عنوان مقاله [English]
Investigating the germination and yield of oilseeds of rapeseed (Brassica napus) and safflower (Carthamus tinctorius) with respect to different levels of seawater salinity in the laboratory
Document Type: Research Paper
Babak Momeni1, Arash Kakoolarimi1*
Department of Agriculture, Payame Noor Unvierstiy, Tehran, Iran
Salinity is one of the most important stresses limiting crop production, which increases with the increase in the cultivated area of watery agriculture. Due to population growth and industrial development, increase in water demand for urban use and the limitation of fresh water resources in the world, it is obvious that in the near future, less water will be allocated for agricultural purposes due to the need for more water to produce products. Agriculture, it is necessary to exploit suitable and cheap water resources in the country, including saline and brackish water. life passion agriculture reduces the pressure on limited fresh water resources. Brackish water, drainage water and sea water can be used to produce beneficial plants resistant to salinity. Although all saline plants have the ability to grow and develop in saline conditions, their tolerance to salinity is not the same. Therefore, they can be divided into three general groups based on their ability to tolerate salinity: a) highly salt-tolerant brackish plants that are able to grow and develop in waters with seawater salinity and higher b) brackish plants that are salt-tolerant brackish waters grow and c) brackish plants with moderate salinity tolerance that grow in relatively brackish waters that are not suitable for common crop plants. Knowing salt-resistant plants and determining their tolerance to salt water will lead to the proper use of coastal lands. Caspian sea water having lower electrical conductivity than other open seas in the world with an average of 18.5 decisiemens/meter equivalent to 12000 ppm can be evaluated as an unlimited water source for use in plant cultivation. Also, due to the presence of many useful salts in the water of the Caspian Sea, including potassium and calcium, compared to drinking water, it can be used as a suitable source of water for growing plants. The average salt of the Caspian Sea is about 13 grams per liter, while it is about 35-45 grams per liter in the open seas and oceans. The Caspian Sea has the lowest amount of Cl− and Na+ and the highest amount of Ca2+ and So42- compared to other open seas, which causes less damage to the physical and chemical properties of the soil. Therefore, the use of Caspian Sea water for agricultural purposes is considered as an option. Safflower (Carthamus tinctorius) is an annual oil plant that is mostly cultivated for oil extraction today. Safflower is considered one of the crop plants relatively resistant to salinity and it is able to produce an acceptable product even in saline conditions. However, its tolerance to salinity at the time of germination and initial seedling growth is low. Rapeseed (Brassica napus) is a one-year plant whose seeds contain 25-55% oil and 18-24% protein. The tolerance threshold of this plant to salinity has been set at 9.7 decisiemens/m and it is considered one of the semi-sensitive to semi-tolerant plants to salinity.
For this research, the seeds of two oil crops, Carthamus tinctorius and Brassica napus, were prepared and cultivated in the fall season of 1401 in the laboratory growth chamber of Payam Noor University in the center of Sari. In order to evaluate the speed and percentage of germination, average daily germination, fresh and dry weight of aerial and underground organs, root and stem length, a factorial experiment in the form of a completely randomized design with three replications and four treatments including normal water (control) and three levels of salinity (10% equal to 1.8 dS/m or 1200 ppm, 25% equal to 4.6 dS/m or 3000 ppm, and 50% equal to 9.2 dS/m or 6000 ppm) of Caspian Sea water (disaggregated based on dissolved solids in the laboratory) was done by culturing in petri dishes in the laboratory. The data was subjected to analysis of variance in Minitab version 18 software and the average comparison of traits in the treatments related to the LSD method was done in Excel software. In this statistical method, the goal was to determine the existence of a significant difference between the respective averages at a significance level of 5%. The quality characteristics of the Caspian sea water and the water used for dilution (the amount of compounds present) which were studied in the water and soil laboratory of Joibar city are listed in table one. Equation 1 was used to calculate the germination percentage and Equation 2 was used to calculate the germination rate. (1) PG = (Ni/N)×100 where Ni is the number of germinated seeds until day i and N is the total number of seeds. (2) RS = ΣSi /Di where RS is the germination rate, Si is the number of germinated seeds per count and Di is the number of days until the i-th count. Equation 3 was used to calculate the average daily germination. (3) MDG = FGP/d where FGP is the percentage of final germination and d is the number of days until reaching the maximum germination.
The results of analysis of variance showed that the studied traits, except the germination speed, in both species under irrigation with different salinity levels of Caspian sea water in different proportions, including normal water (control), 10% ratio equal to 1.8 decisiemens per meter or 1200 ppm, 25% equivalent to 4.6 decisiemens/meter or 3000 ppm, and 50% equivalent to 9.2 decisiemens/meter or 6000 ppm of Caspian sea water were examined, they showed a significant difference at the level of 5% (P≥0.05) (Table 2). The results of germination percentage of two species under salinity levels showed that in safflower, the highest germination percentage was 100% for the control treatments, 10 and 25%, and in rapeseed, the control and 10% treatments had full germination. In this trait, 25% of the two species showed a significant difference in the treatment (Figure 1). The results of the germination rate showed that the safflower species had the highest germination rate in the normal water treatment with a value of 20 and the rapeseed species had the highest germination rate in the control treatment with a value of 12.77. In this trait, the treatments did not show any significant difference. The average daily germination results showed that the safflower species had the highest value in the control treatment with a value of 20% and the highest value in the rapeseed species in the control treatment and 25% with a value of 8.88%. In this trait, there were significant differences in the control and 10% treatments of two species (Figure 2). The stem length of two species under different salinity levels was also investigated. Based on this, the maximum stem length for the safflower species in the control treatment was 7.5 cm, and in the rapeseed species in the 25% treatment, it was 5.68 cm. In this trait, there was a significant difference in the control and 10% treatments of two species (Figure 3). The results of the root length showed that the maximum root length for the 25% treatment was safflower with 17.78 cm and the maximum root length for the rapeseed was 6.95 cm in the 10% treatment, except for the 50% treatment, there were two types of differences in the other treatments. Showed significance together (Figure 4). The highest fresh and dry weight of shoot for safflower species in the control treatment was 0.433 and 0.0251 grams, respectively. The highest fresh and dry weight of shoot for rapeseed species in 10% treatment was 0.128 and 0.0024 grams. They showed two significant differences in this trait in all treatments (Figures 5 and 6). The results of wet and dry root weight showed that safflower had the highest weight in the 10% treatment with 0.108 and 0.0062 grams, respectively, and rapeseed in the control treatment had the highest weight with 0.017 and 0.0011 grams, except in the 50% treatment. percentage, in other treatments showed two significant differences (Figures 7 and 8). According to the results obtained from this research, it was found that the degree of resistance of safflower and rapeseed to salinity in the stages of germination and early seedling growth is different. Ashraf et al. (1997) and Mano and Takeda (1997) stated that the degree of resistance to salinity in the germination stages is different from the later stages of plant development. According to the results, safflower and rapeseed were resistant to salinity stress in the germination stage and resistant to 25% seawater salinity in the seedling stage and did not show resistance to the applied stress in the 50% treatment.