1 1562-5540 Crop Science Society of Iran 788 Special Effect of defoliation timing on tuber yield, quality and storage capability of two potato (Solanum tuberosum L.) cultivars 1 12 2017 19 3 181 194 22 11 2017 22 11 2017 This experiment was conducted in 2010 and 2011 to investigate the effect of defoliation timing on yield, quality traits and storage capability of tuber in potato crop. The experiment was carried out as factorial arrangement in randomized complete blocks design with two factors and three replications. Experimental factors comprised defoliation timing at five levels; complete removal of haulm in 7, 14, 21 and 28 days before physiological maturity phase of potato crop and control treatment haulms were not removed Second factor was two cultivars of potato, “Agria” and “Savalan”. Tubers were harvested in two weeks after defoliation in all treatments. Total tuber yield, number of tuber in different sizes (large, seed and small tuber) were weighed and counted. Some quality characteristics of tuber such as dormancy longevity, dry matter percentage, reduced sugar of tuber and amount of vitamin C were also measured.  Mean comparisons showed that highest yield and large tuber were achieved in control (not defoliated) followed by defoliated 7 days before physiological maturity phase as they were not significantly different. These two treatments produced higher total yield (35.8 and 34.3 ton.ha-1, respectively), but were not significantly different from defoliated treatment 14 days before physiological maturity. In term of seed size tuber, the highest amount (14.44 number.m-2) was counted in defoliated 14 days before physiological maturity. Defoliation in 7 and 14 days before physiological maturity phase produced higher amount of vitamin C (50.23 and 48.35 mg.100g-1Fw, respectively), and were not significantly different from control. The highest amount of reduced sugar (3.04 mg.100g-1Fw) achieved in defoliation 28 days before physiological maturity phase. The tubers produced in defoliation in 7 and 14 days before physiological maturity phase as well as control had longer tuber dormancy. In conclusion, defoliation in 7 and 14 days before physiological maturity phase were superior treatments in respect with total yield and seed tuber size as well as other quantitative and qualitative characteristics of tuber. Therefore, these two defoliation timing can be recommended for seed tuber potato production.
789 Special Quantifying response of seedling emergence to temperature in rapeseed (Brassica napus L.) under field conditions 1 12 2017 19 3 195 207 22 11 2017 22 11 2017 Determination of response function of seed germination and seedling emergence to temperature and obtaining cardinal temperatures (base, optimal and maximum) and biological day requirement (minimum day number for seed germination and seedling emergence under optimal temperature and moisture conditions) for emergence is important for crop simulation modeling.  This study was carried out to survey seedling emergence response to temperature in five rapeseed cultivars that were sown on 12 sowing dates under Gorgan environmental conditions (2013-2014). Three regression models including beta, segmented and dent-like were used to describe the response of seedling emergence rate to temperature. Root mean square of error, coefficient of determination, correlation coefficient and regression of predicted versus observed values were used to develop the appropriate model. Segmented model was superior compared to beta and dent-like models to achieve the objective of this study. Estimated cardinal temperatures using appropriate model were 3.2, 26.8 and 40˚C for base, optimum and maximum temperatures, respectively. Estimation of biological day requirement in sowing depth of 2 cm showed 4.5 days. The result showed that there is no significant difference for cardinal temperatures and biological day requirement among cultivars. It was concluded that segmented model can be used to quantify the response of rapeseed sedling emergence to temperature and to obtain cardinal temperatures of emergence and thermal time or time to emergence. These parameters are required to develop prediction models for rapeseed seedling emergence under diverse temperature conditions. 790 Special Identification of plant characteristics related to seed yield of faba bean (Vicia faba L.) genotypes using regression models 1 12 2017 19 3 208 219 22 11 2017 22 11 2017 Quantification of plant charatcteritics associated with yiled increase is important in crop breeding programs. Regression models can be used for this purpose. Different genotypes of faba bean were evaluated using a randomized complete block design with three replications in 2014-2015 in Agriculture Research Station of Gorgan, Gorgan, Iran. Regression model revealed that faba been seed yield can be increased from 1665 kg.ha-1 to 2880 kg.ha-1 (1215 kg,ha-1 increase). It was found that this increase can be achieved by manipulation of four plant traits, i.e., plant height, pod number per plant, seed number per pod, and days to flowering. There was no significant negative correlation between the traits. Optimizing of these traits, within the observed range in the field experiment, can increase faba bean seed yield by 1215 kg.ha-1. The contribution of each trait in this increase was estimated: plant height by 503 kg.ha-1, pod number per plant by 344 kg.ha-1, seed number per pod by 327 kg.ha-1 and days to flowering by 41 kg.ha-1. It was concluded that using regression models would be helpful for increasing the efficiency of faba been breeding programs in Gorgan, Iran. 791 Special Economic analysis of effect of water and nitrogen levels on grain yield and yield components of maize (Zea mays L.) cv. SC 704 1 12 2017 19 3 220 238 22 11 2017 22 11 2017 To study effects of irrigation water and nitrogen fertilizer levels on grain yield and its components of maize (cv. SC704) and to evaluate economic efficiency of experimental treatments a filed experiment was carried out as split plot arrangement in randomized complete block design in 2014 and 2015 growing seasons at experimental field of Agriculture and Natural Resources Campus, Razi University, Kermanshah, Iran. Four irrigation water levels (60, 80, 100 and 120% of maize water requirement) were assigned to main plots, and four nitrogen fertilizer levels (40, 70, 100 and 140% of recommended levels based on soil test) were randomized in sub-plots. Results showed that regardless of nitrogen fertilizer levels, application of 120% of the maize water requirement, 8760 kg.ha-1 grain was produced and with reducing water requirements to 20, 40 and 60%, grain yield decreased by 10, 37 and 65%, respectively. Irrigation water and nitrogen supply simultaneously increased the total dry weight, grain yield and grain protein. At lower levels of irrigation water, there was no significant difference in grain yield between nitrogen fertilizer levels. However, application of 100 and 120% of the maize water requirement, nitrogen fertilizer up to recommended levels increased grain yield by its affect on ear size and yield components. Therefore, by application of 120% of maize water requirement and 100 and 140% of nitrogen requirement, 9340 and 9280 kg.ha-1 maize grain yield was achieved. Grain yield in these nitrogen levels and 100% of maize water requirement were 8770 and 8300 kg.ha-1. The highest gross and net return per hectare (82.94 and 48.99 million Rials in 2014 and 86.70 and 45.04 million Rials in 2015, respectively) were obtained by application of 120% of maize water requirement and 100% of nitrogen requirement. Optimum level of water economic efficiency (4200 and 3670 Rials.m3 in 2014 and 2015) and nitrogen (71060 and 48650 Rials.kg-1 in 2014 and 2015) were obtained by application of 100% of maize water requirement. The results also showed that with increasing nitrogen fertilizer application, economic efficiency of nitrogen decreased and nitrogen application up to 70% of recommended level improved economic efficiency of maize. Although the highest grain yield and net income were obtained by application of 120% of maize water requirement and 100% of nitrogen requirement, but appropriate combination of irrigation water and nitrogen levels is recommended considering the importance, price changes, economic productivity and environmental constraints of each inputs. 792 Special Effect of application of zeolite and nitrogen fertilization on growth, seed yield and water productivity of fenugreek (Trigonella foenum-graecum L.) under drought stress conditions 1 12 2017 19 3 239 254 22 11 2017 22 11 2017 To study the effects of drought stress, nitrogen fertilization and zeolite on some morphological, phenological and agronomic traits of fenugreek, a split factorial experiment was laid out in randomized complete block design with three replications in 2014 and 2015 growing seasons at research field of Tarbiat Modares University, Tehran, Iran. Five irrigation regimes (non drought stress; mild drought stress during the vegetative and reproductive stages, respectively; severe drought stress during the vegetative and reproductive stages, respectively) were randomized in main plots. Subplots were six factorial combinations of three nitrogen fertilization levels (untreated plots, vermicompost fertilizer at a rate of 2.7 ton.ha-1 and Urea fertilizer at rate of 11 kg.ha-1) and two zeolite levels (0 and 9 ton.ha-1). Results showed that in both growing seasons, drought stress significantly decreased all traits in comparision with control, and vermicompost fertilizer and zeolite reduced the negative effects of dought stress. The highest seed yield was obtained in non-water stress with vermicompost (903.1 kg.ha-1) and application of zeolite and vermicompost (568. 09 kg.ha-1). In the first growing season, grain yield declined by 24% and 76% with increasing deficit water stress in vegetative and reproductive stages, respectively.In the second growing season, these decreases were 31% and 54%, respectively. It was concluded that application of vermicompost and zeolite extended the duration of availability of water and nitrogen and led to increase seed yield and its component as well as water productivity in fenugreek. 793 Special Assessment of branching phenomenon in the female parental inbred line of hybrid sunflower (Helianthus annus L.) cv. Azargol 1 12 2017 19 3 255 269 22 11 2017 22 11 2017 Maintenance of genetic purity of parents of hybrid is important in hybrid development and commercialization. Branching phenotype in maternal line of Azargol, an Iranian sunflower hybrid, is a challenging. This experiment was carried out to understand thae basis of this phenomenon, and included three phases. Genetic phase, all possible crosses between plants possessing one, two, and/or three heads (suspicious plants) were made during 2013 to 2015 in Seed and Plant Improvement Institute, Iran and their progenies were backcrossed to single-headed parent. Molecular phase, previously published branching-linked molecular markers were evaluated on individuals from the parents, original single –headed, and original multi head genotypes. Bioinformatics phase, presence of environmentally responsive cis-regulatory elements in the promoters of branching genes characterized in other plant species were investigated. Genetic analysis indicated that progenies of all crosses (239 indivudials) appeared to be single headed plants. Similar banding pattern was observed among suspicious plants and original single-headed lines, but differed from original multi head genotypes. At least one cis-regulatory elements responding to cold and drought stress were found in the promoters of branching genes in other plant species. Results of the three phases of this experiment revealed insufficient evidence to attribute the branching phenotype in the inbredline of interest to genetic factors.