Studying the effect of phosphorus on flowering and vegetative traits of zinnia (Zinnia sp.) in vermicompost medium

Abstract

Zinnia flowers have long flowering period and used as ornamental pot plants and cut flowers and also outdoor in landscape. In a greenhouse, the effects of phosphorus spray, and adding vermicompost to the medium on the characteristics of vegetative and flowering traits in zinnia were studied. Treatments consisted of phosphorus at three levels (0, 0.5 and 1 mg kg) and vermicompost at three levels (0, 10 and 20% vol). The experiment was factorial based on a completely randomized design with three replications. Plants grown in greenhouse conditions for two months. The plants were then cut off from the crown and the leaves and stems were separated. Some of the traits measured included dry weight of the plant, chlorophyll content, vegetation index, root length, flowering stalk, and flower diameter. The results showed that the use of phosphorus and vermicompost at higher percentages had a significant effect on the measured traits compared to control. The highest diameter of flower was 5.5 cm and the maximum length of flowering stem was 32.5 cm in treatment of 1 mg kg phosphorus and 20% vermicompost. Furthermore, chlorophyll a and b (SPad), fresh and dry weights, and vegetation index were observed at levels of vermicompost of 20% and phosphorus of 0.5 and 1 mg kg. The results showed that adding vermicompost to the medium with foliar application of phosphorus improves vegetative and reproductive traits of zinnia flowers.