فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 52 (زمستان 1398)

To study the eco-physiology of new winter varieties of rapeseed (six lines ready for introduction, along with Ahmadi, native variety, as control), for drought stress of the end of the season were evaluated with two levels of planting dates, including the usual sowing date (October 12th) and late planting date (October 27th), and irrigation with two levels including normal irrigation (control) and cutting off irrigation at the siliquing stage studied in a factorial split plot experiment based on a randomized complete block design with three replications for two years (2014-2015 and 2015-2016) at the Seed and Plant Improvement Institute, Agricultural Research Organization in Karaj. Cultivar L72 had higher palmitic acid content in both planting dates. Normal irrigation and October 12th planting date had the highest oleic and linoleic acids, 66.2 and 18.34%, respectively. The highest erosic acid (0.27%) belonged to cultivar HW3 and on October 12th and the highest linolenic acid was obtained (6.95%) by cultivar L72. The lowest linoleic acid was obtained on October 27th by cultivar HW3. Under water stress condition, seed glucosinolate content was 14% more than the normal irrigation. The highest seed yield (4231.2 kg.ha-1) was obtained from sowing date of October 12th from cultivar L72 and the lowest of seed yield was obtained on October 27th from cultivar HW3. The highest seed oil percent (46.54%) and oil yield (2576.6 kg.ha-1) were obtained on October 12th from cultivar L72 and the lowest of these triats were obtained on October 27th from cultivar HW3. In general, the results showed that under stress condition, cultivar L72 produced highest seed and oil yields in both planting dates.

To study the relationships among traits of thyme ecotypes, two experiments under non-stress and drought stress conditions were carried out using randomized complete block design with four replications in Abarkouh during 2017-2018 cropping season. Correlation analysis was used for evaluation of relationships among traits. Stepwise regression and path analysis were used for determination of effective traits on shoot dry weight and for determination of direct and indirect effects on shoot dry weight, respectively. Factor analysis was used for identifying factors that produce special correlations among measured variables. Correlation coefficients among traits showed that there were significant positive correlation among traits like shoot fresh and dry weight with maximum and minimum diameter of canopy, canopy area, leaf length, number of stems per plant and essential oil yield under both conditions. The result of stepwise regression showed that canopy area, leaf width, leaf length, number of flower in inflorescence and number of days to 50% of flowering under non-stress condition and canopy area, leaf width, leaf length and number of days to 50% of flowering under stress condition were entered to the stepwise regression model. The result of path analysis under both conditions showed that canopy area had the highest direct and positive effect on shoot dry weight and leaf width and negative effect on shoot dry weight. Based on factor analysis, three factors were selected and these factors explained 76% of total variation under both conditions and traits such as shoot fresh and dry weight, maximum and minimum diameter of canopy, canopy area, leaf length, number of stems per plant and essential oil yield were main components of these factors.

To determine resistance of four species forage crops to drought stress an experiment was conducted for two years (2016-2017) in Kerman – Iran. In this study a randomized complete block design arranged in a split plot experiment with four replications was used. Drought stress treatments consisted of normal, moderate and severes drought levels (80, 130 and 180 mm cumulative pan evaporation respectively) were assigned to main plots and four forage plant types (maize, kochia, millet and sorghum) to subplots. Results indicated that with increasing of drought stress, leaf relative water content decreased but MDA (malondialdehyde) content increased. Among the four forage plants under study, kochia had the lowest MDA content. Chlorophyll a under moderate and severe drought stresses decreased by 16.3% and 20.7% respectively, as compared to normal drought. Kochia, in both years and under all levels of drought stresses, had the highest sodium percent in shoots. Sorghum had the highest amount of potassium content in shoot, as compared to other plants under severe and moderate levels of drought stresses. Sorghum produced the highest the forage yield at all levels of drought stresses and it produced highest fresh and dry (101241 kg.ha-1 and 30181 kg.ha-1) respectively under normal irrigation. Increasing drought stress resulted in the reduction of forage yield of all plant under study but yield reduction in kochia was lower than the yield of other plants. Millet and kochia with %11.9 and %9.82 crude protein contents respectively produced higher crude protein contents in this respect. Based on the results of this study, sorghum produced highest forage yield, millet good quality forage and kochia was the most tolerant plant to drought stress condition.

Cadmium is one of the soil primary pollutants which is categorized as heavy metals and brassicaceae family are able to accumulate high amounts of heavy metals such as cadmium by producing high amounts of dry matter. In order to evaluate fatty acids variation, seed oil percentage, yield and yield components of black mustard as affected by growth promoting rhizobacteria and growth regulators under cadmium stress condition, a factorial experiment based on randomized complete block design was conducted at the Research Green House of Mohaghegh Ardabili University with four replications. Experimental treatments were two cadmium levels (0 and 100 milligrams per kilograms of soil), three rhizobacteria levels (control, Azospirillum and Pseudomonas) and three growth regulator levels (control, salicylic acid and brassinosteroid). Mean comparisons indicated that cadmium treatment decreased pods number per plant, grain number per pod, root dry weight, seed oil percentage, oleic, linoleic, eicosenoic and erucic acid percentages, significantly. Growth promoting rhizobacteria increased all of above mentioned parameters significantly, where as, it decreased palmitic acid content. Plant growth regulating sprays resulted in a significant increment in plant yield, shoot and root dry weight, seed oil percentage and all kinds of unsaturated fatty acids while it reduced stearic acid content and saturated fatty acids. The interaction of cadmium×rhizobacteria indicated that both cadmium levels used, along with rhizobacteria treatment, increased plant yield, thousand seed weight, shoot dry weight, linolenic acid and unsaturated fatty acids, where as decreased stearic and saturated fatty acids, significantly. In general, the effects of cadmium on these traits were different. Interaction of cadmium×growth regulators, spray application of growth regulators, under both cadmium levels, reduced palmitic acid and induced unsaturated fatty acids significantly and cadmium application had an inverse result.

Malnutrition due to low micro-nutrients content in cereals and lack of diversity of food stuffs are serious health problem in developing countries, including Iran. Due to the important nutritive role of wheat in these countries, researchers are trying to produce wheat grains with higher nutrients contents like iron, zinc, ascorbic acid and protein, along with low phytic acid content and Zn/PA ratio to limit malnutrition. Because of significant role of Zn on the metabolism of carbohydrates and proteins; the effects of foliar application of Zn on the quality and yield of wheat grains was studied. In this study six wheat cultivars were planted at a farm in Tastaghar village located in Hashtrood county, during early fall of 2016 in split plot experiment based on randomized complete block design. Treatments used were six wheat cultivars (Baran, Tak-Ab, Sardari, Ohadi, Homa and Azar 2) and leaf foliar application of Zn with four levels (control, during beginning of stem elongation and stem elongation+anthesis stages). Zn foliar treatments were applied in the evenings by a portable pump sprayer. The results revealed that the foliar application of Zn increased seed yields of the cultivars under study. Moreover, protein, Zn and ascorbic acid content of the seed were also increased significantly (P≤%5). However, phytic acid content and Zn/PA ratio were decreased as compared to control. Overall it can be said that, foliar application of Zn had positive impact on the seed yield, proteins, Zn and ascorbic acid contents. It can be concluded that the foliar application of Zn on wheat would improve the seed yield and some qualities of wheat cultivars. It would be advisable to extend continuing this kind of studies to overcome malnutrition problems of area. Further studis is recommended to substantiate the results.

To study the effect of winter planting and zinc spraying on yield and yield components of canola (Brassica napus) cultivars, a factorial split plot experiment based on randomized complete block design with three replications was conducted for two years (2014-2015 and 2015-2016 cropping seasons) at the experimental farm of Seed and Plant Improvement Institute of Agricultural Research, Education and Extension Organization of Karaj, Iran.. In this experiment, winter plantings with three levels (24th February, 6th, and 16th March) and Zinc factors with two levels, including application of zinc sulfate spray and spray with pure water assigned to main plots and spring cultivars, including RGS003, Zafar, Julius, Jerry, Zabol 10, Hyola 4815 to subplots. The results of combined analyses of data showed that the effect of year, planting date, zinc spray, cultivar and planting date × cultivar interaction effects on qualitative traits (grain glycosinolate content and fatty acid percentages) in different planting dates and cultivars were significant at 1% level of probabilities. According to the results, the highest (66.89%) and lowest (66.02%) oleic acid percentages belonged to zafar and zabol10 cultivars, respectively. Planting dates × cultivar interaction effect on the glucosinolate content indicated that the lowest glucosinolate content produced by Zafar (8.313 mg.g-1) and hyola4815 (8.567 mg.g-1), when they were sown on March 16th. The results of this experiment showed that delayed planting, decreased percentages of palmitic, linoleic and oleic acids of seed oil, while increased percentages of linolenic and erousic acids and glycosinolate contents.

To evaluate agronomical characteristics and yield of dragon head by using different levels of nitrogen and microelements (Fe, B, Zn), a factorial experiment based on randomized complete block design with three replications was conducted in Khoy, during 2016 and 2017 growing seasons. The first factor consisted of three levels of recommended nitrogen fertilization (1- before planting, 2- one half before planting+15 days after planting, 3- one third before planting+ one-third one month after planting+ one-third 45 days after planting) and the second factor was the use of microelements with five levels including non-consuming treatments, iron with boron, iron with zinc boron, zinc. Nitrogen consumption resulted in significant effect on stem diameter, 100 seed weight, fresh weight of plant and essential oil yield. According to the results, growth and yield increase were observed using fertilizers. Therefore, the highest plant height was in two stages, the fresh yield of 10805.80 kg.ha-1, in three stages, essential oil percentage of 0.59% and essential oil yield of 16.33 kg.ha-1 in nitrogen application in two stages and iron, boron and was observed. Although the second treatment of nitrogen (half before planting and half after sowing) along with that of boron and zinc micronutrients, the highest percentage of essential oil was 0.59%, but the consumption of other micronutrients also increased the essential oil content. Meanwhile, the highest fresh yield of nitrogen in nitrogen application was obtained at 10805.7 kg.ha-1 during three stages. It can be concluded that in growing dragonhead, nitrogen should be used in several stages and micronutrients usage also improves the quality and quantity of plant yield.

To investigate the effect of duration of weed interference on yield and yield components of cumin grown under conventional and organic condition, a field experiment was conducted in a private farm in Sabzevar in 2017-2018. A split plot experiment based on a randomized complete block design with three replications was conducted. Factors were conventional and organic growing was considered as the main factor and duration of weed interference (0, 2, 4, 6 weeks after emergence and weedy) as subplots. The results showed that conventional farming in terms of weed density, weed dry matter, plant height, lateral branch number, number of seed per umbrella, biologic and seed yield were better than organic farming, while, number of umbrella per plant under organic farming was higher than that of conventional farming. Increasing duration of interference decreased plant height (20.21%), lateral branches (42.85%), the number of umbrella per plant (47.91%), the number of seeds per umbrella (37.5%), biological yield (33.96%) and seed yield (43.90%). Fitted logistic regression function coefficients showed that the onset of yield loss was earlier (11 days after emergence) in conventional condition while in organic condition it was postponed to 17.5 days after emergence. Overall, the results showed that weed interference, under both conventional and organic conditions, reduced seed yield. Weed interference under organic farming delayed 4 weeks and under conventional condition to 2 weeks after cumin emergence and yield reduction was not significant. Thus, control of weeds in conventional conditions should commence from 12 days after emergence and under organic conditions from 18 days after emergence.