Evaluation of Morphological Characteristics, Quantitative and Qualitative Yield of Echium amoenum as Affected by Plant Density and Application of Chemical (Urea) Fertilizer and Different Organic Fertilizers

Maintenance of soil fertility as a permanent bed for continuous production of agricultural products is one of the most important issues affecting the sustainability of food production. In order to achieve healthy food production, application of ecological inputs such as organic fertilizers are inevitable. Organic fertilizers are fertilizer compounds that contain one or more kinds of organic matter. They can improve the soil’s ability to hold water and nutrients. They create a beneficial environment for earthworms and microbial organisms that break the soil down into rich, fine humus. Compost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Compost can greatly enhance the physical structure of soil. The addition of compost may provide greater drought resistance and more efficient water utilization. Vermicompost is the final product of composting organic material using different types of worms, such as red wigglers or earthworms, to create a homogenized blend of decomposed vegetable and food waste, bedding materials and manure. Vermicompost helps store nutrients and keeps them safe from leeching and irrigation, functioning to balance hormones within plant physiology, and adding beneficial biology to soil. Vermicompost improves soil aeration, enriches soil with micro-organisms (adding enzymes such as phosphatase and cellulose), attracts deep-burrowing earthworms already present in the soil and improves water holding capacity, enhances germination, plant growth and crop yield, improves root growth and structure. Cow manure is an excellent fertilizer containing nitrogen, phosphorus, potassium and other nutrients. It also adds organic matter to the soil which may improve soil structure, aeration, soil moisture-holding capacity, and water infiltration. Plant density is the number of individuals of a given plants that occurs within a given sample unit or study area. Planting density can impact the overall health of plants. Plantings that are too sparse (the density is too low) may be more susceptible to weeds, while planting that are too dense might force plants to compete over scarce nutrients and water and cause stunted growth. Despite of many researches on the effect of organic fertilizers and plant density on different crops, information on the effects of these factors for many medicinal plants is scarce, therefore, in this study effect of organic fertilizers and plant density on morphological characteristics and yield of Echium amoenum in a low input cropping system was studied.

In order to evaluate the effect of different fertilizers on quantitative characteristics of Echium amoenum at different plant densities, a factorial experiment based on RCBD design with three replications was conducted in 2011-2013 growing seasons, in Ferdowsi University of Mashhad, Iran. Experimental factors included three plant densities (10, 5 and 3 plant per m2) and five different types of organic and chemical fertilizers (municipal waste compost, vermicompost, cow manure, chemical (urea) fertilizer and control).

The results showed that with reduction of plant density, effect of organic fertilizers on increasing the flower yield was exacerbated and at the lowest density, municipal waste compost, vermicompost and cow manures increased flower yield 112, 79 and 223% compared to control, respectively. In all studied densities, length of lateral branches in conditions of organic fertilizers application was more than control. Municipal waste compost, vermicompost, cow manure and chemical fertilizer increased total phenol 106, 54, 66 and 173% compared to control, respectively. In plant mean density (5 plant per m2), application of municipal waste compost, vermicompost and cow manure increased total anthocyanin 83, 74 and 57% compared to control, respectively. In general, result of this study showed that application of organic and chemical fertilizers at optimal plant densities, can improve growth characteristics and quantitative and qualitative yield of Echium amoenum.Organic fertilizers are the most significant resources for development of agricultural soil quality and increase in the yield of different medicinal plants. It has been reported that this ecological inputs provide favorable conditions for plant growth and development through improvement of physical, chemical and biological properties of the soil, therefore, it can be concluded that improvement of the most studied traits in the present study were due to use of organic fertilizers. Fallahi et al., (20) have reported the positive effects of organic fertilizers on the improvement of quantitative and qualitative characteristics in chamomile (Matricaria chamomilla L.). It seems that plants compete with each other over scarce nutrients and water in high plant density and cause stunted growth. Some other studies have reported that suitable plant density can increase the growth and yield of some medicinal plants such as coriander (Coriandrum sativum L.), Ajwain (Carum copticum L.), lemon balm (Melissa officinalis L.) and anise (Pimpinella anisum L.).

In general, results of this study showed that application of organic and chemical fertilizers at optimal plant densities, while improving growth and yield characteristics of Echium amoenum flower can be ensured health of production of this important medicinal plant.