عنوان مقاله [English]
Food production to meet the demand for the world's growing population will be more difficult in the second half of the century than the first half. The increase in world population will result to greater pressure on agricultural lands in order to produce more crops. Therefore, the idea of increasing production per unit of area is inevitable by the applying chemical fertilizers which consecutively leads to serious environmental consequences. The same is true for production of cosmetics and pharmaceutical species including Aloe vera gel which is attracting excessive interest during the recent years. Scientific investigations of A. vera show that when it is prepared as a gel, it is more effective in treating stomach ailments, gastrointestinal problems, skin diseases, constipation and radiation injury. In most of the experiments conducted on Aloe vera, only the morphological characteristics were considered and the physiological aspects as well as the growth indices have been overlooked. On the other hands there is a limited number of published scientific resources regarding the application of manure and biological fertilizers on Aloe vera. The aim of this study was to evaluate different nutritional management methods in production of Aloe vera as a medicinal plant under the climatic conditions of Bushehr province so as to replace the chemical fertilizers by the manure and biological ones. Introducing such ecological methods could take a step forward towards the sustainable production of this valuable medicinal species.
Materials and Methods
The experiment was arranged as split plots based on randomized complete block design with three replications on a land area of 500 m2. The main plot factor included the application of manure (0 and 20 tons per ha) and the sub plot factor was the application of biological and chemical fertilizers in five levels: 1- Chemical fertilizer (80 kg triple superphosphate per ha and 200 kg urea per ha), 2- biological fertilizer Mycorrhiza, 3- bio-fertilizer Nitragin which contained three genus of Azotobacterspp., Pseudomonas spp. and Azospirillum spp. 4- the combination of two biological fertilizers (Mycorrhiza+Nitragin), and 5- the unfertilized control. Leaf area index (LAI) and total dry matter (TDM) were measured 150 days after planting in monthly intervals. The measured values of LAI and TDM were subjected to functional growth analysis and growth indices including crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR) and leaf area ratio (LAR) were calculated.
Result and Discussion
The results showed that the interaction between manure and either of chemical or biological fertilizers on leaf area index and maximum dry matter production of Aloe vera was significant. Application of manure improved nearly all growth indices in comparison with plants did not receive manure. Manure combined with chemical fertilizer had the greatest impact on the growth of Aloe vera. So that integration of manure with chemical fertilizer was led to the highest values of LAI (6.1), CGR (0.79 g m-2 d-1) and TDM (111.57 g m-2). Finally, the results showed that chemical fertilizers can be replaced with combination of manure and biological fertilizers for higher and more quality of Aloe vera yield.
The results achieved in this study showed that Aloe vera had responded positively to different methods of nutrient management. Chemical fertilizer had a greater impact on the growth indices of Aloe vera than other fertilizers, furthermore when it used in combination with manure, growth was more pronounced in comparison with individual application. Although biological fertilizers used in this experiment were less effective than chemical fertilizer, all of them were improved Aloe vera properties compared to the control. Likewise, this improving properties was different in combination of biological treatments with or without manure. When manure was used, combination of biological treatments wiht manure was better than their separate application. When manure was not used, separate application was better than their integrated.
We are grateful to Ebrahim Farrokhi and Kohzad Sartavi for their help with the field experiments, collecting field data and providing necessary advices to carry out this work.