In this paper we will review the saffron growing temperature and saffron cultivation. If you want to know how to grow saffron in pots, you may read this article and if you want to know how to grow saffron commercially you may read this paper.
Saffron growing temperature
Saffron is a subtropical plant and grows well in places with mild winters and hot and dry summers. Saffron is highly resistant to cold, but because its growth period coincides with autumn, winter and early spring, it naturally needs suitable and moderate weather. During the period of dormancy or rest of the plant (summer), rain or irrigation is harmful to it, so its cultivation is not common in Gilan and Mazandaran regions (these regions are humid parts of Iran) and warm regions of the south of the country. Therefore, it is not recommended to grow saffron at this time. Sunny and treeless lands that are also not exposed to cold winds are suitable to grow saffron. However, in some villages of Birjand and Qayen, it is planted under the shade of barberry bushes and almond trees, which are less irrigated in summer.
The maximum temperature of this plant is between 40 to 35 degrees Celsius(saffron growing temperature). At an altitude of 1300 to 2300 meters above sea level, it has shown good performance.
According to a study that was done in Khorasan province, it was shown that the saffron growing temperature has a noticeable effect on flowering the saffron. They came to this conclusion that if the the average temperature of summer and autumn increases by 2 degrees Celsius, flowering of this plant will be significantly delayed. They showed that the saffron growing temperature is not noticeably affected by the change of temperature in day and night. According to the statistics, it was shown that the saffron growing temperature that changes from location to location, highly affects the flowering of saffron. According to a 10-year-research on saffron growing temperature, it has been shown that the production of saffron has decreased over the in increase of the average temperature. According to a simulated model to predict the flowering of saffron, the researchers has estimated that for an increase of 1 degree in saffron growing temperature, the flowering of saffron will be delayed up to 32 days.
The saffron growing temperature and its effect on flowering the saffron has been proved by researchers . The researchers also showed that the optimized saffron growing temperature for flowering is between 17, 25 degrees and if the temperature is more than 30 degrees, the flowering will not take place . The researchers reported that the best flowering was for those saffron bulbs that were kept for 90 to 100 days. The saffron growing temperature for these specimens was 25 degrees. Another group of researchers presented a model to simulate the optimized saffron growing temperature. Using this model they reported that the optimized saffron growing temperature is between 18 to 18.5 degrees and the maximum temperature is 22 degrees.
Suitable soil to grow saffron:
Since saffron bulb stays in the ground for a relatively long time (7-5 years), the soil should be light or a mixture of sand and clay so that the bulb can withstand special regional conditions as well as providing food.
Therefore, to grow saffron and for development of the plant and the production of a good and desirable product, fertile and drained lands without trees with soil (loamy, lemon, clay and sandy) and calcareous with a pH between 7-8 are preferred to saline, poor and wet lands.
When you want to grow saffron you should pay attention that saffron does not produce well in soils that do not have rubble or weeds or rotted organic matter.
How to prepare the Land when you want to grow saffron:
When you want to grow saffron, the preparation of land is of great significance. In preparing the land to grow saffron, it is necessary to pay special attention. First, in suitable time in autumn or winter, the desired land is plowed deeply. If the conditions are not suitable or access to a tractor is not possible, plowing can be done in late spring or early July.
In preparing the land in the traditional way, in early spring, after the spring rains stop, the land is plowed with Iranian plows. After 10-15 days, the land is plowed again. If the land has clods, open the plow and crush the clods by trowel. After two or three weeks, they plow the land again twice in perpendicular directions. Before the third plowing, spread rotten animal manure. By doing this job, the land is partially cleared of weeds as well as the creation of a suitable substrate for cultivation.
In this way, the land is plotted and the length and width of the plots are determined in relation to the slope of the land and the strength of the water. Usually, the width and length of the plots is between 10 *4 to 10 * 100 meters. In mechanized saffron cultivation, the land is plowed deeply in the autumn of the year before planting with a plow. In spring, after the spring rains stop, the soil is plowed moderately. They remove the weeds. In August or September, after spreading 40-80 tons of animal manure and 200 kg of ammonium phosphate, they turn the land into a Faro and prepare it for cultivation. (Of course, nutritionists recommend that about 250 kg of potassium sulfate be mixed with the soil at this stage)
Bulb selection and saffron cultivation time:
When you want to grow saffron, one of the most important factors is the saffron bulb. Construction of new saffron farms is possible and common only with saffron bulbs. Therefore, preparing and selecting high quality saffron bulbs for planting is important in creating and expanding cultivation. Saffron bulbs can be removed from the soil and transferred to another warehouse or farm. Based on the sleeping or resting time of saffron bulbs that lasts from late May to late August, bulbs can be taken out at this distance. It is better to plant the bulbs after removing them from the ground so that the bulbs can be placed in the new soil while continuing to rest. Bulbs should be removed from late August onwards, as some bulbs may be ready for rooting and germination at this time. It can be stored in a cool and dry place with a height of 20-20 cm, but this causes a lack of physiological development of flowers and greatly reduces the yield of the first year of cultivation.
Saffron bulbs can be planted from the time of autumn (early June to mid-October, but it is better to avoid planting bulbs in late July and early August. Because at this time the air and soil is very hot and it is possible that the moisture of the bulb goes away. According to research conducted by the Khorasan Industrial Research Center, the best time to plant is in June.
Type and amount of saffron bulb cultivation:
As mentioned, saffron is propagated by stem tubers, which are full bulb and its size varies from a hazelnut to a walnut. Selected bulbs should be larger, healthier, free of wounds and scratches, and free of any disease.
To grow saffron, saffron bulbs should be disinfected with fungicides such as Sarzan, Tizan and Gramnion, etc. in the ratio of 300-500 grams of for 100 kg of bulbs against fungal diseases before planting. At the time of planting, it is better to separate the scales or dry layer of bulb bottom with some free shell on the bulb so that the bulb absorbs water more easily and germinates faster. The amount of saffron bulb planting varies from 3 to 10 tons per hectare, depending on the size. Planting intervals are usually 30-25 cm on each side.
The number of saffron bulbs selected for planting in each hole is 3 with an average weight of 6 grams per bulb. If the saffron bulbs are planted individually in a row in Faro, at a distance of 8-6 cm from each other, 3 tons of bulbs is needed. If they are planted traditionally and 5 bulbs are used in each hole, the amount of bulb planting will reach 5 tons. It is worth mentioning that in the research, the best bulbs were the bulbs with a size of more than 8 grams.
Saffron bulb planting operation:
To plant saffron bulbs, first dig holes in a row with a shovel and put 3-15 bulbs inside each hole. Depth of saffron bulbs planting can be 15-20 cm and when planting the bulbs, the head should be facing up. Saffron bulbs at a depth of 20 cm in winter are protected from cold and frost and other environmental stresses and in summer from heat.
For planting saffron, 4-5 people participate in such a way that one person digs the holes with a shovel. Two people choose the bulbs in groups of 3 to 5 or 15 and the fourth person puts the bulbs inside the hole. The rest of the people continue to work until the whole land is planted. Finally, the uneven surface of the field is flattened with a shovel or trowel so that the saffron bulbs stick to the soil.
The cultivated land is left in the same way until the autumn irrigation. Before irrigation, about 20-10 tons of completely rotten animal manure is spread on the ground with a shovel.
After planting saffron bulbs, which may last up to the end of September, the next parameter that is of great significance to grow saffron is irrigation. They irrigate the field about 15 to 10 days after planting . In different parts of Khorasan, depending on the climate of the region, saffron irrigation will start from mid-October to the first decade of November. Due to the fact that saffron flowering is somewhat dependent on the initial water, so that the harvesting of saffron does not get difficult, the first water is divided between the parts with a distance of a few days so that the peak flowering period of the parts is not simultaneous.
The first water of saffron is very important and all parts of the land should be watered sufficiently and evenly so that the flowers of one piece come out at the same time. Soil breaking can be done by a an Iranian plow. Breaking the soil makes the flower buds more easily emerge from the soil and grow strong and desirable.
After the first irrigation, 15-20 days later, the first saffron flowers appear. Obviously, the saffron field does not produce significant yields in the first year. From early April until the leaves turn yellow, watering is done every 12-6 days.
It should be noted that after weeding, watering should be delayed so that the weeds are eliminated and do not re-emerge. The last water is effective in enlarging the onion.
As mentioned, after the first irrigation, as soon as the land is plowed, the surface of the field should be broken so that the saffron bulbs are not damaged.
Breaking makes the flowers come out of the soil easily and the animal manure mixes with the soil. In cases where the farmer has not been able to fertilize his land, before watering, the necessary fertilizer can be spread on the soil surface and mixed with the soil with surface plowing, and after this operation, they use the trowel to level the land and make the saffron bulbs stick to the soil.
Weeds reduce yields by competing with the saffron plant for water, nutrients, and sunlight. Therefore, this stage is very important to grow saffron properly. In addition, they may cause disturbances during the planting and harvesting of saffron and carry a number of diseases and insects, especially Nematodes. Field weeding is necessary whenever the weeds grow. The first weeding in the saffron fields is after the second irrigation, and this weeding will eliminate the weeds in the saffron field.
Normally, the first saffron weeding is done after the flowers are harvested and the second, if necessary, is done about a month before the third watering. Regarding chemical control of field weeds, it should be noted that since the effect of these herbicides on the plant has not been tested, the use of chemical herbicides should be avoided as much as possible when you want to grow saffron plants.
Operations to grow saffron more effectively:
Due to the fact that it is not possible to improve the saffron plants through change in breeding, so in order to increase the product efficiency and improve its quantity and quality, the following factors should be considered:
1) The land chosen for planting saffron should be fertile and rich in nutrients and organic.
2) Large and healthy saffron bulbs free from any disease and contamination should be selected for field cultivation.
3) Row work instead of pile work gives better results and simplifies machine operations inside the farm.
4) Use dried and protected saffron bulbs in dry, cool and ventilated conditions.
5) Avoid watering the saffron plant during summer rest.
6) In planting saffron bulbs, be careful that in cold regions it is not 15-20 cm and in temperate regions it is not less than 15-10 cm.
7) Fight weeds as much as possible during summer dormancy.
8) As the saffron bulbs get closer to the soil surface every year, adding a layer equal to 2-3 cm of fertilizer, soil and ash causes more protection of saffron bulbs from environmental stresses and at the same time more nutrients reach the plant.
9) When preparing the land, do not hesitate to add animal fertilizers along with the necessary chemical fertilizers, the amount and time of which have already been mentioned.
10) After irrigation, the soil needs to be broken so that the flowers can easily come out of the soil.
11) Fighting rodents, especially mice, is very important. Any negligence in this regard will destroy the crop and establish mice in the ground.
12) Harvesting flowers in the first hours of the day (4-9 in the morning) when the flowers are buds should be done.
13) Care should be taken in drying the flowers to preserve the pleasant color and aroma of saffron.
14) The best way to dry saffron is the tossing or Spanish drying method, which is done by heater and refractory sieve.
15) Finally, saffron should be stored in containers in metal, tin, wood or glass containers away from light, moisture and heat.
In this article we reviewed the saffron growing temperature, saffron cultivation and planting. (You may also read this paper that tells you how to grow saffron commercially). You can also study this paper and this paper if you to get more information on how to grow saffron. It would be our honor to have your comments regarding our articles.
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