عنوان مقاله [English]
One of the forage crops which has recently taken into consideration is Amaranth (Amaranthus spp. L.) from Amaranthaceace, which could be placed in crop rotation because of both feeding characters and good adaptability. Fodder quality in this crop is strongly depended on the growth stage. The highest protein content (230 kg.ha-1) occurs in the flowering stage. After this stage, fodder quality will reduce (130 kg.ha-1) and the quantity of both ADF and NDF increase in stems, vice versa. Aynehband (2004) tested five Amaranth fodder cultivars and reported that dry matter of these cultivars were between 15 to 32 t.ha-1and concluded that the crop has a good potential in Khozestan farming system. The main goal of this research is to study the effect of organic and chemical fertilizer managements on yield and yield components of Amaranth.
Material and Methods
This field study was conducted in the summer of 2014 in research station of Agriculture Faculty, Shahid Chamran University of Ahwaz. The experimental design was split plot based on randomized complete blocks design with 3 replications. Main plot factors was five fertilizer managements including: 1- only chemical, 2- organic-A (Compost + Nitroplas + Barvar-2 as seed treatment+ Humicin as foliar application), 3- Organic-B (Vermicompost + Nitroplas + Barvar-2 as seed treatment + Phosphonitrocaras as foliar application), 4- integrated fertilize and 5- control (no fertilizer). Sub-plot factors was two Amaranth cultivar named Plansman and Koniz witch prepared from Zagreb university of Croatia. The seeds, with density of 12 plants in m2, was planted in 31 May and harvested in early flowering stage (23 August). Destructive sampling of both leaf and stem dry matter applied every 14 days. Statistical significance of all samples was determined by analysis of variance (ANOVA) and difference of means were compared by Duncan multiple- ranged test using SAS statistical software.
Results and Discussion
A: Seedling establishment stage
The highest dry matter at 30 days after planting in both Plansman and Koniz cultivars was belonged to Organic-B (43.55 g.m-2) and organic-A (38.83 g.m-2), respectability. Both organic-A and Organic-B fertilizer managements produced 3 times more total dry matter than control. This situation could be caused by improving root distribution in response to exudation of some stimulate chemicals produced by organic or biological fertilizers. In chemical management, LAI increased until 20 days after planting and then stopped for both cultivars. While, in organic and biological management, LAI continuously increased even after that. One main reason for this difference could be due to the fact that chemical fertilizer release nutrients all at once, but both organic and biological fertilizers are among slow-release fertilizers.
B: Crop yield
The highest and lowest plant height was belonged to Organic-B (109.6 cm) and control (65.3 cm), respectively. Also the highest (21) and lowest (16) leaf per plant belonged to Koniz and Plasman cultivars, respectively. Stem diameter was significantly different between fertilizer treatments. The highest and lowest stem diameter (1.59 and 1.08) was belonged to Organic-B and control managements, respectively. Superiority of Organic-B in stem diameter rather than other treatments was mainly due to higher stem dry mater (192.9 g.m-2) in this treatment. Highest fodder yield (192.93 g/m2) belonged to Organic-B treatment but had no significant difference with integrated method (181.23 g.m-2). It seems that more stem diameter and height were the main reason for higher stem weight in Organic-B treatment. Among Amaranth cultivars, highest (175.5 g.m-2) and lowest (136.7 g.m-2) stem weight was belonged to Koniz and Plansman cultivars, respectively. In addition, Koniz cultivar produced more yield than Plansman (321.11 vs. 24541 g.m-2). Leaf and stem dry matter are the most effective indices for determination of fodder yield and our results also showed that Organic-B treatment had a higher amount of these indices (159.2 and 192.9 g.m-2, respectively).
According to the results of this experiment, it has been concluded that Koniz cultivar had significantly higher fodder yield (321.6 g.m-2), stem dry matter (175.5 g.m-2), leaf dry matter (146.1 g.m-2), stem diameter (1.52 cm) and leaf number (21 leaf per plant) than Plansman cultivar. Therefore, the highest fodder yield (368.14 g.m-2) was belonged to Koniz cultivar in Organic-B fertilizer management. Generealy, our results showed the suitability of organic fertilizer management for Amaranth production in Khozestan climate, especially for Koniz cultivar.