Effect of Zinc as a Foliar Spray on Growth And Flower Production of Marigold ( Tagetes erecta L . )

An experiment was conducted to check the response of Marigold (Tagetes erecta L.) to foliar spray of zinc (Zn) on growth and flower production at the Ornamental Horticulture Nursery, Department of Horticulture, The University of Agriculture Peshawar in 2014. The experiment was laid out in a Completely Randomized Design (CRD) with one factor repeated thrice. In this study, Marigold plants were sprayed with five level of zinc sulphate (0, 0.3, 0.5, 0.7 and 0.9%). Result revealed that most of the traits were significantly affected by zinc while leaf area showed non-significant differences. Maximum plant height (25.84 cm), stem diameter (0.75 cm), number of flower plant-1 (14.66), fresh flower weight (4.67 g), number of branches plant-1 (23.22) and number of leaves branches-1 (40.36) were recorded at 0.5% Zinc sulphate application. Hence, it was concluded that 0.5% of zinc should be sprayed for good quality flower production of Marigold flowers; this is therefore the recommended dosage for the farmers of the agro-climatic condition of Peshawar.


INTRODUCTION
Marigold, a member of the family Asteraceae or Compositae, is a potential commercial flower that is gaining popularity on account of its easy culture, wide adaptability, and increasing demand in the subcontinent (Asif, 2008).Marigold is grown as an ornamental crop for its flowers, which are sold in the market as loose flowers in bulk, specialty cut flowers, or for making garlands.
Zinc (Zn) is an essential element for plants growth and acts as a metal component of various enzymes or as a functional structural or regulatory cofactor for protein synthesis, photosynthesis, synthesis of auxin, cell division, maintenance of membrane structure and function and sexual fertilization (Marchner, 1995).Zn is the second microelement after iron (Fe) and is involved in various biological processes in organisms (Broadley et al., 2007).Zn is an important essential micronutrient for plant.Zinc is an essential metal for normal plant growth and development since it is a constituent of many enzymes and protein in organisms.In rice production, yields are often reduced and Zn mass concentrations in the grains are often low when Zn is in short supply to the crop (Gao et al., 2006).Zn is the second most abundant transition metal after iron (Fe) and is involved in various biological processes in organisms (Broadley et al., 2007).Final production (quantity and quality) is one of the main characteristics that should be evaluated in studies concerning plant crops (Medina et al., 2007).
There are several investigations on the consequence of spraying macro and micronutrients for plant development, yield and fruit excellence (Gobara et al., 2001).Zinc increasing levels resulted in increasing plant height, number of fruits, fruit diameter and fruit yield.However, rising levels resulted in increase in the development, height and fruit yield (Naruk et al., 2000).According to Stout (1962) plants are considered as biological machines; their bodies are constructed from macro-elements and their working parts consist of proteins and enzymes revolving about nitrogen (N) atoms and the 'micronutrient' provide the special lubricants required for a variety of energy transfer mechanisms within the plants.
Foliar feeding that is functional to plant leaves and leaves are green factories where multipart chemical process of photosynthesis produces compounds that are required for plant growth.Foliar feeding of nutrients has become an established procedure to increase yield and improve the quality of crop products (Romemheld and El-Fouly, 1999).This procedure improves nutrient utilization and brings environmental pollution to the minimal by reducing the amount of fertilizers added to the soil.Foliar feeding of nutrients may actually promote root absorption of the same nutrient or other nutrients through improving root growth and increasing nutrients uptake (Saqib et al., 2006).This study presents the report on the main characteristics of flowering of marigold under application of zinc sulphate in foliar spray application.

MATERIALS AND METHODS
This experiment was conducted to find out the effect of foliar application of Zinc (Zn) on Marigold, at the Ornamental Horticulture Nursery, Department of Horticulture, The University of Agriculture Peshawar in the year 2014.

Planting materials
The experiment was conducted in a Completely Randomized Design (CRD) with one factor repeated thrice.The local variety of marigold (Tagetes erecta) was selected.The seedlings were taken from "Elite Nursery" Peshawar.Seeds were sown on 17 th August and germinated 25 th August, 2014.On 27 th August, 2014 seedlings were transplanted from 3 to 4 true leaves stages to wellprepared plastic bags.Bag size was 15 cm diameter containing farm soil.Zinc levels (0, 0.3, 0.5, 0.7 and 0.9%) were applied to plants through foliar spray.For each treatment, the five plants were kept in one plot and a total of twenty five numbers of plants in each replication.All the cultural practice such as (pest control, irrigation, hoeing and weeding etc) were kept constant.The following growth attributes were studied during the course of the experiment.

Plant height (cm)
From each treatment in each replication three plants were randomly selected and stems measured with measuring tape and the average calculated.

Stem diameter (cm)
Diameter of the stem of three randomly selected plants from all treatments in each replication was measured with the help of vernier caliper and the average calculated.

Number of branches plant -1
From each treatment in each replication three plants were randomly selected while branches were counted and the average calculated.

Number of leaves branch -1
The total numbers of leaves were counted in each treatment in each replication of the three plants randomly selected and the average calculated.

Leaf area (cm 2 )
From each treatment in each replication three plants were randomly selected and the leaf area determined with the help of leaf area machine and the average calculated.

Number of flowers plant -1
From each treatment in each replication three plants were randomly selected, flowers were counted and the average calculated.

Flower fresh weight (g)
From each treatment three plants were randomly selected and the fresh weight was determined by digital weight balance and the average calculated.

Statistical analysis
The data recorded on different parameter were analyzed using the statistical computer software, MSTATC (Michigan state university, USA).Analysis of variance (ANOVA) and LSD test were performed to find out the difference between treatments.The mean values for difference were compared using Least Significant Difference Test (Steel et al., 1997).

Plant height (cm)
The results of the analysis variance showed that the application of different treatments of Zinc sulfate has significant effects on the plant height (cm) of marigold plant (Table 1).By the comparison of means, maximum plant height (25.84 cm) was recorded at (0.5 %) zinc, while minimum plant height (17.73 cm) was observed in control treatment (0%) zinc.Foliar spray of Zn significantly increased plant height of Gerbera (Khosa et al., 2011) and increased the height of Iris plants (Khalifa et al., 2011).Similar results were observed by Rahmati et al. (2009) in pot marigold.Dadkhah et al. (2012) expressed that consumption of fertilizers stimulates plant growth and better establishment of plants and in addition leads to increase in morphological characters such as plant height of matricaria (Matricaria chamomilla).

Stem diameter (cm)
The statistical analysis of the data presented that different zinc level had a significant effect on stem diameter (cm) of marigold plant (Table 1).By the comparison of means, maximum stem diameter (0.75 cm) was recorded at (0.5 %) zinc, while minimum stem diameter (0.02 cm) was observed in control treatment (0%) zinc which was statistically similar with stem diameter (0.03 cm) at 0.3 and 0.7% respectively.This may be due to zinc being an essential constituent of cell component and constituents of the various cell membranes that are also important for the maintenance of cell structure and induced cell division which resulted in enhanced vegetative growth of stem diameter (Kendra et al., 2013).The improvements in these characters might be due to enhancement in vegetative growth which is likely to be responsible for more accumulation of photosynthetic materials, hence, resulted in giving maximum value in these characters.These findings are very similar to the findings of John and Paul (1999) and Belgaonkar et al. (1996) in chrysanthemum.

Number of branches plant -1
The statistical analysis of the data revealed that different Zinc level had significant effects on the number of branches plant -1 of marigold plant.As regarding foliar application of zinc, more number of branches plant -1 (23.22) was recorded at (0.5%), while lesser number of branches plant -1 (12.33) was observed in the control treatment (0 %). Pirzad et al. (2013) reported that spraying of zinc has significant effect on the number of branches of anise (Pimpinella anisum).

Number of leaves branch -1
The statistical analysis of the data revealed that Zinc level had a significant effect on number of leaves plant -1 of marigold plant.As regarding foliar application of zinc, more number of leaves branch -1 (40.36) was recorded at (0.5%), while lesser number of leaves branch -1 (30.66) was observed in the control treatment (0%).Foliar application of zinc sulphate (ZnSO4) significantly increased the number of leaves per plant in Iris (Khalifa et al., 2011).Similarly, Khosa et al. (2011) observed a significantly higher number of leaves per plant in Gerbera due to foliar application of Zn.In addition, El-Khayat (1999), mentioned that, spraying Antholyza aethiopica with Zn had a promoting effect on increasing the leaf number per plant.

Leaf area (cm 2 )
Data regarding leaf area (cm 2 ) showed that different levels of zinc had no significant effect on the leaf area (cm 2 ) of marigold plant (Table 2).However, comparing the means of leaf area, it is clear from the mean table that wider leaves (1.14 cm 2 ) were recorded at (0.5% zinc sulphate), while minimum leaf area (0.94 cm 2 ) was recorded in 0.03% Zinc application.

Number of flowers plant -1
The statistical analysis of the data revealed that different levels of Zinc had significant effects on number of flower plant -1 of marigold plant.Comparing the means of number of flowers plant -1, it is clear from the mean table that more number of flower plant -1 (14.66) was recorded at (0.5% zinc sulphate), while lesser number of flowers plant -1 (8) was observed in the control treatment (0%).Foliar application of nutrients is in resulted in more significance in fertilization of various field and floricultural crops in several countries.The advantages of foliar fertilizers were more noticeable under growing conditions restricting the incorporation of nutrients from the soil as reported by Verma (2003).Foliar fertilization method may also be a good substitute to the predictable soil application to avoid loss of fertilizers by leaching and thereby minimizing the ground water pollution (Tomimori et al., 1995).Zinc plays an important role in the production of biomass (Cakmak, 2008).It may be required for chlorophyll production, pollen function and fertilization (Kaya et al., 2005).It was also reported by many researchers that zinc had a significant effect on flower production in Gladiolus (Halder et al., 2007).

Fresh flower weight (gm)
The statistical analysis of the data revealed that application of different levels of zinc resulted in a significant effect on fresh flower weight of marigold plant.
Comparing the means of flower weight, it is evident from the mean table that maximum fresh flower weight (4.67 g) was recorded at (0.5% zinc sulphate) while minimum flower weight (2.12 g) was observed in the control treatment (0%), which was statistically similar with flower weight (2.67 g) at 0.3% respectively.Increase in fresh weight of flowers might be attributed to increased fresh weight of complete stem due to good growth of plants.These findings are in accordance with the results of Singh and Bhattacharjee (1997), who observed increase in fresh weight of rose flower as a result of foliar application of micronutrients.Khalifa et al. (2011) also noted that fresh weight increase in Iris flowers was due to either foliar application of ZnSO4 applied singly.

CONCLUSION AND RECOMMENDATION
From the aforementioned results, 0.5% foliar application of Zinc Sulphate was better for all of the parameters such as plant height, stem diameter, number of flowers plant -1 , fresh flower weight, branches plant -1 and number of leaves branch -1 , while number leaf area was not positively affected by zinc application.For better growth and quality of flowering zinc performed better and was recommended at the rate of 0.5% for marigold.

Table 1 .
Effect of zinc level on plant height (cm), stem diameter, number of branches plant -1 , number of leaves branch -1 of marigold plant.

Table 2 .
Effect of zinc level on leaf area (cm 2 ), number of flower plant -1 and fresh weight of marigold plant.