The Effects of Manure and Biological and Chemical Fertilizers on Yield and some Morphological Characteristics of Aloe vera (Aloe burbadensis Miller.) in Bushehr Province

Aloe vera is a permanent, evergreen species with special industrial and pharmaceutical applications. However, information about its nutrition management is scarce. Plants absorb nutrients through complex interactions in the rhizosphere between roots, symbiotic or non-symbiotic microorganisms and soil fauna. Inoculations of soil microorganisms (in the form of biofertilizers) to improve crop production and plant health were mainly undertaken for the group of bacteria known as PGPB (plant growth-promoting bacteria) or PGPR (plant growth-promoting rhizobacteria) and mycorrhizal fungi. To be effective, inoculated organisms must have soil conditions that are suitable for development, which can be improved by applying manure. Compared to the use of inorganic fertilizers, the application of organic manure in agriculture fields results in significant effects on microbial biomass, on the profile of existing species and, consequently, on the enzymes they circulate in the soil and its pool of organic matter. In this way, it interacts with the overall fertility of the environment. Different options of soil fertility management for increasing yield of aloe vera were studied in a field experiment.

A split plot experimentwas conducted based on randomized complete block design with three replications during 2012-2013 growing season in Agricultural Research Center of Bushehr province (29º16'0"N 51º31'0"E and 110 m above sea level). Seedlings were planted on May 4, 2012 with a distance of 0.7 m spacing on row with 1 m distance. The distance between Aloe vera rows was 1 m. The drip irrigation method was used for irrigation.  Main plot factor consisted of 0 and 20 ton.ha-1 sheep manure and five methods of soil fertility management were assigned to subplots including 1) chemical fertilizer (80 kg.ha-1 super phosphate+200 kg.ha-1 urea), 2) Mycorrhiza (using soil containing fungi from mosea), 3) biological fertilizer nitrogen (containing Azotobacter spp; Pseudomomas spp; and Azosprillium spp), 4) combination of Mycorrhiza and Nitrogen, and 5) no fertilizer (control). Monthly samplings were taken in 150, 180, 210, 240, 270 and 330 days after planting. Fresh and dry weight of leaves, leaf length, width and thickness and number of leaves per plant were measured. Harvestable leaves were considered as final yield.

The results indicated that interaction between manure and chemical or biological fertilizers was significant for all measured traits. Application of sheep manure was led to significantly higher growth and yield of aloe vera with better performance when manure was combined with chemical fertilizers. The highest number of leaves was obtained from integrated use of manure and chemical fertilizers with about 15 leaf per plant. While the lowest number of leaves was observed in control treatment. The interaction between treatments had a significant effect (p≤0.01) on leaf thickness. Plants treated with combination of chemical fertilizer and sheep manure had significant differences with other treatments, except with integrated use of biological fertilizers and manure. The highest fresh and dry weight of plant 3107.2 and 78.1 g plant-1, respectively and the highest final yield (36.04 tons.ha-1) was achieved with integrated use of manure and chemical fertilizers. The results also indicated that high aloe vera yields with great quality could be obtained with combined application of manure and biological fertilizers as an alternative for chemical fertilizers.

Producing medicinal plants under low input of chemical fertilizers is of great importance for human health, environment as well as production costs. Results of this experiment showed that application of manure with biofertilizers could be considered as a proper alternative to chemical fertilizers. Nutrition of aloe vera with this integrated management method will results to high yield and quality in addition to improving the physical, chemical and biological properties of soil.AcknowledgmentWe 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.