عنوان مقاله [English]
Introduction: Tulip flower (Tulipa L.) from the family Liliaceae is a bulbous and monocotyledon plant that has the highest level under cultivation among this family group. Tulips can be propagated by seeds and bulbs. Its seeds produce bulbs up to two years after planting and it takes six years for the bulbs to reach the flowering stage. In fields, the quality characteristics of flowers can be changed to some extent by changing some planting characteristics such as planting pattern and plant density. Some researchers have reported changes in the quantitative and qualitative characteristics of various crops and orchards, including ornamental plants, with changes in planting pattern and plant density. One of the effects of changes in planting pattern and plant density is changes in photosynthesis and plant growth regulators. The purpose of this study was to introduce the best planting pattern, determination of the best planting density, and study the effect of plant pattern and planting density on the quantitative and qualitative characteristics of tulip (Tulipa L.) cv. ʹSpryngʹ.
Materials and Methods: To evaluate the effect of planting pattern and density on growth and flower characteristics of tulip cv. ʹSpryingʹ, a study was conducted as a factorial experiment based on completely randomized block design (RCBD) with 3 replications in 27 plots. The first factor was three planting patterns (square, triangle and rectangle) and three planting densities (25, 45 and 65 plant/m2) as the second factor. Morphological and physiological traits such as height, length and diameter of stem, leaf and flower, flowering time, cut flower number, flower longevity, number, diameter and weight of bulb and bulblet, and the content of chlorophyll and carotenoid were measured. Statistical analysis of data was performed with SAS 9 software and mean comparison of the data with LSD test at 5% probability level. Graphs were drawn in Excel.
Results and Discussion: Results showed that the maximum number of cut flowers (59.90) was counted in plants cultivated in triangle cultivation design with planting density of 65 plants/m2. The lowest time to start of flowering (69.30 days) and the highest content of leaf chlorophyll (13.57 μg/ml) was obtained in plants cultivated in trianle cultivation design with planting density of 45 plants/m2. The most flower longevity (12.73 day) and the highest content of carotenoid (1.68 μg/ml) was obtained in plants cultivated in square cultivation design with planting density of 45 plants/m2. The height of the flowering stem is one of the important traits for the marketing of cut flowers. The results of the present study showed that the height of the tulip plant was affected by plant density and planting pattern. This result was consistent with the results reported by some researchers. At low plant densities, long plant spacing reduces plant competition for water and nutrient uptake, resulting in larger plant growth and leaf size. Also, long plant distances cause the roots to develop and grow, and the leaves to grow and thicken. Increasing the vegetative competition of adjacent plants at high densities causes photosynthetic organs to be placed in the shade (change in the quantity and composition of the received radiation spectrum in the shade leaves), which has a great effect on the balance of plant growth regulators, resulted in longitudinal and superficial growth of plant organs. It intensifies the longitudinal growth of the petiole and accelerates all the developmental processes of the plant. Plant morphology and angle of leaf deviation can also be effective in increasing leaf size. Uniform distribution of plants and greater absorption of light and nutrients increased leaf length and width. The results revealed that plants compete for light and nutrients, and in these competitive conditions, roots and stems are taller than optimal, and the distance between nodes increases. The effect of planting pattern on flowering process can be related to changes in plant photosynthesis and the availability of photosynthetic materials for the developing reproductive parts. Changes in the planting distance or pattern change inflorescence characteristics by affecting root growth and altering the production of plant growth regulators in roots. Inflorescence characteristics are changed through the transfer of these plant growth regulators to the aerial parts. Changing the distance or planting pattern can affect some characteristics of bulb and bulblet of bulbous plants. Competition for receiving maximum light and photosynthesis is a key factor in changing bulb and bulblet traits. This competition is influenced by planting arrangement and plant density. Some studies have shown that planting pattern and plant density affect the amount of plant pigments such as chlorophyll and carotenoids, the main reason being the difference in light intake.