Effect of Foliar Spraying with Boron and Brassinolide on the Growth and Flowering of Gladiolus

Experiments were run in a greenhouse at the University of Baghdad’s College of Agricultural Engineering Sciences to examine the impact of foliar spraying with boron and brassinolide on gladiolus development and blooming. Using a two-factor randomized complete block design (RCBD), a factorial experiment was conducted. The treatment with B4bl3 showed the greatest improvement in terms of plant height (90.75 cm), number of leaves (10.67 leaves), leaf area (125.83)dm2, chlorophyll content in leaves (54.33) mg.g-1, dry weight (58.17 g), number of corms (7.33 corms), corm diameter (4.800 cm), and corm weight (58.17 g). The number of flowers produced (9.67) and the length of time they last in a vase (14.67) were also improved upon. The flowering period was shortened from 75.00 days to 14.67 days.


Introduction
Gladiolus hybrida is considered one of the most important bulbs whose flowers are suitable for harvesting because it has a appropriate vase life, a strong and long flower holder, and a short growth period [1].It is one of the summer annual bulbs and can be produced throughout the year by providing appropriate environmental conditions in protected environments.It belongs to the Iridaceae, and is native to South Africa and southern Europe [2].Gladiolus flowers are suitable for commercial picking, as they are used in making various arrangements and for all occasions, in addition to exporting them to global markets, thus increasing the revenues of the country's national economy [3,4].The gladiolus flower is one of the most famous flowers of commercially grown ornamental bulbs.In order to improve the quality of flowers both while they are still on the plant and in the vase after they have been harvested, it is essential to increase the flower yield through the use of cutting-edge techniques, a variety of fertilization methods, and optimal concentrations of nutrients, because the nutrients A major role in the metabolic processes within the plant, the building of the cell wall, photosynthesis, the formation of chlorophyll pigment, the respiration process, and the various enzymatic activities [5,6].Brassinosteroids (BRS) is a plant hormone that affects several processes that contribute to plant development, including seed germination, flowering and senescence, and helps the plant to withstand abiotic stresses [7].
Indicated [8] Lakshmi, 2021 showed spraying at a concentration of 1 ppm boosted vegetative development markers in tuberose, including early flowering and improved flower quality, leaf area, and the quantity of leaves.Boron is a micronutrient, but it plays a crucial role in a plant's development and health.The exact amount is dependent on the plant's demands.A plant's physiological health can be compromised by a lack of this element.It's also necessary for making gibberellins, which are hormones.Protein synthesis, sugar accumulation, and vitamin C accumulation are all dependent on it.It plays a role in the synthesis of auxin (IAA).The expansion of a plant's height, number of leaves, stem diameter, and bloom diameter are all influenced by this factor [9][10][11].Indicated [5] found spraying boron onto a Gladiolus plant improved the plant's height and leaf area, which in turn led to an increase in the quantity of flowers, the quality of those blooms, the length of time they flowered, and the onset of flowering.The purpose of this research is to identify the optimal concentrations of boron and brassinolides for optimizing vegetative and floral growth in Gladiolus bulbs, as well as to characterize the relationship between these two elements.

Materials and Methods
After performing all field operations, including soil preparation, plowing, leveling, smoothing, and dividing it into 5 sections, the experiment was carried out in the greenhouse of the Department of Horticulture and Landscape Engineering at the College of Agricultural Engineering Sciences, University of Baghdad, Iraq, to study the effect of spraying boron and brassinolide and the interaction of them on the growth and flowering of the Gladiolus plant.On 10/15/2022, the gladiolus corms were planted in the soil immediately on both sides of the drip pipes, with a space of 40 cm between one corm and another, and the bush was regulated with pesticides and fungicides.The experiment was carried out as a factorial experiment within the randomized complete block design (RCBD) with two factors, the first was spraying the Gladiolus plant with boron element (B) in the form of BO3 and in four concentrations (B1 = 0 comparison treatment, B2 = 10, B3 = 20, B4 = 30 mg.l -1 As for the second factor, the plants were sprayed with brassinolide (BL) at three levels (Bl1 = 0, control treatment, Bl2 = 1, Bl3 = 2 mg.l -1 ) and the overlap between them, with three replications, and 4 plants in the experimental unit.The spraying process was done after emergence Three leaves on the plant, at the rate of three sprays, between one spray and another 10 days, and the results were analyzed by Genstat program, and the averages were compared with the value of L.S.D at a probability level of 5%.The study indicators included some of the characteristics of vegetative and flowering growth such as plant height, number of leaves, leaf area, chlorophyll content in leaves, shoot dry weight, flowering date, number of florets, duration of flowering on the plant, vase life of flowers, corm weight, corm diameter and number of corms.

Results and Discussion
The results of Table (1) indicate that spraying Gladiolus plants with boron and brassinolides, alone or in combination between them, led to an improvement in the vegetative growth characteristics.Chlorophyll and dry weight of shoots totaled (87.66 cm, 9.56 leaves, 124.49cm2, 43.17 mg.g -1 , 48.21 g) respectively, while the B1 measurement treatment recorded the lowest value for the same traits (72.01 cm, 6.75 leaves, 117.21 cm 2 , 2.85 mg.g -1 , 33.17 g), respectively.When the plant was sprayed with brassinolide, the results of the table showed that the Bl2 treatment was superior in the measured vegetative growth characteristics, represented by plant height, number of leaves, leaf area, leaf content of chlorophyll, and dry weight of the shoot total, as it reached (82.16 cm, 8.75 leaves, 122.04 cm 2 , 39.43 mg.g -1 , 43.59 g), respectively, while the measurement treatment Bl1 recorded the lowest value for the same characteristics, as it recorded (76.24 cm, 7.33 leaves, 119.29 cm 2 , 3.53 mg.g -1 , 33.50 g) respectively, but in the overlap coefficients, we notice the plant height characteristic The B4Bl3 treatment is superior to all other treatments and reached (90.57) cm, while the comparison treatment B1Bl1 recorded (69.60) cm.The same applies to the number of leaves, leaf area, leaf chlorophyll content and dry weight, as the B4Bl3 treatment recorded (10.67 leaves, 125.83 cm 2 , 54.33 cm 2 ) mg.g -1 , 58.17 g), while the comparison treatment recorded the lowest value for the same characteristics, as it recorded (6.33 leaves, 115.27 cm2, 2.53 mg.g -1 , 30.20 g), respectively.We also notice that in the characteristics of the number of corms, their diameter and weight, the boron spraying treatment B4 was superior to (6.00 corms, 4.58 cm, 131.0 g), respectively, while the measurement treatment B1 recorded the lowest value for the same characteristics (2.67 corms, 2.85 cm, 69.8 g), respectively.As for spraying with brassinolide and for the same characteristics, the Bl3 treatment was superior to the other treatments as it reached (4.83 corms, 4.10 cm, 109.0 g), respectively, while the control treatment, Bl1, recorded the lowest value (3.42 corms, 3.53 cm, and 85.6 g).While the results of Table (1) showed that the interaction between spraying plants with boron and brassinolide led to an increase in the number of corms, their diameter and weight, as treatment B4Bl3 excelled over other treatments and reached (7.33 corms, 4.80 cm, 152 g), respectively, while the comparison treatment recorded the lowest value, as (2.33 corms, 2.53 cm, and 60.7 g) were recorded, respectively.
Table 1.The effect of boron and brassinolide spraying on the vegetative growth characteristics of Gladiolus plants.In terms of flowering growth, the results of Table (2) showed the superiority of boron B4 spray treatment over other treatments in terms of early flowering, duration of flowering on the plant, number of flowers, and vase life, which amounted to (78.89 days, 13.67 days, 9.00 florets, and 12.78 days) respectively in When the measurement treatment B1 recorded the lowest value for the same traits, as it recorded (96.22 days, 8.22 days, 7.67 flowers, and 9.33 days), respectively, and when spraying plants with brassinolide, we notice the superiority of treatment Bl3 and for the same characteristics mentioned over other treatments, as it reached (83.75 days, 11.33 days, 8.67 flowering, 11.75 days), respectively, while the Bl1 control treatment recorded the lowest value and recorded (90.08 days, 9.75 days, 7.83 flowering, and 9.92 days), respectively.As for the interaction treatment between spraying with boron and brassinolide, the results of Table (2) show the superiority of B4Bl3 treatment IOP Publishing doi:10.1088/1755-1315/1259/1/0120604 compared to other treatments in terms of early flowering, the duration of flowers remaining on the plant, the number of flowers, and vase life, which amounted to (75.00 days, 14.67 days, 9.67 florets, and 14.67 days), respectively, while the measurement treatment B1Bl1 recorded the lowest value for the same traits mentioned, as it recorded (100.00 days , 7.67 days, 7.33 flowers, and 9.00 days vase life), respectively9 Table 2. Effect of spraying boron and brassinolide on the flowering growth characteristics of gladiolus plant.
We notice an improvement in the characteristics of vegetative and flowering growth when spraying plants with boron, and the reason may be due to the improvement in the growth and development of the treated plants, as boron helps in activating the metabolism processes in the plant, which are photosynthesis, enzyme activities, hormones synthesis and nitrogen fixation.The characteristics of vegetative growth and thus improving the characteristics of flowering growth [12][13][14] .but when spraying the plant with brassinolide, it improved the characteristics of vegetative growth because it stimulates the plant to increase the absorption of elements from the soil Increasing the nitrogen requirement in the plant as well as increasing the efficiency of photosynthesis, and this causes an increase in vegetative growth, and brassinolide affects the elongation and growth of cells and causes an increase in the level of internal hormones, which leads to stimulation of the formation of pigments, especially chlorophyll, in addition to the synthesis of ethylene, which leads to early flowering [15][16][17].

Conclusion
The characteristics of vegetative and blooming growth, as well as the quality of the corms, were enhanced after Gladiolus plants were sprayed with boron and brassinolide at the quantities stated.It is clear from the data that the enhancement of vegetative growth characteristics had a favorable impact on blooming growth characteristics and corm production.