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Aerial parts of blessed thistle ( Cnicus benedictus L.) contain high amounts of phytochemicals and would be improved through varying agronomic management practices such as N rate and plant density. The objective of this study was to investigate the effect of different N fertilizer rates and plant densities on agronomic performance, photosynthetic capacity, leaf area index, carbon to N ratio (C/N), cnicin content, total phenol and flavonoids, and antioxidant activity in blessed thistle. A two-year field experiment was conducted in a semi-arid region in Iran in 2013 and 2014. The experiment was arranged as a randomized complete block design with a factorial arrangement and three replicates. Treatments consisted of four N rates (0, 50, 100 and 150 kg N ha −1 ) combined with five plant densities (5, 10, 15, 20 and 25 plants m -2 ). Total chlorophyll and straw N contents as well as photosynthesis rate significantly increased by either 50 or 100 kg N ha −1 . The significant reductions of straw N in 2013 and photosynthesis rate in both years were found with increasing plant density. Total phenol, flavonoid contents, C/N ratio and antioxidant activity were decreased as a result of increased N rate. The highest cnicin contents and yields were obtained from high plant densities under low N rates. This response may be attributed to N and plant density compensation effect. The enhancement in secondary metabolites and antioxidant activity were associated with high C/N ratio and low N contents, and accompanied by a decrease in chlorophyll content that showed a positive correlation with photosynthesis and biomass yield. The study demonstrates that increasing plant density (>15 plants m −2 ) with a low N rate (50 kg N ha −1 ) could be suitable for both biomass and phythochemichal production of blessed thistle. Furthermore, this study suggests that blessed thistle has the ability to achieve higher biomass and yield of cnicin in poor soils and unfavorable conditions. [ABSTRACT FROM AUTHOR]

A field experiment was carried out in a semi-arid region of Iran during the 2006–2007 growing season to investigate canola seed yield as affected by nitrogen (N) and natural zeolite (Z) rates. This experiment studied N efficiency and N leaching loss in a sandy soil. Experimental treatments consisted of a factorial combination of three N levels (90, 180, and 270 kg N ha−1) and four zeolite rates (0, 3, 6, and 9 t zeolite ha−1). The result showed that the greatest seed yield (2452.3 kg ha−1) was obtained from the N270Z9 treatment whereas the control treatment (N0Z0) produced the lowest seed yield (1038.3 kg ha−1). Moreover, use of 270 kg N ha−1 without zeolite (N270Z0) led to the greatest amount of N leaching loss (144.23 kg ha−1). Zeolite application clearly reduced N leaching loss in all N rates. This justified low N-use efficiency in high N applications. More N uptake and more canola seed yield is attributed to zeolite application. [ABSTRACT FROM AUTHOR]

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 sratistically 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. [ABSTRACT FROM AUTHOR]