Effect Of Spraying With Sorbitol And Boron On Growth Characteristics And Oil Percentage In Rapeseed Brassica napus L

The experiment was carried out in a private agricultural field in Baladrooz district, Diyala Governorate, Iraq in the autumn season 2019-2020 to study the effect of spraying with sorbitol and boron on the vegetative growth characteristics and oil percentage of rapeseed. Spraying of boron 50 and 100 mg gave the highest mean in root length 28.59 and 27.83 cm, number of main roots 32.19 and 32.61, number of pods 739.8 and 746.8, and oil percentage 45.08 and 47.43 % compared to boron 0 mg (untreated plants) which reached 26.36 cm, 28.92, 616.5 and 43.24% respectively, while spraying of sorbitol 30 g recorded the highest mean in leaf area 298.14 cm, fresh weight of leaves 13.44 g, dry weight of leaves 1.244 g, root length 29.43 cm, main roots number 34.21, number of pods 746.9 and oil percentage 47.78 % as compared with sorbitol 0 g (untreated plants) which reached 248.50 cm, 10.81 g, 0.962 g, 25.54 cm, 25.49, 602.5 and 41.36% respectively. The interaction of spraying between sorbitol and boron on rapeseed plants resulted in a significant increase in all studied traits, where treatment of boron 100 mg with sorbitol 30 g led to a significant increase in leaf area, fresh weight of leaves, dry weight of leaves and root length, which reached 338.33 cm, 14.99 g, 1.323 g and 30.16 cm respectively, whereas the treatment of boron 100 mg with sorbitol 20 g recorded the highest increase in the number of roots, number of pods and percentage of oil, as it gave 36.50 , 869.2 and 49.67% respectively.

concentrations (0, 10, 20 and 30 g. l -1 ), the second factor was three levels of spraying with boron in the form of boric acid (10.81% B) at concentrations (0, 50 and 100 mg. l -1 ).Cultivation was carried out with three sectors included 12 treatments, distributed randomly inside the each sector. The cultivation was manually by placing the seeds inside the holes and at a depth 1-2 cm on 27/10/2019 by using the seeds of the Pactol variety from the General Company for Agricultural Supplies of the Ministry of Agriculture. The thinning process was carried out after the emergence of seedlings with two leaves, the distance between plants was 4 cm and length of the line was 14 m, while the distance between the lines 1 m and between the experimental units 30 cm.Urea fertilizer N 46% was used as a source of nitrogen, which was added at one time after 20 days of germination, the neutral ultrasol fertilizer (NPK + minor elements) was added after 35 days of germination and high phosphate fertilizer after 40 days of germination. The spraying of plants with sorbitol and boron was carried out three times after 45 days of germination with 21 days between the spraying and another, the first spraying was on 19/12/2019 and the last spraying was on 7/2/2020, the spraying was started with sorbitol, then with boron after 72 hours, Sorbitol or boron was well dissolved in distilled water with the addition of 2-3 drops of liquid soap before spraying.
Studied traits: After 10 days from the last spraying, ten plants were randomly selected from each experimental unit for the following traits, leaf area (cm. leaf -1 ), fresh and dry weight of leaves (g. leaf -1 ), root length (cm. plant -1 ), roots number (root. plant -1 ), pods number (pod. plant -1 ) and oil percentage%, where the oil was extracted from rapeseed using a Soxhlet device, and the estimation was done in the Ministry of Science and Technology laboratories by using a hexane solvent and the percentage of the oil was estimated according to the mentioned method in the American Society of Chemical Analysts [7].
Oil percentage (%) = weight of the beaker before extraction -weight of the beaker after extraction / weight of the sample x 100. Statistical analysis: The results were analyzed using the (SAS) program 2003 and the averages were compared with Duncan's polynomial test at a probability level of 0.05 (4). Table (1) showed that no significant differences between the means of boron levels in leaf area, fresh weight of leaves and dry weight of leaves, while boron 50 and 100 mg was significantly superior in recording the highest mean in root length reached 28.59and 27.83 cm respectively as compared with boron 0 mg which reached 26.36 cm, whereas spraying of sorbitol 30,20 and 10 g was significantly superior in recording the highest mean in leaf area 298. 14

IV.DISCUSSION
Spraying with sorbitol led to an increase in vegetative growth indicators, the reason is attributed to the important role of alcoholic sugars to transport macro and micro nutrients, especially slow-moving elements such as calcium and boron through the phloemto the leaves, roots, stems and branches of plants, which move freely and easily within the plant,transfer of boron and macro and micro nutrients improves physiological and biochemical processes, due to boron and other nutrients are an important factor in the process of photosynthesis and protoplasmic building besides respiration and the synthesis of DNA and RNA for cell division [8,9]. The transfer of macro and micro nutrients leads to an increase in the accumulation of carbohydrates in the leaves, branches and roots, as well as a decrease in the activity of the IAA-oxidase enzyme, thus increasing the auxin content, which leads to the growth activation, and this is reflected positively on the roots growth indicators [10,11]. These results are consistent with [12], when spraying sorbitol on kiwi plants, [13], on the pepper plant, [14] on Strawberry plant and [15] on eggplant.
Spraying boron on the leaves led to an increase in vegetative growth indicators, may be due to the active role of boron in the transfer of nutrients to areas of the active growth, which provided an opportunity for a large increase in Al-Qadisiyah Journal For Agriculture Sciences (QJAS) ISSN : 2618-1479Vol.11, Issue. 2 ,(2021, pp. 17-20 https://jouagr.qu.edu.iq/ nutrients to reach to the leaves, as well as the role of boron in providing and increasing the activity of growth hormones that support chlorophyll and increase the greenness of the plant, all of which leads to an increase in the content of chlorophyll in the plant [16]. The reason may be attributed to the role of boron in building a highly efficient root system in absorbing macro and micro nutrients and increasing their concentration within the plant [17,18]. Boron has a positive role in activating and increasing the effectiveness of growth hormones, especially auxins and cytokinins [19]. Boron also plays an important role in the formation of proteins in plants through the formation of RNA, the work of membranes, nitrogen metabolism and photosynthesis, increasing the amount of carbohydrates and proteins in the leaves [20]. Boron improves physiological and biochemical processes during the activation of meristematic tissues, increasing the elongation and cell division and increasing the production and effectiveness of growth regulators, which reflected positively on the vegetative growth indicators [21].

V.CONCLUSION
According to the findings of the study, Spraying of sorbitol and boron by using different levels separately or combined through the interaction led to an increase in vegetative growth characteristics of Rapeseed.