فصلنامه علوم زراعی ایران
سال بیست و یکم شماره 2 (پیاپی 82، تابستان 1398)

To evaluate the effect of deficit irrigation and within row spacing on grain yield and yield components of grain sorghum promising lines, an experiment was conducted as split plot-factorial arrangement in randomized complete block design with three replications in 2015 and 2016 at the research field of Seed and Plant Improvement Institute, Karaj, Iran. Main plots consisted of three irrigation regimes (irrigation applied after 60, 120 and 180 mm cumulative evaporation from Class A pan) and sub-plots included factorial combination of three levels of within row spacing [8, 12 and 15 cm (21, 14 and 11 plant.m-2, respectively)] and three promising lines of grain sorghum (KGS23, KGS32, and KGS36). Combined analysis of variance showed that the sorghum prmising lines differed significantly for grain yield. The highest (5333 kg.ha-1) and lowest (4011 kg.ha-1) grain yield obtained from promising lines KGS23 and KGS32, respectively. The results showed that the response of the grain sorghum promising lines to the irrigation regimes was different, and KGS23 was significantly superior in comparison with the other two lines for most of the studied traits. In addition to high grain yield and desirable morphological traits, KGS23 showed adaptibility to deficit irrigation conditions. KGS36 ranked next to KGS23 for grain yield and tolerance to deficit irrigation. The effect of within row spacing on forage yield and biological yield was significant. Decreasing the within row spacing increased the forage and biological yields. Considering the stress tolerance (STI), geometric mean productivity (GMP) and grain yiled, KGS23 promising line which had higher grain yield in all irrigation regimes was identified as tolerant line with high grain yield.

To evaluate the growth duration and seed yield of two different Guar ecotypes in response to planting time and plant density, a field experiment was conducted in 2016 growing season at the research field of Tarbiat Modares University, Iran. Experimantal factors were arranged as split plot-factorial in a randomized complete block design with three replications. The experimental factors included four planting dates (21 May, 4 June, 21 June and 5 July) assigned to main plots, and factorial combination of three plant densities (130, 200 and 400 thousand plants.ha-1) and two Guar ecotypes (Pakistani and Indian) as sub-plots. The results showed that maximum seed yield (3004.8 kg.ha-1) was obtained from 21 May sowing date and plant density of 130 thousand plants ha-1, while in 4 June sowing date, the highest seed yield was harvested from plant density of 200 thousand plants.ha-1 (1834.4 kg.ha-1). There was significant difference for grain yiled between ecotypes in 21 May and 5 June sowing dates. Pakistani ecotype produced highest highest seed yield (2706.1 kg.ha-1) in 21 May sowing date. In the second sowing date (4 June), the Pakistani ecotype produced 32.1% grain yield more than the Indian ecotype. Pakistani ecotype was superior for seed endosperm percentage (40.5%) as compared to the Indian ecotype (38.8%). In conclusion, sowing of Pakistani ecotype on 21 May with plant density of 130 thousand plants.ha-1 had higher seed yield, longer growing duration, taller plant height, higher 1000-seed weight, higher pod number per square meter, dry matter and harvest index. Therefore, it could be suitable for climatic conditions similar to Karaj in Iran.

Identification of adapted genotypes with high grain yield is the most important goal in durum wheat breeding programs. To study adaptation and grain yield stability of durum wheat genotypes, 18 durum wheat promising lines with two commercial durum and bread wheat cultivars were used. The durum wheat genotypes were evaluated in four locations; Isfahan, Karaj, Kermanshah and Neishabour in temperate agro-climate zone of Iran in 2013-14 and 2014-15 cropping cycles. The experiments were conducted using ranodomized complete block design with three replications. Combined analyses of variance were performed for grain yield. The genotype and genotype × year × location effects were significant. Therefore, for more precise evaluation of genotype by environment interactions and grain yield stability, parametric and non-parametric analysis methods such as AMMI, rank and standadard deveiation (SD) of rank, coefficient of environmental variation was employed. Results of all three stability analysis methods showed that genotypes no. 3 and no. 4 with high grain yield (8650 and 8699 kg.ha-1, respectively) and low G × E interaction were adapted with grain yield stability durum wheat genotypes. These superior durum wheat genotypes were identified for being released as new commercial durum wheat cultivars for temperate agro-climatic zone of Iran.

To compare the replacement intercropping patterns of fennel (Foeniculum vulgare Mill.) and faba bean (Vicia faba L.) at different levels of vermicompost, a field experiment was conducted as factorial arrangement in randomized complete block design with three replications at the research field of the Faculty of Agriculture, Urmia University, Iran, in growing season of 2018. Experimental treatments included six planting ratios: sole cropping of fennel and faba bean, one row of fennel + one row of faba bean, two rows fennel + two rows faba bean, three rows faba bean + two rows fennel, four rows faba bean + two rows fennel, and two levels of vermicompost: 0 and 10 t.ha-1. The results showed that the highest seed yield (2568.33 kg.ha-1) of fennel was obtained in the sole cropping and the lowest seed yield (1396.67 kg.ha-1) was belonged to the one row of fennel + one row of faba bean, respectively. Essential oil and oil content (%) of fennel were higher in all intercropping system than in sole cropping. Application of vermicompost could increase seed yield, essential oil content, essential oil yield, oil conten (%) and fennel oil yield by 20.48%, 14.52%, 32.72%, 11.12% and 29.37,  in comparison with control (no application of vermicompost), respectively. The highest amount of E-anethole of essential oil (79.9%) and oleic fatty acid (83.1%) of fennel were obtained from three rows of faba bean + two rows of fennel with vermicompost consumption. The highest land equivalent ratio (1.42) was obtained in the  three rows faba bean + two rows fennel intercropping system fertilized with vermicompost, indicating that intercropping improved land use efficiency by 42%, when compared to sole cropping. This cropping system was identified more suitable for increasing land use efficiency particularly in the medicinal plants production systems.

One of the main problems for rice production is the large difference between farmers' actual yields and attainable yields. Therefore, it is important to identify the limiting factors on yield and yield gap. In this research, all performed management practices from seedbed preparation to harvesting in 228 paddy fields of local rice cultivars in the east, central and west parts of Mazandaran province, Iran were surveyed through field monitoring in 2015 and 2016. The results showed that the variables of certified seed, seedling age, and potassium application, nitrogen application after flowering, harvest time and pest problem were introduced into the comparative performance analysis (CPA) equation. The actual yield of the field and the calculated yield potential were estimated 4456 and 6642 kg.ha-1, respectively, hence the yield gap was estimated 2186 kg.ha-1. In the boundary line analysis (BLA), by fitting one line on the upper edge of the data, it was determined that the response function as a dependent variable to independent variables on seed rate, transplanting date, planting density, nitrogen application. Moreover, basal nitrogen application, nitrogen application in vegetative and after flowering stages had a positive piecewise function. The seedling age variable, phosphorus and potassium application and the number of seedling per hill followed a negative piecewise function. However,, four variables including the lodging, pests, diseases and weeds problems followed a linear function. According to BLA, the average yield was 5755 kg.ha-1 with a yield gap of 1207 kg.ha-1. An average relative yield and relative yield gap were estimated 79.8% and 20.90%, respectively. Given that the calculated yield potential in this analysis in three regions was obtained from the actual data of each field, it can be concluded that the yield potential is dependent on the region and is attainable.

Rhizoctonia root rot disease is considered as one of the important diseases in sugar beet. Using resistant cultivars decreses production costs, especially application of fungicides and increases the efficiency in controlling of root rot disease. Therefore, growing of resistant cultivars is considered the best approach for disease control. To achieve this goal and to determine yield potential of new sugar beet hybrids resistant to Rhizoctonia root rot disease, 92 hybrids as well as susceptible and resistant cultivars were evaluated in two experiments in research field of Ekbatan station of Hamedan, Iran in 2016. Considering the experimental results and with respect to the average effect of pollinators and single crosses, 20 hybrids were selected and evaluated in Karaj, Hamedan, Ghazvin, Torbate Jam and Shiraz regions in 2017. Evaluation of hybrids in term of resistance to rhizoctonia was simultaneously performed under micro-plot conditions in Hamedan. In both years (2015 and 2016), the experiment was conducted in randomized complete block design with six replications. The results of resistance evaluation under micro-plot conditions reavealed that five hybrids consisting; 9, 13, 16, 4 and 18 were more resistant than cv. Ekbatan for resistance to rhizoctonia root rot disease. Yield potential evaluation in different locations showed that new hybrids had desirable level of yield potential and most of them had no significant difference with cv. Ekbatan.Considering the results of resistance to rhizochtonia disease and yield potential evaluation, three hybrids no. 4 (SC(P.395*P.90)*P.165), no. 9 (SC(P.395*P.90)*P.121) and no. 16 (SC(P.395*P.23)*P.165) that were more resistance with higher yield potential in comparison with cv. Ekbatan were identified as promising hybrids for being evaluated in Value for Cultivation and Use (VCU) test.