffron cultivation in Turkey. In these studies, the biggest handicap is the lack of corm material. Saffron is the triploid plant so, it is reproduced vegetatively (Arslan, 1997).

This study was carried out in order to determine the effects of corm size and harvesting every year and every two year on saffron propagation.
MATERIALS AND METHODS

Saffron corms obtained from Agricultural Directory of Karabük Province were used as the study material. Corms were classified according to corm perimeter as 3.00-4.99 cm, 5.00-6.99 cm, 7.00-8.99 cm and 9.00-11.00 cm.

Corm sowing was done at the date of 23 September 2004, using randomized complete block, split-plot design with three replications. Planting was performed as 20 x 10 cm of plant spacing with harvesting years as main plots and corm sizes as subplots. Each subplot consisted of 2 rows with 40 corms due to lack of corm material. No fertilization and irrigation were applied to the experiment. The flowering harvesting was done at the beginning of November of 2004. At the beginning of June in 2005, corms were harvested in the plots of every harvesting year and than they planted in September of same year. The results were subjected to analyze of variance and differences among average values were determined statistically.
RESULTS

Corm Number per Plant

The value of corm number per plant regarding different harvesting times and corm size are presented in Table 1. There was no significant difference between harvesting every year and harvesting per two years while, corm number per plant was found important statistically among corm sizes. Average corm number ranged between 1.10 (3.00-4.99 cm) and 8.34 (9.00-11.00 cm). Corm number per plant increased sharply with increasing of corm perimeter. Larger corms supplied more corm numbers in harvesting every year than smaller corms. Corm number decreased clearly with harvesting every year in the corms with 3.00-4.99 cm of perimeter because of remaining the smaller corms in the soil.

Corm yield obtained from different harvesting times are shown in Table 2. As shown in Table 1, corm yield was affected statistically both harvesting time and corm size. Interaction between two factors was significant. Average corm yield was 805.8 kg/da in every year harvesting whereas, it was 462.4 kg/d in every two years harvesting (10 d = 1 ha). Corm yield with respect to corm perimeter changed between 103.3 kg/da (3.00-4.99 cm) and 1605.2 kg/d (9.00-11.00 cm). With respect to correlation, the highest yield (2076.1 kg/d) was recorded from the combination of every year harvesting and 9.00-11.00 cm of perimeter while the lowest yield (98.3 kg/d) was obtained from the combination of harvesting per two years and 3.00-4.99 cm of perimeter. In both harvesting times, yield differences were higher in larger corms than the smaller corms.

As shown in Table 3, used corm material affected yield and yield changing ratio, differently. The amount of used corm varied from 90 kg/da to 520 kg/d. It used corm is hundred, corm yield changed between 109.2 % and 399.2 %. The results of study indicated that minimum yield increasing was recorded from small corms.

Variation of Corm Sizes after Harvesting

The variation of corm size harvesting in different times are shown in Table 4. Harvested corm perimeters were smaller than the used corm as a material. 10.4 % of every year harvesting corms in 9.00-11.00 cm was same with material corms. Any corm was not obtained from harvesting per two years in 9.00-11.00 cm of corms. In both harvesting times, the ratio of 3.00-4.99 cm perimeters corms increased depending on decreasing of corm perimeter.

Flowering ratio and stigma yield are presented in Table 5. As shown in Table 5, flowering was seen in perimeter of 7.00-8.99 cm and 9.00-11.00 cm corms in both harvesting times. In 2004, flowering ratio was same (1.7 %) in 7.00-8.99 cm perimeter of corm in both harvesting times while it was different (61.4 % and 55.0 %) in 9.00-11.00 cm perimeter of corm. In 2005, significant differences of flowering ratio were occurred in 7.00-8.99 cm and 9.00-11.00 cm perimeters of corms in both harvesting years. In 9.00-11.00 cm perimeter of corm, flowering ratio was 128.0 % in every year harvesting where as it was 73.0 % in harvesting per two years. For this reason, significant differences in stigma yield were recorded between harvesting times and the best result was obtained from 9.00-11.00 cm perimeter of corm in every year harvesting as 448.0 g/d.

There are a lot of literatures indicate that there is a positive correlation between corm size and regenerated corm number is saffron (Arslan, 1997; Çavuşoğlu and Erkel, 2005; Deo, 2003; Gümüşsuyu, 2002; Mc Gimpsey et al., 1997; Vurdu et al., 2002; Vurdu and Güneş, 2004). New regenerated corm number increases when used corm perimeter increases. But this increasing rate is low in small corms. No more studies were found in saffron yield. Mc Gimpsey et al. (1997) obtained 10.540 kg/da of corm yield five years after planting using 29 g corms as the seeding material. Also, corm yield is affected by planting density, some agricultural practices and so on. Regarding corm number per plant, there is no important difference in yield between both harvesting times. But the rate of bigger corm size was more in every harvesting year. As shown in Table 4, regenerated corms were smaller than the seeding materials. Mc Gimpsey et al. (1997) recorded average 6.3 g of corms after five years from average 29 g corm of materials. This result is the similar with the present study.

Stigma yield increases in second year as reported in some literatures. But it was some more in every year harvesting in our study on the contrary. Hosseini et al. (2004) found different results about stigma yield in different studies. In harvesting per two years, soil hardening can be resulted stigma yield decreasing besides no fertilization and irrigation in our study.

The results of our study indicate that both stigma yield and corm number were affected by corm size. In our country, saffron corms are planted without classification. This study showed that corm classification must be necessary before planting. Big corms should be used in order to get more yield and regenerated corms. Small corms must be planted in different place in order to enlarge. Every year harvesting can be made in case large corm uses.

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Table 1. The corm number per plant in harvesting every year and per two years

Table 2. The corm yield in harvesting every year and harvesting per two years (kg/da)

Table 3. Yield changing in different harvesting times and corm sizes

Table 4. The variation of corm sizes after harvesting (%)

Table 5. The ratio of flowering (%) and yield of stigma (g/d)