Effect of zinc and iron on growth, flowering and shelf life of marigold under the agro-climatic conditions of Sawabi

A field experiment on the “Effect of zinc and iron on growth, flowering and shelf life of marigold” was carried out at Agricultural Research Station Swabi during 2018,to determine the optimum level of zinc and Iron on growth, flowering and shelf life of marigold flower, for the purpose to fulfill the demand of cut and loose flowers in local market. The experiment was laid out in Randomized Complete Block Design (RCBD) having three replications. Two factors were used in the experiment i.e. Four levels of zinc (0, 0.2, 0.4 and 0.6 %). And three levels of iron (0, 0.3 and 0.6 %). Zinc sulphate and iron sulphate were used as source for zinc and iron application. The results of the experiment showed that the maximum number of branches plant (17.33), number of flowers plant (10.11), flower diameter (9.10 cm), fresh flower weight (17.51 g), dry flower weight (3.06 g), shelf life (5.22 days) and minimum days to flowering (16.67 days) was observed on 0.6 % application of zinc as a foliar spray. Maximum plant height (49.04 cm) and stem diameter (1.12 cm) was noted on 0.4% of zinc foliar application. In case of iron maximum number of branches plant (18.58), numbers of flowers plant (10.79), flower diameter (9.48 cm), fresh flower weight (19.36 g), dry flower weight (3.40 g), shelf life (5.67 days) and minimum days to flowering (15.42 days) was recorded on 0.6 % application of iron. Maximum plant height (51.22 cm) and stem diameter (1.19 cm) was observed on 0.3% of iron foliar application. From the results of the experiment it has been concluded that the application of zinc and iron at the rate of 0.6% gave maximum growth and better quality flowers of marigold in district Swabi and hence recommended for the agro climatic condition of Swabi.


Introduction
Marigold (Tagetes erecta L.) is a beautiful commercial flower of Asteraceae family. The genus of annual and perennial plants which belongs to sunflower family (Asteraceae or Compositeae) is Tagetes. Its genus was designated by Linnaeus in 1753. The genus of marigold is originated from South and North America. But some genus is adopted throughout the world. The market value and demand of marigold in the subcontinent is very high due to its high range of adaptation. In some areas of the world some species of marigold such as Tagetes minuta is known to be toxic and harmful [1]. The height of Tagetes family ranges from 0.1 to 2.2 m. The leaves of most species are green and pinnate. The natural colors of bloom marigold flowers are orange, yellow, golden, white and having maroon color highlights. The floral head diameter of marigold flower ranges from 4 to 6 cm, usually with both disc florets and ray florets. The most popular species of marigold which are grown such as Tagete spatula L. and Tagetes erecta L. are originated from South Africa and Mexico correspondingly. Tagetes erecta L.is generally famous as African marigold, while T. patula as French marigold. Although the origin of African marigold T. erecta is Mexico, it is presumed to be of Indian origin, due to its adaptability, popularity and wide cultivation in India. Marigold is generally popular because of its easy cultivation, the adaptability to varying soil and climatic conditions, long flowering duration, wide range of attractive colors and good keeping quality of flowers. Due to these reasons, marigold is used as cut flower and in garden displays, garlands, bouquets and stage decorations [2]. The African marigold (Tagetes erecta L.) produced flowers having orange or yellow color and having big size of flowers [3]. The demand of the cut flowers is very high because of the beautification and attraction of the flower [4]. Due to modern technology new colors have been presented in the cultivars of cut flower as a result of which the market value and demand of the marigold flowers improved [5].
There is a plenty possibility to improve the production of Marigold by implementing appropriate crop managing methods. In order to achieve good quality and maximum production of marigold flowers, we have to improve production and to reduce the physical and biological diseases, submission of main and micronutrients are unavoidable. Now-a-days, micronutrients particularly zinc and irons are slowly achievement impetus amongst the flower cultivators for the reason that, their useful nutritious maintenance and to confirm healthier yield and revenues. Best responses of African marigold for small quantities of micronutrients have been demonstrated by [6]. An appropriate micronutrient amount, period and technique of application will positively increase the productivity and flowers quality [7]. Zinc is an important micro nutrient for plant and plays a vital role in various processes in plants. Zinc is helpful for the production of proteins in plants and a major constituent of ribosomes and important for its development. Zinc is an active nutrient in various biological and chemical processes and has interaction with other elements due to which the uptake of other elements increased. The production of auxin also related with zinc which plays a vital role in plant growth [8]. Zinc is also involved in the production of carbohydrates, absorption of phosphorus and production of RNA. It has noted that zinc is an essential factor of various enzymes and is an important element for the growth and development of plant. Zinc is also known as an important constituent for many growth promoting substances such as for the synthesis of tryptophan and a precursor of indole acetic acid. It has been reported that the essential oil percentage, oil yield and flowers yield of chamomile was increased with the application of zinc [9]. Iron is also important micro nutrients which plays an important role in the respiration and photosynthesis and also affects its properties. Studies showed that iron is an important nutrient for the growth of plant tissues [10]. The shortage of iron can cause several physiological abnormalities such as chlorosis, scorching and resetting etc. [11].
Iron is also related with the establishment of chlorophyll. Iron has also a key character in the activation of several enzymes [12]. The studies showed that the application of iron and zinc play a role in the physiological growth the flowers and reduced the amount of ethylene and abscisic acid and as a result of which the shelf life and visual attraction of the flowers increased [13]. Keeping in view the importance of zinc and iron an experiment was conducted to determine the impact of zinc and iron on growth, flowering and shelf life of marigold flowers in the conditions of district Swabi having the objectives to determine the optimum level of zinc on growth, flowering and shelf life of marigold flower and to investigate the optimum level of Iron on growth, flowering and shelf life of marigold flower.

Materials and methods
An experiment "Effect of zinc and iron on growth, flowering and shelf life of marigold" was carried out at Agricultural Research Station Swabi, during 2018. The research was aimed to find out the growth, flowering and shelf life of marigold flowers. The research was arranged in Randomized Complete Block Design (RCBD). Total treatments were 12 and all treatments were replicated three times i.e., control, zinc, iron and their interaction ( Table 1).

Table 1. Distribution of factors, treatments and their levels Factor A (Iron)
Factor B (Zinc)

Preparation of field
Before sowing of plants, field was ploughed thoroughly and leveled. Field was cultivated with the help of mechanical Cultivator. Soil was fine graded and pulverized. All cultural practices i.e., irrigation, weeding and crop protection was adopted according to the need till the trial end.

Planting materials
Hybrid variety (Inca 2 yellow) Tagetes erecta was selected. Seedlings were taken from Agriculture research station swabi. Seedlings were transplanted to plot in the mid of September 2018, when reached to 4-5 leaves stage with 40 X 30 cm plant spacing. Zinc and iron was applied before emergence of flower buds. Zinc sulphate and iron sulphate was taken as source for foliar application of zinc and iron.

Study parameters
The subsequent parameters were recorded.

Plant height (cm)
Data on plant height were recorded with the help of measuring tape from the base of plant to top of plant. From each treatment plants were selected randomly in each replication and mean data was noted.

Number of branches plant 1
The data on numbers of branches were calculated by calculating the amount of branches of every treatment in all of the replication. For this purpose five plants were randomly selected in all treatment and in every replication and their number of branches plant -1 was counted and then their mean was calculated.

Stem diameter (cm)
Stem diameter data were taken through the use of Vernier caliper. In each treatment and every replication five plants were randomly selected and their stem diameter was calculated and then their mean was calculated for further statistical analysis.

Days to 1 st flowering
Days to 1 st flowering were recorded from plant sowing to emergence of 1 st flowering. And days were counted after emergence of more than 50 percent plants and then their average was calculated.

Flower diameter (cm)
Data of flower diameter were recorded with the help of Vernier caliper. Randomly five flowers were selected in each treatment and each replication and then their diameter was calculated. After that their average was noted for further analysis.

Flower fresh weight (g)
Data were taken by weighting fresh flower with the help of digital scale. Five randomly flowers were selected in every treatment and every replicates and their weight was noted and their mean was studied for further analysis.

Flower dry weight (g)
Randomly five plants were selected and then dried in oven. After that their weight was calculated by using electronic scale and then their average was noted.

Total number of flowers plant -1
Five plants were randomly selected in every treatment of the trial and then their flowers were counted. And then their average was calculated for further analysis.

Flower shelf life (Day)
For shelf life of marigold five flowers were selected and was kept at room temperature, their shelf life data were noted and then their average was calculated for further statistical analysis.

Statistical procedure
The data noted from the experiment was analyzed through analysis of variance method. Significant data were further analyzed through simple least significant differences (LSD) test. For all this calculation statistical software "Statistix 8.1" was used [14].

Results and discussion
The results obtained of different parameters are discussed as below Plant height (cm) Mean

Number of flowers plant -1
Mean table (6) revealed that the foliar application of zinc and iron significantly affected the numbers of flowers plant -1 , whereas the interaction of these treatments was found-non-significant. The maximum numbers of flowers plant -1 (10.11) of marigold was observed in those plots which were treated with 0.6 % application of zinc which was followed by 0.4 % application of zinc (9.67), whereas the minimum numbers of flowers plant -1 (8.56) was observed in control. In case of iron application as a foliar spray, the maximum numbers of flowers plant -1 (10.79) was observed in plots which were treated with 0.6 % foliar application of iron, while the minimum flowers plant -1 (7.79) was recorded in control plots.
The increased in number of flowers plant -1 maybe due to the useful and essential character of zinc in improving the translocation of carbohydrates, water, amino acid and mineral from source to sink particularly on flower as a result of which the number of flowers increased [7]. The similar result was also noted by [6] in African marigold at 0.75 % zinc sulphate. There is a direct effect of iron on the synthesis of chlorophyll as a result of which the photosynthesis rate increased and produced more food, due to which the flower numbers plant -1 was increased [13]. Our finding are same with the finding of [23] who concluded that the application of iron the number of flowers plant -1 increased in French marigold.

Flower diameter (cm)
Mean table (7) shows that the flower diameter of marigold was significantly affected by the foliar application of zinc, iron and their interaction. The maximum flower diameter (9.10 cm) of marigold was observed on 0.6 % application of zinc. However the minimum flower diameter (8.28 cm) was recorded on control. The maximum flower diameter (9.48 cm) of marigold was recorded on 0.6 % of foliar application of iron, whereas the minimum flower diameter (7.74 cm) was noted in control plot.In case of interaction the maximum flower diameter (9.80 cm) was recorded on 0.6 % zinc application and 0.6 % application of iron, while the minimum flower diameter (07.0 cm) was recorded on control. Studies showed that zinc is an important micro nutrient for plant growth and development [9]. Several enzymes are activated with the application of zinc such as tryptophan, dehydrogenase etc. Zinc is also an important factor of the formation of chlorophyll and several other physiological due to which the flower diameter increased [35]. [36] Concluded that zinc application at the rate of 0.4 % gave maximum flower diameter of lilium. Iron is related with the formation of chlorophyll. Iron also act as a catalyst in many reactions. It is also important for photosynthesis and respiration

Fresh weight of flower (g)
Mean table (8)shows that fresh flower weight of marigold was significantly affected by foliar application of zinc and iron, the interaction of the treatment was found nonsignificant. The maximum fresh weight of flower (17.51 g) was observed in those plots which were treated with 0.6% application of zinc as a foliar spray followed by 0.4 % zinc application (16.

Dry weight of flower (g)
Mean table (9) shows that the dry weight of flower was significantly affected by the foliar application of zinc, iron and their interaction. The maximum dry weight of flowers (3.06 g) of marigold was noted in those plots which were treated with 0.6 % foliar application of zinc. The minimum dry weight of flower (2.49 g) was recorded on control. In case of iron application, the maximum dry weight of flower (3.40 g) was recorded on 0.6 % application of iron, whereas the minimum dry weight of flower (2.02 g) was observed in control plots. In terms of interaction between the zinc and iron, the maximum dry weight of flower (3.55 g) was recorded on 0.6 % zinc and 0.6 % iron, while the minimum dry weight of flowers (1.53 g) was observed in control. A significant variation was observed on dry flower weight of marigold with the foliar application of zinc. It has been reported that the foliar application of zinc relived chlorosis in the leaves of the plant and produced green and healthy plants. Zinc is also a significant constituent of chlorophyll by which the photosynthesis of the plant increases which resulting maximum flower weight [41]. The same result was noted by [42] who reported that the dry weight of chrysanthemum was increased with zinc application. They noted that the 0.6 % zinc sulphate produce maximum dry weight of flowers. Iron act as a catalyst in several chemical reactions and plays a role in the synthesis of chlorophyll and other physiological activities due to which flower weight and yield may be enhanced [12]. The similar result was noted by [43] who reported that the dry mass of African marigold improved with the application of iron and zinc at the rate of 0.5 % and 0.75 % respectively. Our result is similar to the conclusion of [46] who reported that the shelf life of tuberose improved with the application of zinc. Iron also increased the storage of carbohydrates through the increased in the rate of photosynthesis