Could Irrigation and N-fertilization Affect Saffron Yield?

Abstract

Crocus sativus belongs to the Iridaceae family, and it is known as saffron. The aim of this study was to investigate the effect of irrigation and Nfertilization on the produced number and weight of flowers and stigmas. A field experiment was established for the purposes of the study in a clay loam soil of moderately fertile on 2018 while the results concern measurements made in 2019. A split-plot experimental design was used with main factor the irrigation (I1: rainfed, I2: 75% ETo and I3: 100% ETo) and sub-factor the N-fertilization (N1: 0, N2: 40 and N3: 80 kg ha-1 of the 35-0-0) under 9 replications. It was found that 1 kg of dried stigmas is produced through an average of 159.000 flowers. Irrigation was found to be the factor which affected positively the flower number and led to a doubling of stigmas yield, while N-fertilization did not have any statistically significant difference.

Keywords

• saffron
• irrigation
• n-fertilization
• stigmas
• yield

1 Introduction

A perennial aromatic and pharmaceutical crop, member of the Iridaceae family (Arslan et al., 2013) , which has been used as a spice and in traditional medicine is Crocus sativus L. Crocus is worldwide known as saffron and it is cultivated in many hectares in Iran resulting in the increase of farmers income (Mashayekhi et al., 2006; Mollafilabi, 2006) . Saffron is also cultivated in Mediterranean basin and India (Fernandez, 2004) and it prefers mild winter and dry-hot summers. Saffron anthesis period lasts from 10 to 25 days extremely depending on climatic conditions (middle of October till the first ten days of November). Crocus propagation take place only by corms and each plant can reach 20–30 cm height (Mehraj et al., 2015) .

Saffron product is the stigmas of the flowers, and its yield and flower number are depended on irrigation and nutrient supply, on plant density as well as on the day and night site temperature (Gresta et al., 2009; Kumar et al., 2009; Mollafilabi et al., 2013; Koocheki et al., 2014; Koocheki and Seyyedi, 2015; Behdani et al., 2016) . Saffron yield varies according to growing site and it is reported that dried stigmas yield ranges from 2 to 29 kg ha-1 (Alonso et al., 2000) which results in 90-2,175 of fresh flowers (Vignolini et al., 2008; Schmidt et al., 2007; Serrano-Diaz et al., 2012) .

Crocus has many uses. Except for medicine industry, it is used in food industry, in distillery and in coloring (Javadi et al. 2013) . Crocus stigmas is the most expensive worldwide agricultural product worldwide (Gohari et al., 2013; Lim, 2014) , which has also increased cultivation costs due to the requirement of hand labor during its harvest period (Gresta et al., 2008) .

The aim of the current study was to investigate the effect of irrigation and nitrogen fertilization on Crocus sativus L yield during its second growing year. 2

Materials and Methods

A field experiment was established in Neos Skopos, Serres in a clay loam soil of moderately fertile, alkaline and high in phosphorus in August 2018. The results concern the measurements made in October 2019 where the cultivation was in the second growing year.

A split plot experimental design was used with main factor the irrigation (I1: rainfed, I2: 75% ETo and I3: 100% ETo) and sub-factor the n-fertilization (N1: 0, N2: 40 and N3: 80 kg ha-1 of the 35-0-0) under 9 replications (blocks). A basic fertilization with 400 kg ha-1 of the 11-15-15 took place in March for all plots. Water supply was carried out during September-October using a micro-sprinkler irrigation system (Pall Special Spray with characteristics 33L*h-1) and the water quantity was 48 mm and 36 mm for the full irrigated treatments (100% ETo) and the reduced irrigated treatments (75% ETo) respectively.

All measures (number of flowers, fresh flower weight and stigmas fresh and dry weight) were taken during harvest period (20 days harvest period at the end of October till the middle of November for both years) on a daily basis, from the center lines of each plot cutting 1 m2 so as to avoid any border effect, while the rest of the flowers of the plot were moved. Samples were weighed at once (flower and stigmas weight) and then stigmas were air dried.

All measures were analyzed using the statistical package GenStat (7th Edition) and the LSD.05 was used as the test criterion for assessing differences between means (Steel and Torrie, 1982) of the main and/or interaction effects.

3 Results and Discussion

3.1 Number and fresh weight of flowers

As it has been mentioned the soil of the study area is moderately fertile, alkaline and high in phosphorus, which is ideal for crocus cultivation due to its high P-content (Daneshmandi and Seyyedi, 2019) .

In the case of the number of flowers collected during the harvest period, there was found a significant statistical difference was found between the rainfed and the irrigated treatments (Table 1) with the maximum flower number (324 flowers per m2) for the full irrigation. In the case of the N-fertilization and the interaction of irrigation with N-fertilization, no significant statistical differences were found. The higher number per m2 was found in the case of full irrigated and unfertilized treatments (I3N1; Table 1).

As it was expected due to the higher flower number for the irrigated treatments, the fresh weight of the flowers was also statistically significant higher in the same treatments (Table 1). It was also noticed that even if the higher flower number was found in the case of full irrigated and unfertilized treatments (I3N1), the higher fresh weight was found in the case of the full irrigated treatments of the higher Nfertilization (I3N3; Table 1).

3.2 Fresh and dry weight of stigmas

Fresh and dry weight of stigmas was statistically significant higher in the case of irrigated treatments, while N-fertilization did not have statistically significant effect. Maximum dry weight (25.3 kg ha-1) was produced for the full irrigated treatment without N-fertilization (I3N1; Table 1). Furthermore, it was noticed that N-fertilization had a negative effect producing lower dry stigmas yield comparing to the control. Finally, it was found that full irrigation yielded double dry stigmas production compared to rainfed treatments.

Ghanbari et al. (2019), reported that flower number is the most important characteristic affecting stigma yield. Moreover, it is reported that an average of 160.000 saffron flowers are needed to produce 1 kg of dried stigmas (Schmidt et al., 2007; Vignolini et al., 2008) , which is in agreement with the findings of the current study where an average of 159.000 flowers produced 1 kg of dried stigmas. Moreover, the influence of intensive agronomic practices such as irrigation which strongly affects stigmas yield is also reported (Gresta et al., 2009; Koocheki et al., 2014; Behdani et al., 2016) and was also found in the current study.

4 Conclusions

It was found that 1 kg of dried stigmas is produced through an average of 159.000 flowers, which indicates that flower number is the most important feature of Crocus sativus L., and the reason for the high selling price of the saffron product considering the effort it takes to harvest this number of flowers. Irrigation was found to be the factor which affected the flower number positively and led to a doubling of stigmas yield, while N-fertilization did not any have any statistically significant difference. As a general conclusion could be that Crocus sativa L., is a promising perennial crop characterized by satisfactory yield with irrigation being the most crucial factor. Acknowledgments. This work was supported by the Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Greece.

References

1. Alonso , G.L. , Salinas , M.R. , Sánchez-Fernández , M.A. and Garijo , J. ( 2000 ) Physical parameters in controlling saffron quality . Food Sci. Technol. Int., 6 , p. 59 - 65 .

2. Arslan , N. , Ipek , A. , Rahimi , A. and Ipek , G. ( 2013 ) The effects of placement position and corm size of saffron (Crocus sativus L.) on stigma and corm yields in Ankara conditions . J. Herb. Drugs , 4 , p. 1 - 6 .

3. Behdani , M.A. , Al-Ahmadi , M.J. and Fallahi , H.R. ( 2016 ) Biomass partitioning during the life cycle of saffron (Crocus sativus L.) using regression models . J. Crop. Sci. Biotechno ., 19 , p. 71 - 76 .

4. Daneshmandi , M.S. and Seyyedi , S.M. ( 2019 ) Nutrient availability and saffron corms growth affected by composted pistachio residues and commercial poultry manure in a calcareous soil . Commun. Soil Sci. Plan . 50 , p. 1465 - 1475 .

5. Fernandez , J.A. ( 2004 ) Biology, biotechnology and biomedicine of saffron . Recent Research in Development Plant Science , 2 , p. 127 - 159 .

6. Ghanbari , J., khajoei-negad, Gh., Van Ruth , S. and Aghighi , S. ( 2019 ) The possibility for improvement of flowering, corm properties, bioactive compounds, and nutritional regimes . Ind . Crop. Prod., 135 , p. 301 - 310 .

7. Gohari , A.R. , Saeidnia , S. and Mahmoodabadi , M.K. ( 2013 ) An overview on saffron, phytochemicals, and medicinal properties . Pharmacogn. Rev., 7 , p. 61 - 66 .

8. Gresta , F. , Avola , G. , Lombardo , G.M. , Siracusa , L. and Ruberto , G. ( 2009 ) Analysis of flowering, stigmas yield and qualitative traits of saffron (Crocus sativus L.) as affected by environmental conditions . Sci. Hortic-Amsterdam, 119 , p. 320 - 324 .

9. Gresta , F. , Lombardo , G.M. , Siracusa , L. and Ruberto , G. ( 2008 ) Saffron, an alternative crop for sustainable agricultural systems . A review. 28. Springer Verlag/EDP Sciences/INRA . Agron. Sustain. Dev., p. 95 - 112 .

10. Javadi , B. , Sahebkar , A. and Emami , S.A. ( 2013 ) A survey on saffron in major Islamic traditional medicine books . Iran J. Basic Med . Sci., 16 , p. 1 - 11 .

11. Koocheki , A. , Jahani , M. , Tabrizi , L. and Mohammadabadi , A.A. ( 2011 ) Investigation on the effect of biofertilizer, chemical fertilizer and plant density on yield and corm criteria of saffron Crocus sativus L . J. Soil Water , 25 , p. 196 - 206 .

12. Koocheki , A. and Seyyedi , S.M. ( 2015 ) Relationship between nitrogen and phosphorus use efficiency in saffron (Crocus sativus L.) as affected by mother corm size and fertilization . Ind. Crop. Prod., 71 , p. 128 - 137 .

13. Koocheki , A. , Seyyedi , S.M. and Jamshid Eyni , M. ( 2014 ) Irrigation levels and dense planting affect flower yield and phosphorus concentration of saffron corms under semi-arid region of Mashhad, Northeast Iran . Sci. Hortic-Amsterdam, 180 , p. 147 - 155 .

14. Kumar , R. , Singh , V. , Devi , K. , Sharma , M. , Singh , M.K. and Ahuja , P.S. ( 2009 ) State of art of saffron (Crocus sativus L) agronomy, a comprehensive review . Food Rev. Int., 25 , p. 44 - 85 .

15. Lage , M. and Cantrell , C. ( 2009 ) Quantification of saffron (Crocus sativus L.) metabolites crocins, picrocrocin and safranal for quality determination of the spice grown under different environmental Moroccan conditions . Sci. HorticAmsterdam , 121 , p. 366 - 373 .

16. Lim , T.K. ( 2014 ) Edible Medicinal and Non Medicinal Plants . Flowers. Crocus Sativus , vol. 8 . Springer Netherlands, New York, London, pp. 77 - 136 .

17. Mashayekhi , K. , Soltani , A. and Kamkar , B. ( 2006 ) The relationship between corm weight and total flower and leaf number in saffron . In: 2nd International Symposium on saffron Biology and Technology , Mashhad, Iran, 28 - 30 October, pp. 93 - 96 .

18. Mehraj , S.S. , Kamili , A.N. , Bhat , G.A. and Nazir , R. ( 2015 ) Resource allocation in dormant corms of Crocus sativus L. and their heavy metal analysis . Int. J. Adv. Res., 3 , p. 27 - 33 .

19. Mollafilabi , A. ( 2006 ) Saffron production technology . In: Kafi, M. , Koocheki , A. , Rashed Mohassel , H. , Nassiri , M. , (Eds.), Saffron (Crocus sativus) Production and Processing . Science Publishers, New Hampshire, pp. 59 - 78 .

20. Mollafilabi , A. , Koocheki , A. , Moeinerad , H. and Kooshki , L. ( 2013 ) Effect of plant density and weight of corm on yield and yield components of saffron (Crocus sativus L.) under soil, hydroponic and plastic tunnel cultivation . Acta Hortic. , 997 , p. 51 - 58 .

21. Schmidt , M. , Betti , G. , Hensel , A. ( 2007 ) Saffron in phytotherapy: pharmacology and clinical uses . Wien. Med . Wochenschr., 157 , p. 315 - 319 .

22. Serrano-Díaz , J. , Sánchez , A.M. , Maggi , L. , Martínez-Tomé , M. , García-Diz , L. , Murcia , M.A. and Alonso , G.L. ( 2012 ) Increasing the applications of Crocus sativus flowers as natural antioxidants . J. Food Sci. , 77 , p. C1162 - C1168 .

23. Steel , R.G.D. and Torrie , J.H. ( 1982 ) Principles and Procedures of Statistics. A Biometrical Approach , 2nd ed., McGraw-Hill , Inc (eds), 633 .

24. Vignolini , P. , Heimler , D. , Pinelli , P. , Ieri , F. , Sciullo , A. and Romani , A. ( 2008 ) Characterization of by-products of saffron (Crocus sativus L.) production . Nat. Prod. Commun., 3 , p. 1959 - 1962 .