عنوان مقاله [English]
Medicinal plants are valuable resources that they can play an important role in the health of the community, employment, increasing non-oil exports and preventing the genetic erosion of valuable species. The increasing tendency towards herbal medicine in the treatment of diseases, whether globally or internally, makes it unavoidable the necessity of medicinal plants cultivation in agroecosystems. Isabgol (Plantago ovata Forssk.) is an annual herbal medicinal plant from Plantaginaceae family, which about 25℅ of its seed weight is mucilage. It has originated from arid and semi-arid areas and is used widely in traditional and industrial pharmacology. The seeds of isabgol contain fatty oil, carbohydrates, proteins, mineral element and particularly mucilage which has many medical applications. Low water requirement and short growth period, makes this plant suitable for planting in semi-arid areas such as Khorasan. However, to the best of our knowledge, so far, the adaptability, growth, and yield of this plant have not been fully investigated in this area. Accordingly, the aim of this study was to investigate the effect of plant density and single or combined application of cow manure (CM) and chemical fertilizers (CF) on yield and yield components of the isabgol.
Materials and Methods
This experiment was arranged as a factorial layout based on a randomized complete block design with three replications at Sarayan Faculty of Agriculture, University of Birjand, Iran during 2017. Fertilization treatments consisted of single (40 t.ha-1 CM and 40 kg.ha-1 CF from the source of NPK) and combined (40 t.ha-1 CM + 20 kg.ha-1 CF and 20 t.ha-1 CM + 40 kg.ha-1 CF) application of organic and chemical fertilizers along with a control (no-fertilizer) which were evaluated at three levels of density (20, 40 and 60 plants. m-2). The measured traits included number of spikes per plant, spike weight, spike length, number of seeds per spike, 1000-seed weight, biological yield, seed yield, harvest index, mucilage percentage, mucilage yield, and seed swelling factor. Data analysis was done using SAS 9.2 and means were compared using FLSD test at a 5% level of probability.
Results and Discussion
Among all studied traits, the only simple effect of fertilizer application on seed and mucilage yields and the simple effect of plant density on seed yield was significant. Seed yield increased when plant density was enhanced, so that, this index was 459, 504 and 673 kg.ha-1 for planting densities of 20, 40 and 60 plants.m-2, respectively. Fertilizers' application in all levels of density decreased the seed yield. The highest seed yield belonged to non-fertilizer application and 60 plants.m-2 with 806.6 kg.ha-1, and the lowest amount of this index was obtained in 40 t CM + 20 kg CF at density of 40 plant m2 with 272.2 kg.ha-1. In terms of mucilage yield, except the treatment of 20 t CM + 40 kg CF which increased this index by 14%, other fertilizer treatments had no-significant different with control. Considering that the most traits related to yield and yield components of isabgol did not affect significantly fertilizer resources, it can be stated that these plants are suitable for low-input production systems. Therefore, it seems that the application of fertilizer resources in crops that are located prior to isabgol in rotation and availability of remaining nutrients can provide the nutritional requirements of this plant.
However, our findings of the response of isabgol to fertilizer application were different from the results of many previous studies on it, which reported that the use of cow manure in isabgol production, not only does not reduce seed and mucilage yield but also improved them. Probably, the amounts of fertilizers used in the current study have been higher in the plant requirements. Therefore, doing complementary studies with lower levels of fertilizers can be recommended.