Effects of density and relative time of pigweed (Amaranthus retroflexus) emergence on yield of potato (Solanum tuberosum)

For create of food security is essential increasing of efficiency and more productivity strategic products such as potato. In order to investigate the effects of density and relative time of pigweed emergence on potato, a factorial field experiment was conducted during 2014 based on randomized complete block design with three replications at the Research Station of Borojen, Chaharmahal and Bakhtiari, Iran. Treatments were combination of three different pigweed densities (5, 10 and 15 plants/m2) and relative time of pigweed emergence (4 and 8 days before potato, emerged with potato, 4 days after potato emergence). Results indicated that the effects of density and relative time of emergence of pigweed was significant on number of branches per plant, plant height, number of tubers per square meter, biological yield and tuber yield of potato. Also, the interaction of between experimental factors was significant on the biological yield and tuber yield of potato. The earlier emergence and pigweed density led to reduce number of branches per node,biological yield and tuber yield and increase plant height of potato. The presence of weeds caused reduce the size and number of potato tubers. Procedure of decreasing biological yield and tuber yield potato was different with density increasing of pigweed in various relative time of emergence treatment. The highest (39.8 t ha-1) and the least (18.4 t ha-1) tuber yield were related to density of five plants/m2 and emergence at 4 days after potato and density of 15 plants/m2 and emergence at 8 days before potato treatments, respectively

Interaction of N Residues of Maize Cropping and N Fertilizer on Seed and Oil Yield of Rapeseed

In order to determine the interaction of residual nitrogen (N) and different N rates on seed and oil yield of rapeseed, an experiment was conducted at Shahrekord University, Shahrekord, Iran, in 2008-2009 growing season. The experimental design was split plots arranged in randomized complete block design with three replications. Seven treatments of residual N (217, 435 and 652 kg/ha from urea fertilizer 6.1, 12.2 and 18.3 ton/ha from broiler litter and control: no-fertilizer) as main plots, and different levels of nitrogen (0, 60, 120 and 180 kg/ha N) as subplots were compared. Results showed that the highest number of seeds per pod and 1000-seed weight were obtained with residual N of 12.2 ton/ha as broiler litter of previous cropping. The applied N in rapeseed cropping resulted in a significant increase in number of seeds per pod, but oil content was significantly decreased. A significant interaction was observed between N residues of previous crop and applied N on number of pods per plant, seed yield and oil yield. The highest seed and oil yields were obtained with N residues of 12.2 ton/ha broiler litter and 120 kg/ha N in rapeseed cropping. In general, application of large amount of chemical fertilizer in maize cropping reduces the potential of rapeseed yield. However, application of broiler litter not only provides residual N for rapeseed, but also reduces fertilizer costs

Effect of Osmotic Stress on Seed Germination Indices of Nigella sativa and Silybum marianum

Evaluation of medicinal plants to drought and salt stress tolerance, in an attempt to plant them under drought and saline regions, is of utmost importance. Environmental stresses, especially drought and salt, reduce the global crop yields more than other factors. Selection of drought tolerant crops at germination stage, usually is, the fast and low cost method. In order to study the effect of osmotic stress on germination indices of black cumin and milk thistle, an experiment carried out in a completely randomized design with four replications at the Seed Technology Laboratoary of Yasouj University in 2008. Treatments were 0 (as control), -2.4, -4.8, -7.2 and -9.4 bar osmotic potentials created by using PEG 6000. Results showed that, decreasing of osmotic potential reduced speed of germination and its percentage, root and shoot lengths and dry matter in these two plants. Black cumin showed higher tolerance, to -4.8 bar osmotic potential, as compared to milk thistle. However, milk thistle showed higher tolerance to drought stress, up to this osmotic potential (-4.8 bar), compared to black cumin. Milk thistle had lower germination speed and percentage at higher drought stress as compared to black cumin. Generally, milk thistle showed better growth and survival than black cumin due to its higher root and shoot length and dry matter

Evaluation of Some Physiological Characteristics of Spring Rapeseed Genotypes under Drought Stress

This experiment was conducted in 2010 in order to study the effect of drought stress on proline, soluble carbohydrates, relative water content, concentration of potassium and sodium of leaf, electrolytes leakage from leaves and grain yield of spring rapeseed cultivars in Research Greenhouse of Yasouj University, Yasouj, Iran. The experiment was factorial, based on completely randomized design with three replications. In this research, six genotypes of spring rapeseed (CR3189, CR3250, Kosa Kroko, Marnoo and Regent) and irrigation treatment at three levels (irrigation after 10, 40 and 70% depletion of soil moisture) were studied. Results showed that interaction of irrigation and genotype had significant effect on all traits, except potassium concentration. Comparison of average values of treatments showed that in all genotypes, the proline content, soluble carbohydrates, sodium concentration and electrolytes leakage from leaves were increased due to drought stress, but potassium concentration, relative water content and grain yield were decreased. Among the genotypes, at all three levels of irrigation, the maximum grain yield (0.86, 0.58 and 0.34 g/plant, respectively) was related to Kosa cultivar, which had less electrolyte leakage and sodium concentration, but higher proline content, potassium concentration and relative water content. Regent cultivar had the lowest potassium concentration, proline, relative water content and grain yield and also had the highest electrolytes leakage and sodium concentration. The lowest grain yield at 10% irrigation level (0.47 g/plant) was in CR3250 genotype and at 40% and 70% irrigation levels (0.33 and 0.19 g/plant, respectively) was observed in Regent genotype. Overall, based on the obtained results, Kosa and Regent cultivars were identified as tolerant and susceptible to drought stress, respectively

Interaction Effects of Planting Date and Weed Competition on Yield and Yield Components of Three white Bean Cultivars in Semirom

Unsuitable planting and weed competition are the most important factors that greatly reduce the yield of bean. In order to study the effect of planting date on yield and yield components of three white bean cultivars in weed infest and weed free condition a factorial experiment with randomized complete block design and three replications was carried out at Semirom in 2009. The treatments were planting date (May10, May 25 and June 9) and white bean cultivars (Shekofa, Pak and Daneshkade) and two levels of weed infestation (weedy and weed free). Results showed that planting date, weed competition and cultivars had significant effects on yield and yield components of white bean. The 30-day delay in planting date reduced the number of pods per plant, seeds per pod, 100 seed weight and biological yield of white bean cultivars, 22.5, 18, 20.1 and 22.5 percent respectively. Also weed competition, reduced the number of seeds per pod, 100 seed weight and biological yield respectively by 13.5, 5.7 and 27.1 percent. Result of planting date and weed competition interaction effects indicated that the weed competition decreased grain yield (53%) in third planting date more than others and delay in planting date was companion with increasing weed density and dry weight in flowering stage of bean. Also Shekofa cultivar had highest grain yield (3379 kg/ha) at the first planting date and weed free condition

Effect of Foliar Application of Phosphorus and Water Deficit on Yield and Yield Components of Winter Wheat (Cultivar Alvand)

In order to study the effects of foliar application of phosphorus (P) and water deficit on yield and yield components of winter wheat (Triticum aestivum L., cv. Alvand), a split-plot experiment, with completely randomized blocks design and three replications, was carried out at the Research Farm of Boyer Ahmad Agricultural and Natural Resources Research Station, 13 km west of Yasouj, in 2008-2009. The main plots were irrigation at three levels (1- full irrigation (control), 2- deficit irrigation from the stem elongation to booting stage, and 3- deficit irrigation from booting stage to the end of growth period) and the subplots were five levels of foliar application of P fertilizer (0, 3, 6, 9 and 12 kg/ha KH2PO4). The results showed that the effects of different irrigation regimes and foliar application of P were significant on all traits, and their interaction was significant on plant height, number of grain per spike, grain yield and biological yield. Full irrigation and foliar application of 6 kg/ha P produced the highest grain and biological yield (6000 and 14170 kg/ha, respectively) and deficit irrigation from the stem elongation to booting stage without foliar application of P produced the lowest grain and biological yield (2920 and 8219 kg/ha, respectively). Foliar application of P affects significantly the evaluated traits only in drought-stress treatments and its effect was not significant in full irrigation treatment. In general, foliar application of 9 kg/ha P compensated the losses in wheat due to drought stress

Study of the Quantitative and Qualitative Traits of Four Soybean (Glycine max L.) Cultivars under Different Sowing Dates in Shahrekord Region

To study the effect of sowing date on quantitave and qualitative traits of soybean in Shahrekord region, an experiment was performed as split plot based on randomized complete blocks design with four replications at Agricultural and Natural Resources Research Centre of Chaharmahal-va-Bakhtiari, Shahrekord, in 2008. Four sowing dates (May 5, May 20, June 4 and June 19) and four varieties (M9, M7, L17 and Williams) were selected as main and sub plots, respectively. Results showed that maximum number of pods per plant, seeds per plant and biological yield were observed for M9 cultivar at 20 May sowing date. This sowing date had also the highest seed weight, oil percent and biological yield comared to other dates. The maximum protein percent was observed in June 4 (37.6%) and June 19 (38.4%) sowing dates. There was no significant difference between cultivars for oil and protein percent. There was no significant difference between three planting dates of May 5, May 20 and June 4 for seed yield. But minimum seed yield belonged to June 19 sowing date. In general, the M9 cultivar, with 2896.1 kg/ha seed yield, and then M7 cultivar with 2597.7 kg/ha seed yield, are recommendable as suitable soybean cultivars for cultivation in Shahrekord region

Effect of Planting Date on Physiological and MorphologicalCharacteristics of Four Canola Cultivars in Yasouj

In order to study the physiological and morphological characteristics of canola cultivars at different planting dates, an experiment was carried out in 2008-2009 at the Agriculture Research Station of Yasouj. A factorial with Randomized Complete Block Design with four replications was conducted. Four planting dates (September 12, September 22, October 2 and October 12) and four cultivars (Zarfam, Okapi, Elite and SLM-046) were used in this study. Results showed that cultivars and planting dates had significant effects on more characteristics. In addition, interaction of planting date and cultivar was significant on plant height, height to lowest silique, number of branches, growth indices and grain yield. Zarfam and Elite cultivars had lower initial fluorescence (Fo) and higher maximum fluorescence (Fm) and photochemical capacity of photosystem II (Fv/Fm) than Okapi and SLM-046 cultivars. Elite cultivar at September 12 planting date had the highest plant height (173 cm) and height to lowest silique (87.5 cm) and Okapi cultivar at October 12 planting date showed the lowest plant height (91 cm) and height to lowest silique (43.7 cm). At September 12 planting date, Elite cultivar had the greatest leaf area index (5.21) and grain yield (5231 kg/ha). At other planting dates, Zarfam cultivar because of priority in leaf area index, crop growth rate and total dry matter have the greatest grain yield than other cultivars. In general, seems at September 12 planting date, Elite cultivar and for delayed sowing, Zarfam cultivar had better reaction than other cultivars