Response of sunflower to organic and chemical fertilizers in different drought stress conditions

The main objectives of this research were to determine the effects of applying organic and chemical fertilizers under different irrigation regimes on sunflower (Helianthus annuus L.) morphological traits, yield components, grain yield and grain quality. The experiment was conducted as spilt plots based on a randomized complete block design with three replicates. Irrigation treatments at three levels (well-irrigated, mild and severe drought stress) were allocated to main plots and eight fertilizer treatments (urea (F1), urea + composted cattle manure (F2), zeocompost (F3), vermicompost (F4), zeolite-amended chicken manure (Z-ACM) (F5), zeocompost + vermicompost (F6), zeocompost + Z-ACM (F7) and vermicompost + Z-ACM (F8)) were randomized in sub-plots. The results showed that irrespective of the drought stress intensity, organic fertilizer treatments produced more dry matter, heavier and greater grain than did chemical treatments. In well-irrigated plots, the highest grain yield was obtained from F6, F7 and F8 treatments. Under drought stress conditions, the highest grain yield was obtained from the high zeolite content organic fertilizers i.e. F3, F5 and F7. We concluded that amending soil with organic fertilizers in combination with zeolite can be a beneficial approach for decreasing chemical fertilizer application rates and improving the sustainability of agricultural systems.</p

Role of forage legumes mixed cropping on biomass yield and bacterial community composition

Intercropping berseem clover (Trifolium alexandrinum L.) may increase forage yield and free-living N2-fixing bacterial species community. Berseem clover was mixed with Persian clover (Trifolium resupinatum L.) at ratios of 1:0, 3:1, 1:1 and 1:3 and with Persian clover/ annual medic (Medicago regidula cv. Regidula) at ratio of 1:1:1 at Field Crops Department, Faculty of Agriculture, Tarbiat modares university, Tehran, Iran in 2007. Mixed ratio had significant effect on total forage yield. Total forage yield was greatest with a 1:1:1 ratio of clovers to annual medic. Total intercrop yields with clovers/ annual medic at 1:1:1 plants m–2 was 214.37g m–2 DM yields. Mixed cropping increased rhizosphere microorganisms viz. bacteria, free-living N2-fixing bacteria and Azotobacter counts. Free-living N2-fixing bacterial species and Azotobacter populations of 96 g-1 soil*103 cells and 24 g-1 soil*102 cells, respectively, obtained from mixed cropping with 1:1:1 clovers to annual medic ratios

Effect of planting patterns of sunflower on yield and extinction coefficient

We studied the effect of different planting patterns and density of sunflower on yield and on extinction coefficient. The experiment was conducted in the field at the Seed and Plant Improvement Institute, Karaj, Iran on a loamy clay. Planting patterns included wide rows, conventional rows, twin rectangular rows and twin zigzag rows. Populations of plants were at 3 levels including 6, 8 and 10 plants per square meter. The results show that different planting patterns sometimes produced higher yield, but not always. Furthermore, equidistant plant distribution at equal plant densities produced a higher radiation interception and extinction coefficient. Moreover, when row spacing was reduced, grain yield increased. The greatest increase in radiation interception and in the extinction coefficient in response to planting patterns and plant densities was observed in twin zigzag rows of 8 plants m–2. Twin zigzag rows of 8 plants m–2 and conventional rows of 8 plants m–2 produced the highest yield

Effect of density and planting pattern on yield and yield

In order to evaluate competition ability of Grain maize (Zea mays L.) against redroot pigweed (Amaranthus retroflexus L.) a field experiment was conducted at Esfahan on 2003. In this research the effect of corn spatial arrangement on yield and yield components of corn (647 Three Way Cross hybrids) under different levels of redroot pigweed infestation was investigated. Treatments were arranged in a factorial split experiment based on RCBD with three replications. Factorial arrangement of corn densities (74000 and 111000 plant ha-1) and planting patterns (single row, rectangular twin row and zigzag twin row) formed the main plots. Split-plots referred to pigweed densities (0, 4, 8 and 12 plant m-1). Results showed that both grain and biological yield of corn increased as corn density rates increased but rows number per cob, number of grains per row of cob and 1000 grains weight decreased. The effects of planting arrangement on yield and yield components despite rows grain in cob, 1000 seeds weight and harvest index were statistically significant. Corn grain yield and yield components decreased significantly by increasing pigweed density. The effect of redroot pigweed density on corn grain and biological yield loss was predicted using Cousence hyperbolic yield equation. It showed that maximum grain yield loss and biological yield loss happened in single row arrangement and low corn density. Rows number per cob and grain numbers per row in higher corn density treatment showed lower reduction slopes under pigweed competition. In addition, grain rows numbers per cob and corn harvest index in twin arrangement treatments decreased lower than single row treatment under pigweed competition. The results of this research indicated that corn competition ability against redroot pigweed could be increased using dense population (1/5 fold of general density) and zigzag twin row arrangement

Effect of cropping systems and arbuscular mycorrhizal fungi on soil microbial activity and root nodule nitrogenase

Forage legumes are used to enhancement soil fertility of the agro ecosystem. Understanding effect of them on agro ecosystem soil status during when these legumes growing and after that is essential. In one experiment the effects of inoculation with the arbuscular mycorrhizal fungi (AMF), Glomus mosseae, and mixed cropping systems (MCS) on forage biomass yield, nitrogen production, nitrogenase activity and after harvesting on soil microbial activity were studied at various mixed cropping ratios of berseem clover (Trifolium alexandrinum L., B) to Persian clover (Trifolium resupinatum L., P) (B:P = 1:0, 3:1, 1:1, and 1:3). In the second experiment, the effect of treatments on soil microbial activity were studied by soil collection after clover harvesting and 8-week soil incubations in the laboratory. MCS had positive effects on root and shoot dry weight. The effects of AMF on plant yield were positive. AMF affected the fraction root and the vertical root distribution. Plants colonized by AMF showed shorter roots than control plants. At cut 1, with the AMF colonization, the greatest nitrogenase activity (79.61 μmol C2H4 g dwt−1 h−1) of root nodule was observed with B:P = 3:1. At cut 2, the Persian clover plants colonized by G. mosseae in the mixed crop (1:3) had a higher nitrogenase activity (77.38 μmol C2H4 g dwt−1 h−1). The greatest nitrogen accumulation in the aboveground biomass, 23.5 mg g−1 forage dry matter, was obtained with mixed cropping (B:P = 1:1) in the presence of the AMF colonization. Microbial activity measured as substrate-induced respiration and activities of dehydrogenase, alkaline phosphatase, and acid phosphatase enzymes responded positively to AMF colonization; with the greatest activities for B:P = 1:3

Comparison among Different Integrated Nutrition Management for Soil Micro and Macro Elements after Winter Wheat Harvesting and Yield

A comparative field experiment has been conducted in order to study the effect of chemical, organic and integrated nitrogen suppliment on micro and macro nutrient residue after wheat harvesting, at Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. The treatments consisted in three groups that are chemical, organically and integrated of them. Nitrogen was supplied in different proportion from chemical and organic sources. Also, zeolite was applied in two ways: mixed with soil and mixed with cattle manure during composting. Before sowing and after wheat harvesting, macro and micro nutrient availability in the soil were examined. The results showed that, among treatments supplying with 100% nitrogen required from composted cattle manure amended with 10% (w/w) zeolite had the best effect on nutrition residue after wheat production because zeolite decreased nitrogen leaching during the manure composting. Crop yield was not statistically different between fertilizer treatments but the highest seed yield was achieved from supplying 50% nitrogen required from cattle manure compost and 50% by urea amended with 10% (w/w) zeolite. This study demonstrated that composted cattle manure amended with zeolite improves soil fertility after wheat production compared with chemical fertilization