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Faraji A.,Agricultural and Natural Resources Research Center of Iran
International Journal of Plant Production | Year: 2010

An alternative means by which to examine the importance of assimilates supply to flower and pod formation is to analyze the relationships of leaf area index (LAI), above-ground dry matter (ADM), leaf area duration (LAD) and crop growth rate (CGR) around flowering with flower number and pod/flower ratio. For this objective, an experiment was conducted at Agricultural Research Station of Gonbad, Iran in 2005-2006 and 2006-2007. The experiment was a randomized complete block design arranged in split plot. Two cultivars of spring type canola (Hyola401 and RGS003) as subplots were grown at 5 sowing dates as main plots, spaced approximately 30 days apart, to obtain different environmental conditions and assimilates availability around flowering. The experiment was conducted at two conditions, i.e. supplemental irrigation and rainfed. In both main (MR) and branch (MR) racemes, flower number increased as LAI and ADM at the beginning of flowering increased. The reduction in flower number with reduction of LAI and ADM is evidence that canola plants can adjust to carbohydrates availability by altering the number of potential resource demanding sinks. Pod/flower ratio was quadratically related to ADM at the beginning of flowering. A significant positive linear relationship was found between LAD and CGR during flowering period and pod/flower ratio. Therefore, potential and actual pod number was related to cumulative dry matter production of the crop until the beginning of flowering and until the end of flowering, respectively.

Hassanpanah D.,Agricultural and Natural Resources Research Center of Iran
Potato Research | Year: 2010

Water deficit is the most important abiotic stress factor in crop production. Evaluation of the response of different potato cultivars to water deficit stress is necessary to release cultivars for regions with water deficit. A split-plot experiment with three replications was carried out during 2005 and 2006. The main factor consisted of three levels of irrigation (irrigation after 25%, 35% and 50% discharge of the available water, i.e. normal conditions, mild stress and severe stress, respectively), and the split factor included seven potato cultivars (Agria, Savalan, Satina, Caesar, Kennebec, Marfona and Santé). Cultivars Savalan, Caesar and Kennebec had higher total and marketable tuber yield, water use efficiency, and values for stress tolerance indices than the other cultivars, both under mild and severe stress conditions. Cultivars Caesar and Kennebec were selected as tolerant cultivars; cultivars Savalan and Satina were identified as moderately tolerant cultivars whereas cultivars Agria, Marfona and Santé proved to be susceptible to water deficit. © 2010 The Author(s).

Ardakani A.S.,Agricultural and Natural Resources Research Center of Iran
Nematology | Year: 2013

The toxicity of three nanoparticles, silver (AgNP, 20 nm), silicon oxide (SiO2NP, 11-14 nm) and titanium oxide (TiO2NP, 20 nm), to the root-knot nematode, Meloidogyne incognita, was studied in laboratory and pot experiments. Application rates of all nanoparticles were 1.5, 3, 6, 12.5, 25, 50, 100, 200, 400 and 800 mg nanoparticles (ml water)-1 for laboratory experiment to determine their effects on motility and mortality of second-stage juveniles (J2). In pot experiment, 0.02, 0.01, 0.005, 0.0025, 0.00125 and 0.0007% (w/w) of nano-silver and nano-titanium were applied to examine effects on nematode activity and plant growth components of tomato (Solanum lycopersicum). Results showed 100% J2 immobility and mortality in treatments of 800, 400 and 200 mg ml-1 of AgNP; the LC50 for AgNP was 100 mg ml-1. J2 mortality was 48, 16 and 7.3% in 100, 50 and 25 mg ml-1 of AgNP, respectively. J2 mortality was 4.3 and 2% in 800 and 400 mg ml-1 of TiO2NP, respectively. No J2 mortality was seen in all other treatments after 24 h exposure. In a pot experiment, all treatments of AgNP and 0.02% TiO2NP completely controlled M. incognita. Treatments of 0.02, 0.01 and 0.005% of AgNP as well as 0.02% of TiO2NP were toxic to tomato plants and significantly reduced tomato root and stem length and fresh weights in comparison to control. © 2013 Koninklijke Brill NV, Leiden.

Taleshi S.A.R.,Agricultural and Natural Resources Research Center of Iran
Biodiversitas | Year: 2014

Diversity index is the useful criteria for evaluating sustainability of forest ecosystems. Current study carried out in Alder (Alnus subcordata C.A. Meyer) stands that located in north forests of Iran. The aim of the study is express the plant diversity indices and positive role of the trees both natural and plantation forms. Data of Alder trees and associated species were recorded in sample plots which lay down in study area randomly. The abundance, density, percentage of frequency of each species was calculated by standard methods. The results of analysis revealed that, 47 species (21 trees and shrubs species and 26 herbaceous species) were abundant in 80 sample plots both in natural and plantations Alder stands. Whilst the results showed that the number of species in natural area (44 species) was more than plantation stands (37 species). Comparison of species distribution in different physiographical situation showed that some species such as Alnus subcordata, Parrotia persica, Rubus hyrcanus and Prunus sp. recorded in spread rang of physiographic variables as elevation, slopes and aspects. The biodiversity criteria as Shannon H' and Simpsons D and 1/D indexes showed that they were more in natural stands than plantation areas.

Afzalinia S.,Agricultural and Natural Resources Research Center of Iran | Zabihi J.,Shiraz University
Soil and Tillage Research | Year: 2014

Area cultivated using conservation tillage methods has recently increased in Iran and soil compaction increment is one of the most challenging issues in this new technology. In addition to the soil compaction status at the end of growing season, soil compaction variation during the growing season is also important because of its potential effect on the crop growth and yield. Therefore, soil compaction variation during the corn growing season under different tillage methods and its effect on the crop yield was investigated in this study. The research was conducted in the form of a split plot experimental design with nine treatments and six replications. Main plots were tillage methods including: (1) conventional tillage method (CT); (2) reduced tillage (RT); and (3) zero tillage or direct drilling (ZT). Soil depth ranges of 0-0.10, 0.10-0.20, and 0.20-0.30. m were considered as sub plots. Soil bulk density (BD) and soil cone index (CI) were measured during corn growth season (eight measurements for bulk density and five measurements for cone index) as indices of soil compaction. Corn silage yield, thousand kernels weight, and grain yield were also determined in this research. Collected data were analyzed using SAS statistics software and Duncan's multiple range tests were used to compare the treatments means. Results indicated that tillage methods and soil depth had a significant effect on the soil bulk density so that the maximum soil bulk density was obtained from ZT method and soil depth range of 0.10-0.20. m. The difference between soil bulk densities in different tillage methods was statistically significant from the beginning of growth season to two month after the first irrigation (sixth measurement); while, this difference was not significant from the sixth measurement to the end of growth season. Soil cone index was also significantly affected by tillage methods and soil depth in such a way that ZT method and 0.20-0.30. m soil depth range had the maximum cone index. Although, the difference between tillage methods for corn yield and yield components was not statistically different, ZT method decreased corn thousand kernels weight, silage yield, and grain yield compared to the CT method for 11.1, 2.4, and 18.2%, respectively. © 2013 Elsevier B.V.

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