The Application of Different Levels of Ammonium Nitrate in the Form of Fertilization on some Morpho-Physiological Traits of Spider plant (Chlorophytum comosum)

 The genus Chlorophytum (also known as spider plant) which is mainly cultivated as an ornamental plant for its slash and colored leaves, specifically distributed in the pantropic regions. It is a perennial rhizomatous plant with often short and indistinct rhizomes, while with thicker or slightly fleshy roots. The roots of these species are considered as one of the important phytochemical components. the use of Chlorophytum comosum as a contaminant accumulator has already been documented in the literature.This plant is a soil conditioner and can absorb lead, cadmium, Se and As while its leaves accumulate mercury. It is also able to absorb toxic organic pollutants such as formaldehyde and benzene and is also able to retain CO2. Leaf surface morphology has been shown to affect the ability of a particular plant to retain contaminants. Chlorophytum comosum introduced as a plant that requires high nitrogen. Nitrogen is an essential macro element for the growth and development of plants which involved in many physiological reactions and it is one of the elements that plants need in all their activities. The effect of N form on plant growth depends on plant species and nitrogen level of the soil. Plants absorb both ammonium (NH4+) and nitrate (NO3-) from soil solution, and these two mineral forms are their most important sources of nitrogen to supply the plant demand. Absorption of ammonium by plants requires less energy than absorption of nitrate. It seems that most plants have the best performance in a certain ratio of nitrate to ammonium (NO3-/NH4+ ratio). This ratio seems to regulate the distribution of absorbed nitrogen between the branches and roots. It may also vary between species. The optimal ratio may also depend on the environmental conditions such as pH, light intensity, and root zone temperature. This study was performed to determine the effect of different levels of ammonium nitrate on growth, yield factors and ornamental aspects of the spider plant as a desired ornamental product. The use of ammonium nitrate to meet the houseplants demand considering the supply of both types of nitrogen sources, increases the yield and quality of these plant. However, despite the importance of the nitrogen in the performance of this ornamental plant (Chlorophytum comosum), the desired amount of nitrogen for its growth and quality has not yet been reported. Therefore, the present study was conducted to investigate the effect of different levels of ammonium nitrate on the growth and physiological characteristics of spider plant to find the best level of application of ammonium nitrate fertilizer as an easily available source to increase the growth and visual quality of this plant.

 This research was conducted based on randomized complete block design (RCBD) with four treatments and three replications.  Treatments include four levels of ammonium nitrate of 100 (control), 200, 400, 600 mg-1 kg of soil. Treatments applied first at the substrate preparation process and then was applied in the one third depth of each pot, monthly. Desired factors such as morphological characteristics (plant height, leaf number, stolon number, fresh weight, dry weight, root fresh weight, root dry weight, root volume, root depth, root length, pot weight, leaf area) and physiological characteristics (total chlorophyll, total protein, texture nitrate and proline) were evaluated. Also soil analysis was performed before starting of the experiment. Statistical analyses of the data for examined traits were performed using SAS software and comparisons of means using Duncan's multiple range test, at 5% probability level.

 The results indicated that the application of ammonium nitrate fertilizer significantly improved most of the studied traits. Supplying ammonium nitrate fertilizer at desired level meet the nitrogen demand of Spider plant during the growth and improved production of biomass. The plant height, leaf number, fresh weight, dry weight, root fresh weight, root dry weight, and leaf area were increased by increasing ammonium nitrate level. Nitrogen fertilizers play an important role for increasing plant yield by expanding shoots and producing sufficient carbohydrates. In addition to plant growth, they also affect plant morphology. Maximum amount of protein, nitrate of tissue and total chlorophyll observed in 400 mg-1kg of ammonium nitrate level. Nitrogen is one of the essential elements that plays an important role in the production of chlorophyll and protein, therefore the use of nitrogen fertilizers leads to synthesis of chlorophyll and protein at higher level. The highest amount of proline (11.20 μg-1 mL) was measured at 600 mg-1kg of ammonium nitrate level and the lowest (3.57 μg-1 mL) in the control, because with high consumption of nitrate, the plant needs more water and nitrogen is a structural component of proline. Accumulation of proline helps the plant to survive and recover after drought stress.

 According to the results of our experiment, application of nitrogen fertilizer had a positive effect on growth, and consequently led to increase the plant vegetative yield. Treatment of 400 mg-1kg of ammonium nitrate level increased growth and yield factors and the ornamental aspect of Spider plant as a desired ornamental crop. Application of 400 mg-1kg of ammonium nitrate level are recommended to access an acceptable quantitative and qualitative yield in this plant.