نشریه به زراعی نهال و بذر
سال بیست و نهم شماره 4 (1392)

Sunn pest (Eurigaster integriceps Put.) is one of the major pests of wheat and barley in Iran. This pest attacks wheat and barley fields and causes significant quantitative and quality damages in grains. This research was conducted to investigate the effect of different percents of grain damage caused by sunn pest on baking quality of wheat. Grains of ten bread wheat cultivars were sampled from some sunn pest prone Provinces of Iran. All damaged grains were separated from healthy grains، and then divided into 8 sub-samples with 0 to 5 percent of damaged grain including: 0%، 0. 5%، 1%، 1. 5%، 2%، 3%، 4% and 5%. These sub-samples were replicated four times. The first two replications were sent to cereal chemistry laboratory of Seed and Plant Improvement Institute and the second two replications were sent to chemistry laboratory of Cereal Research Center to measure the bread making quality indices. Two replications of 10% damaged grains were also prepared for each cultivars. Results showed that there are significant differences among cultivars for quality indices. There was not significant differences among percents of grain damage up to 5%، but in grains damaged more than 5% to 10%، there was severe reduction in bread making quality indices، especially in protein content (%) and wet gluten (%)، Zeleny sedimentaion and SDS values. In samples with more than 5% damaged grains the rate of reduction of bread making quality indices showed significant relationship with bread making quality of bread wheat cultivars.

To determine the effect of seeding rate and nitrogen fertilizer on seed yield and its components for oilseed rape a field experiment was carried-out in Agricultural Research Station of Islamabad-e-Gharb in two cropping seasons (2007-08 and 2008-09). A factorial arrangement using randomized complete block design with 4 replications was used. Experimential factors were seeding rate at 4 levels; 4، 6، 8 and 10 kg ha-1 and five nitrogen fertilizer rates; 0، 30، 60، 90 and 120 kg ha-1 from urea source. Results showed that seed yield was affected by increasing seeding rate as the seed yield in highest and lowest seeding rates were 5391 and 4041 kg ha-1، respectively. Increasing seeding rate reduced branch plant-1 and pod plant-1، but increased plant height. Results also showed that increasing nitrogen increased seed yield as the highest level of nitrogen had the highest seed yield with 5392 kg ha-1 and the lowest seed yield with 4257 kg ha-1 belonged to the lowest nitrogen level. Seed yield، 1000 seed weight، plant height and pod plant-1 increased as application of nitrogen fertilizer increased.

Cold stress is the important factor that reduces yield of fall planting potatoes in sub-tropical regions of southern Iran. Therefore، to assess the possibility of reducing damage of cold stress a field experiment was conducted in 2010-2011 in Agricultural Research Center of Jiroft in southern part of Iran. Experimental design was strip factorial arrangement in randomized complete block design with three replications. Experimental treatments included planting dates (11 September، 21 September، 01 October and 11 October)، and potato cultivars (Santé، Ramose، Oceania and Arinda)، and anti-freeze (application and no application). During growing season physiological traits including leaf area index، tuber dry matter، proline accumulation and tuber yield were measured and recorded. Results showed that the effects of planting date، genotypes and anti-freeze and their interactions were significant (p < 0. 01) on physiological traits. Maximum tuber dry matter (18%) was observed in third planting date in Santé with anti-freeze application. Anti-freeze increased dry matter by 1. 2%. The highest accumulation of proline was observed in third planting date in Ramose and application of anti-freeze which increased proline accumulation by 19. 5%. Maximum LAI (4. 47) was also observed in first planting date in Arinda and anti-freeze application which was 16. 7% greater than non-anti-freeze treatment. The highest tuber yield (26. 7 t ha-1) was obtained for Sante with application of anti-freeze in the second planting date، and the lowest tuber yield (6. 2 t ha-1) for Ramose in first planting date and no application of anti-freeze. In conclusion the risk of chilling and freezing stress damages can be reduced with second planting date، Santé cultivar and anti-freeze application.

To study the trend of changes in grain yield، growth indices، stem soluble carbohydrates and canopy temperature in 15 spring bread wheat cultivars released between 1951-2008 in Iran، a field experiment was carried out using randomized complete block design with three replications in Research Field Station of Seed and Plant Improvement Institute in Karaj، Iran، in 2011-2012 cropping cycle. Results showed that grain yield has increased by 35 kg ha-1 year-1 from 1951 to 2008. The highest grain yield (5. 38 kg ha-1) belonged to Parsi a recently released cultivar and the lowest grain yield (2. 81 kg ha-1) obtained from Sholeh an old cultivar. Analysis of variance showed that the growth indices; crop growth rate (CGR)، relative growth rate (RGR) and leaf area index (LAI) were significantly different (P ≤ 0. 01) among spring bread wheat cultivars. The modern cultivars research to maximum LAI earlier than older cultivars. The leaf area duration (LAD) was also longer in modern cultivars. Most of cultivars reserved carbohydrates in pedunde and penultimate internode in 14 days after anthesis and then remobilized it to developing grains. The quantity of reserved stem soluble carbohydrates was greater in penultimate internode. Canopy temperature at anthesis stage was cooler in modern cultivars.

Sweet corn has a short life cycle and its sequentinol planting is possible and can be grown in rotation with cucumber in greenhouses of Jiroft in Iran as a profitable crop. A split-plot arrangement in randomized complete block design with three replications was carried out in two growing seasons of 2008-09 and 2009-10 in the greenhouses of Agricultural Research Station of Jiroft to determine the most appropriate sowing date and cultivar of sweet corn. Sowing date at three levels 1st، 11th and 21st August were assigned in main plots and five hybrids: Chase، Temptation، Basin، Challenger and Obsession were randomized in sub-plots. The sowing and harvest were conducted three times per year. First under open air inside the greenhouse and the others inside the roofed greenhouse. In the second sequential planting which was under plastic roof of the greenhouse، the main plots were planting date (14th October، 31st October and 12th November) and the sub-plots were the same hybrids. In the third sequential planting the main plots were planting date (14th January، 30th January and 21st February) and the sub-plots were the same sweet corn hybrids. In the third sequential planting، young sweet corn plants spent part of their growing periods under open air by removing the plastics. Results showed that the highest fresh ear yield (24. 06 t ha-1) was obtained from the planting date of 21st August. In the second suquential planting the highest and lowest ear yields were obtained from planting dates of 14th October and 12th November (24. 79 and 17. 69 t ha-1، respectively). Also، the highest ear yield was produced by cultivar Challenger (22. 13 t ha-1). In the third sequential planting، the highest ear yield was obtained from planting dates of 14th January (18. 5 t ha-1) and the highest yield for hybrids from Obsession (18. 11 t ha-1). In conlusion، 21st August and all hybrids for the first planting، 14th October and Basin (with 21. 39 t ha-1 forage yield) and Obsession (with 22. 74 t ha-1 forage yield which is important in winter) for the second sequential planting and 14th and 30th January and Obsession and Temptation hybrids for third sequential planting are recommended.

This experiment was conducted in 2009-10 and 2010-11 cropping cycles to evaluate drought tolerance of eighteen durum wheat genotypes using randomized complete block design with four replications under two moisture regimes (supplemental irrigation and rainfed) at Gachsaran Dryland Agricultural Research Station، Ghachsaran، Iran. Combined analysis of variance indicated that genotypes had significant differences for grain yield in supplemental irrigation (YP) and rainfed (YS) conditions. Considering YP، YS and drought tolerance indices genotype number 6 (GA//2*CHEN/ALTER84) with CIMMYT origin was identified as the most tolerant genotypes. GMP، MP، STI، K1STI and K2STI indices had positive and significant correlation with YP، YS and other indices except SSI، TOL، GOL and YSI. Therefore، these indices can be used for identification of tolerant durum genotypes. Results of principle component analysis explained 99% of total variation by the first component. The first and second components were identified as yield potential and stress tolerance components، respectively.

To evaluate the effect of planting date and seeding density on agronomic traits، grain yield and harvest index of three barley cultivars، a field experiment was conducted as split plot factorial arrangement in randomized complete block design with three replications at Agricultural and Natural Resources Research Center of Yazd Provience، Yazd، Iran، in 2009-2011 Cropping cycles. Main plots included three planting dates (03 November، 20 November and 06 December) and Sub-plots consisted of cultivars (Nosrat، Yousof and Fajr 30) and seeding density (350، 400 and 450 seed m-2) as factorial arrangement. During the growing seasons different traits including days to tillering، days to stem elongation، days to spike emergence، days to physiological maturity، plant height، spike length، grain yield and harvest index were measured and recorded. Combined analysis of variance indicated that the effect of planting date on plant height and grain yield was significant. Significant differences in spike length، plant height and grain yield was bserved among cultivars. However، the effect of seeding density on studied traits was not significant. The highest grain yield (6224. 7 kg ha-1) obtained in planting date of 03 November، Nosrat cultivar (5868. 3 kg ha-1) and density of 400 seed m-2 (5538. 1 kg ha-1 without significant difference with other seeding density). The lowest grain yield belonged to planting date of 06 December (4368. 6 kg ha-1)، Yousof cultivar (4930. 5 kg ha-1) and seeding density of 350 seed m-2 (5341. 8 kg ha-1 without significant difference with other seeding density). Nosrat cultivar with seeding density of 400 seed m-2 in planting date of 03 November had the highest grain yield (7260. 7 kg ha-1).

A field experiment was conducted at Indian Agricultural Research Institute، New Delhi، India، during rainy seasons of 2009 and 2010 to evaluate three sweet sorghum genotypes (‘RSSV 9’، ‘SSV 84’ and hybrid ‘CSH 22 SS’) under four nitrogen levels (0، 50، 100 and 150 kg N ha–1) for productivity، and bio-ethanol production. Combined analysis of variance indicated that effects of nitrogen and genotype were significant (P<0. 01) on plant height، leaf area index (LAI)، dry matter yield، grain yield، fodder yield، juice yield، brix (%)، fermentable sugar yield and bio-ethanol. The highest values of these traits were obtained by application of 150 kg N ha-1. Among sweet sorghum genotypes hybrid “CSH 22 SS” produced the highest of fresh matter yield، total dry matter yield، grain yield and fodder yield with 98. 71، 24. 64، 2. 48، 16. 84 t ha-1، respectively. It also had the highest juice yield، fermentable sugar yield and ethanol yield with 49. 99، 4. 59 and 2. 61 Kl ha-1. The superiority of hybrid “CSH 22 SS” for growth parameters; plant height، LAI compared to other genotypes was also significant. Genotypes × nitrogen interaction effect on all evaluated traits، except brix (%)، was significant. Hybrid ‘CSH 22 SS’ responded significantly up to 150 kg N ha-1، while other varieties responded to N application only up to 100 kg N ha-1. It is concluded that application of 150 kg N ha-1 and hybrid “CSH 22 SS” can be recommended for enhancing of growth، bio-ethanol، grain and fodder yields of sweet sorghum in target region.

Optimum plant density and suitable size of mother bulb are important factors for onion seed production. To study the effect of bulb size and plant density on seed production of Neishabour white onion variety، this experiment was carried out in Agricultural Research Station of Neishabour in Iran. Factorial arrangement in randomized complete block design with three replications was used. Experimental factors induded three different bulb diameters (3-5، 5. 1-7، and 7. 1-9 centimeters) and three different plant spacing (10، 20 and 30 centimeters). Seed yield increased to 2011 kg ha-1 by increasing bulbs diameters (7. 1 to 9 centimeters) and decreasing the plant spacing (10 centimeters). Seed germination rate (%) and seed germination velocity increased with larger bulbs and wider plant spacing.

To study the effect of cover crops on weeds dry matter and grain yield of wheat cv. Chamran، a field experiment was carried out at the Safiabad Agricultural Research Center، Dezful، Iran، in 2009-2010 cropping season. The experimental design was randomized complete block with four replications. Cover crops included، mung bean، clover and fallow that were grown and practiced and returned in soil before wheat was planted. Results showed that the effect of cover crops was significant (P ≤ 0. 01) on weeds dry matter in three stages of wheat; stem elongation، heading and physiological maturity. Cover crops also had significant (P. ≤ 0. 01) effect on spike m-2، grain spike-1 and grain yield of wheat cv. Chamran. Results also indicated that mung bean controlled weeds more effectively and increased spike m-2 (by 148 spike m-2)، grain spike-1 (by 8 grain spike-1) and grain yield (by 1. 341 t ha-1) as compared with fallow treatment. Therefore، cover crops can be considered as an effective agronomic management practice for weeds control and increasing grain yield of wheat cv. Chamran in north Khuzestan.

Factorial and split-plot designs are two statistical procedures used to conduct agricultural field experiments. Both designs are used frequently to quantify the main and interaction effects of two or more factors. However، split-plot design is recommended for specific situations depending on major and minor goals of the study، characteristics of the factors، and precision of statistical testing mentioned in this note. In field experiments، when date of planting is one of the factors، split-plot design should be used. The reasons are explained in detail in the note. Using a factorial instead of a split-plot design when date of planting is a factor would result in data confounded with other external environmental variation and therefore the results obtained would not be statistically valid.