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Relation between corm size and saffron (Crocus sativus L.) flowering

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Abstract

Saffron (Crocus Sativus L.) is a cormose triploid geophyte, unknown in the wild state. It has been cultivated since ancient times for the numerous properties attributed to its stigmatic lobes. Reproduction is only possible through corm propagation, seeds being unknown. The aim of this study is to evaluate the potential saffron flowering in relation to the corm size. The research was carried out in metallic tanks filled with expanded clay and clay soil. Corms coming from Abruzzo and Sardinia were splitted in weight and size classes and tested. At flowering time, plants were harvested and the corm weight and size, flower number per corm, stigma weight were determined. Results confirm a positive correlation between the numbers of flowers per corm and the corm size. The choice of corme size at planting time and the corm enlargement technique are recommended accordingly.
... In another study it was found that corms smaller than 6.9 g did not flower (MacGimpsey et al., 1997) and more recent publications revealed that small corms (below 6 g) usually do not flower in the first year and also exert a negative effect on the flowering of coming years when saffron field is used for several years in one planting time (De Juan et al., 2009;Koocheki et al., 2016aKoocheki et al., , b, 2019a. On the other hand, as the corm size increases there was an increase in flower production De Mastro and Ruta, 1993;De Juan et al., 2009;Poggi et al., 2010;Koocheki et al., 2019aKoocheki et al., , 2019bEsmaeilian et al., 2022). Also, the effect of corm size is not permanent, and it was reported that the higher yield that larger corms can produce can be lost after three years of cultivation (Çavuşoğlu and Erkel, 2009). ...
... Although saffron yield is influenced by many agronomic, biological, and environmental factors that can exert a significant influence on production, production is strictly influenced by factors such as corm storage conditions (De Mastro and Ruta, 1993;Gresta et al., 2008 a,b), climatic conditions (Tammaro, 1999), sowing time (Gresta et al., 2008b), cultural techniques (annual or perennial), crop management (irrigation, fertilization, and weed control), and diseases (Gresta et al., 2008a). Since saffron remains in the same fields for several years, the growth and yield are affected by variations in the corm size distribution of the daughter corm populations in different years. ...
... It was found that flowering duration fluctuated and is crucial for the crop as the highest stigma yield was found during the fourth year. Several studies have examined the effects of corm size and planting density separately or for less than six years (growing seasons) (Plessner et al., 1989;Negbi et al., 1989;De Mastro and Ruta, 1993;Tammaro, 1999;Gresta et al., 2008b;Çavuşoğlu and Erkel, 2009;De Juan et al., 2009;Kumar et al., 2009;Renau-Morata et al., 2012;Koocheki et al., 2019aKoocheki et al., , 2019b. However, no studies have determined the effect of corm size at different planting densities for the entire six years that a saffron crop can last as reported in the present study. ...
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The effect of the corm size of saffron (Crocus sativus L.) and the planting density was determined on a field study for six years. The objective of the present study was to determine the impact of the corm size and planting density on flower and stigma yields. Two corm sizes were used: corms with a diameter up to 2.5 cm and corms with a diameter greater than 2.5 cm, and five planting density: 22, 27, 33, 44 and 67 corms/m2 with planting distances 30, 25, 20, 15 and 10 cm on the plant row, respectively. The results showed that the year (growing season) and the interaction of year (growing season) with corm size affected all the characteristics that were studied. Over the six-year study period, there was a gradual increase in flowering from the first to the third year, followed by a decline in the fifth and sixth years. The yield of larger corms (greater than 2.5 cm) was higher during the first three years, while smaller corms (less than 2.5 cm) produced higher yields in the fourth through sixth years. On the contrary, the planting density, did not significantly affect the characteristics studied over the six years of cultivation and therefore did not affect the stigma yield of saffron. Therefore, corm size together with the environment are important factors that can affect the productivity and the longevity of the crop and should be considered when planting a new saffron cultivation.
... In larger corms, cell division and, consequently, leaf growth occur somewhat earlier than in smaller ones. Therefore, saffron plants obtained from larger corms produce more leaf area compared with those from smaller corms (De-Maastro and Ruta, 1993). Earlier growth and larger leaf positively affect the photosynthetate accumulation, finally resulting in larger daughter corms at the end of the growing season (Molina et al., 2005b). ...
Article
ADDITIONAL INDEX WORDS. controlled environment, Crocus sativus, indoor culture, soilless culture SUMMARY. Hydroponics is a promising method for cultivation of saffron (Crocus sativus). In this study, saffron corms were sprouted using a gradual decrease in air temperature, and they were cultivated hydroponically in either perlite or volcanic rock for 24 weeks. A nutrient solution was supplied using either an ebb-and-flow system or continuous immersion. First blooming was observed 29 days after transplantation. Among flowering traits, only the stigma length was significantly influenced by the type of hydroponic system. Saffron plants displayed better growth parameters, a higher photosynthetic rate and stomatal conductance (g S), as well as daughter corm (cormlet) production under the continuous immersion system, in comparison with the ebb-and-flow system. Small corms (22-25 mm diameter) did not bloom, and the emergence of flowers increased with corm size. Plant growth and photosynthetic parameters, as well as cormlet production, significantly increased with corm size. We obtained the highest stigma yield [number of flowers (1.9), stigma length (39.4 mm), stigma fresh (42.8 mg), and dry weight (5.3 mg)] and cormlet yield [number of cormlets (5.7), average corm diameter (25 mm), and fresh weight (6.4 g)] using mother corms sized $32 mm diameter grown hydroponically in the volcanic rock-based continuous immersion system.
... In larger corms, cell division and, consequently, leaf growth occur somewhat earlier than in smaller ones. Therefore, saffron plants obtained from larger corms produce more leaf area compared with those from smaller corms (De-Maastro and Ruta, 1993). Earlier growth and larger leaf positively affect the photosynthetate accumulation, finally resulting in larger daughter corms at the end of the growing season (Molina et al., 2005b). ...
Article
Full-text available
Hydroponics is a promising method for cultivation of saffron (Crocus sativus). In this study, saffron corms were sprouted using a gradual decrease in air temperature, and they were cultivated hydroponically in either perlite or volcanic rock for 24 weeks. A nutrient solution was supplied using either an ebband-flow system or continuous immersion. First blooming was observed 29 days after transplantation. Among flowering traits, only the stigma length was significantly influenced by the type of hydroponic system. Saffron plants displayed better growth parameters, a higher photosynthetic rate and stomatal conductance (gS), as well as daughter corm (cormlet) production under the continuous immersion system, in comparison with the ebb-and-flow system. Small corms (22–25 mm diameter) did not bloom, and the emergence of flowers increased with corm size. Plant growth and photosynthetic parameters, as well as cormlet production, significantly increased with corm size. We obtained the highest stigma yield [number of flowers (1.9), stigma length (39.4 mm), stigma fresh (42.8 mg), and dry weight (5.3 mg)] and cormlet yield [number of cormlets (5.7), average corm diameter (25 mm), and fresh weight (6.4 g)] using mother corms sized $32 mm diameter grown hydroponically in the volcanic rock–based continuous immersion system.
... According to other authors (De Mastro and Ruta, 1993;Gresta et al., 2008), stigma yield was influenced positively by corm dimension. Moreover, as reported by Macchia et al. (2013), saffron production was influenced by corm geographical origin too. ...
... Besides field age, agronomic management and environmental factors also influence flower productivity and yield. Research showed that larger corm size and earlier sowing time positively affect stigma production (De Mastro & Ruta, 1993;Gresta et al., 2008). Irrigation shortly before saffron flowering influences the anthesis duration, flower density, and stigma quality. ...
Article
Saffron (Crocus sativus L.) is the most expensive spice worldwide and is predominantly produced in the Khorasan Province situated in north-east Iran. Climatic shifts and lowering groundwater tables negatively affect saffron yields in this region, which are determined by environmental factors, agronomical practices, and crop age. Nonetheless, spatially explicit information on changes in saffron cultivation is scarce, underlining a need for better monitoring tools. This study aims to evaluate the utility of Sentinel-2 (S2) time series in accurately mapping saffron fields and their ages (i.e., how many years saffron was cultivated in a field), based on its unique phenology. To separate saffron from other land covers, we first derived 252 spectral-temporal features by calculating 21 spectral features (10 individual bands plus 11 vegetation indices) for each of the 12 months. A Random Forest (RF) algorithm was then used in combination with field data to retain only features of high importance for saffron classification. These features comprised vegetation indices that incorporated spectral information from red, and near- and shortwave infrared bands during the phenological phases of the rapid green-up (February to March) and the dormant period (August to October). The RF classifier resulted in a saffron map for the year 2019 with a high classification accuracy based on these features. Compared against an independent in-situ saffron field dataset, 87.6% of the existing fields were correctly classified as saffron. To assess saffron field ages, we analysed the spectral separability of different age groups using the NDVI time series. We found that NDVI levels between December and May allowed for effectively separating 1st, 2nd, 3rd, 4th-6th, and 7th-8th year saffron fields. An RF-based classification of field ages resulted in an overall accuracy of 86.8%. This study demonstrated that S2 time series data allow for accurately mapping saffron fields and their age groups. Our findings provide a solid basis for mapping saffron across larger areas and for monitoring changes in saffron distribution. Such information is crucial for understanding how anthropogenic and climate change impacts will affect the future of saffron cultivation.
... Nutrient reserves present in the mother corms have an effect on saffron growth, particularly during early growth stages. The size of corm generally varies from 1 to 20 g, and is directly related to flowering and number of flowers produced [118,119]. Small sized corms (<6 g), either fail to flower or have limited potential of flowering [120]. Optimum corm size (8 g) must be preferred for rising of saffron crops, as it directly enhances the yield and production of daughter corms. ...
Article
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Saffron, comprising of dried stigmas of the plant known as Crocus sativus, is one of the most important and scantly cultivated agricultural products. It has been used as a precious spice for the last at least 3500 years. Due to its numerous medicinal qualities and pharmacological applications, it is considered as a “golden condiment”, and its demand and consumptions has risen over a period of time. Although efforts are continuously being made to enhance the productivity in the traditional areas and promote the cultivation of saffron in the newer areas, there are several constraints hindering these efforts. Prevalence of corm rot is one such limiting factor which results in the reduction in saffron production and decline in the area under its cultivation. The disease not only reduces the yield substantially, but also adversely affects the production of daughter corms. Complete understanding and knowledge about the disease is still lacking due to the inadequate information about its etiology and epidemiology. Moreover, due to the non-availability of resistant genotypes and lack of improved cultural practices, presently no effective and sustainable management strategies are available. This review article gives an overall account of the history and impact of saffron corm rot, its present status, yield losses caused by it, dynamics of the pathogens associated with the disease, their survival and dispersal, factors influencing disease intensity, epidemiology and sustainable management strategies. As comprehensive information on the disease is presently not available, an attempt has been made to review the current knowledge regarding corm rot of saffron. The information about the disease discussed here can eventually be beneficial for the growers, students, researchers, plant protection organizations, development departments, extension workers, policy makers, government agencies and public organizations.
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The absence of low temperature treatment leads to slow shoot growth in spring and results in flowering and various physiological disorders. Among several naturally occurring environmental factors, temperature is considered to play a predominant role in controlling proper growth and flowering in geophytes. Most of them require a “cold-warm” sequence to complete their annual cycle. Exposure of corms to vernalization is the most important physiological phenomenon and ecological factor governing variation of the vegetative apex into the reproductive one in saffron. Results findings showed that among different vernalization treatments, minimum days to emergence, highest emergence percentage, number of leaves plant-1, maximum leaf length (cm), number of cormels plant-1 were observed in saffron plants when corms were treated for 16 days vernalization while maximum number of sprouts corm-1, plant height (cm) and cormels weight (g) were recorded in saffron corms treated with 12 days vernalization. Among different corm sizes, minimum days to emergence, maximum emergence percentage, number of sprouts corm-1, average plant height (cm), number of leaves plant-1, leaf length (cm), number of cormels plant-1 and highest cormels weight plant-1 (g) were noticed in larger corm size (11g). It is concluded from the research findings that saffron corms of larger size when treated for 16 days vernalization could give better production.
Article
The influence of phosphorus and planting distance on corm production of Crocus sativus was studied at the Ornamental Horticulture Farm of Department of Horticulture, Kabul University during 2019-2020. Four different phosphorus (P) doses i.e. 0, 20, 40 and 60 kg ha-1 were applied to five different densities viz. 242, 107, 54, 30 and 20 plants m-2. The experiment was laid out in Randomized Complete Block Design (RCBD) with split plot arrangement. P effect was largely non-significant, whereas planting densities had considerable effects. The increase in corm number m-2 with increase in plant density means that more corms were planted per unit area. Hence more production in terms of corm number was obtained from the densely planted areas. However, as we know crocus is a perennial crop and the corms are left in soil to grow for several years. Maximum days to sprouting (29.8), number of cormels m-2 (441.7), number of corm m-2 (371.1) were produced by 242 plants m-2, while minimum in these were recorded at 20 plants m-2 density. Number of cormels (2.5), cormel weight (1.6 g), number of corms (2.0), corm weight (11.1 g), corm volume (10.7 ml) and corm diameter (3.1 cm) were produced by plants at 20 m-2 densities, while minimum values for the above parameters were noted in 242 plants m-2. The interaction of phosphorus doses and planting distance was significant for some parameters. A comparison of means values for plant densities revealed that maximum corm volume (10.7 ml) was produced by plants at the lowest density (20 plants m-2), while it was minimum (8.8 ml) at the highest density (242 plants m-2).
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The present study was conducted to evaluate the influence of gibberellic acid (25, 50, 100, and 200 ppm) applied on saffron corms previously harvested during different periods (March, June, and before planting) on the growth and the quantitative and qualitative yield of saffron (Crocus sativus L.). The study was carried out in the field during the 2016-2017 and 2017-2018 seasons in the experimental station of the Faculty of Sciences of Oujda (Morocco). The measured parameters correspond, on the one hand, to morphometric measurements and to the determination of the saffron stigma yield and, on the other hand, to the evaluation of the quality of the spice. The results showed that almost all the parameters studied were significantly affected by the factors considered. The treatment of corms just before planting with concentrations of 100 and 200 ppm GA3 showed the highest flower and leaf appearance rate and the highest leaf length and surface area. Moreover, the application of GA3 during the month of March gave the best results in terms of stigmata yield, percentage of large-diameter daughter corms, and the ratio of the number of flowers produced to the total weight of corms. The results of the coefficient of corm propagation revealed that the application of gibberellin during any period improved this coefficient compared to the control. The results indicated that the application of GA3 with concentrations above 25 ppm can improve the growth of saffron and increase its yield under the semiarid climatic conditions of eastern Morocco.
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Among all environmental factors, the temperature is considered one of the key elements that control the growth and development of saffron. This study was undertaken to investigate the effect of thermal forcing of corms on saffron growth and development. To this end, mother corms were collected at four different periods: late March (T2) , mid-April (T3) , late April (T4), and after leaf senescence (Control, T1) . The corms of each period were then pretreated at three successive temperature levels: at 25 °C for 2 weeks, at 15 °C for 2 weeks and finally at 4 °C for 12 weeks. The results showed that the thermal pretreatment of corms had a significant effect on some saffron parameters. The flowers of the corms that underwent thermal treatment were later than those of the control. Similarly, the flower numbers and stigma yield were negatively affected by thermal forcing of corms. Overall, the thermal forcing of corms under the proposed regime was unfavorable for the growth and development of saffron.
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