نشریه بوم شناسی گیاهان زراعی
سال هشتم شماره 1 (پیاپی 26، بهار 1391)

Effects of planting date, depth and distance on growth and yield of saffron were studied in Maku environmental condition. The experiment was factorial based on a complete randomized block design with two planting dates (16th and 29th September), two planting depths (20 and 25 cm) and two plant distances (20, 25 cm) with tree replications during 2008-2010. Results showed that number of leaves, fresh and dry weight of leaves, wet and dry weight of flowers, fresh and dry weight of stigma, and length of stigma and leaf area were affected by treatments. The indices of plant growth and yield components such as number of leaves, stigma length, fresh and dry weight of leaf, flower, stigma and leaf area were increased in the first date of planting (16th September). The plant distance has also affected plant growth and yield production. The highest yield was obtained in less plant distance and low planting depth treatment.

Effects of chemical and organic fertilizers combinations on yield, yield components, seed oil and protein percentage of two canola cultivars were studied. The experiment was carried out as factorial based on a randomized complete block design with three replications in Agricultural and Natural Resources Research Center of Azerbaijan-e-Sharqi province of Iran in 2010. The first factor comprised seven levels of organic and chemical fertilizers and their combinations including: non cattle manure and non urea (control), 100% cattle manure (organic), 80% cattle manure and 20% urea (combined), 60% cattle manure and 40% urea (combined), 40% cattle manure and 60% urea (combined), 20% cattle manure and 80% urea (combined) and 100% urea (chemical) and the second factor was two canola cultivars (Okapi and Modena). The results showed that the highest yield, yield components, oil and protein percentages were obtained from a combination treatment, application of 20% cattle manure along with 80% urea (96 kg/ha), that was differed significantly from other chemical treatments for seed yield and number of seeds per pod. Therefore, application of this treatment could be recommended because it leading to a higher yield with lower chemical fertilizer application. Besides, variety okapi was superior to Modena based on the measured characteristics.

In order to study the drought tolerance of new forage maize hybrids, an experiment was conducted under stress and non- stress conditions in experimental field of Seed and Plant Improvement Institute in Karaj 2009. The experiment was carried out as split-plot based on a randomized complete block design (CRBD) with three replications. The main factor consisted of three levels of irrigation regimes (irrigation after 70, 100 and 130 mm cumulative evaporation from evaporation pan class A) and 14 corn hybrids were planted in sub-plots. Mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), tolerance (TOL), yield index (YI), yield stability index (YSI), stress susceptibility index (SSI) were evaluated based on forage yield under normal and stress conditions. Analysis of variance for drought tolerance indices and forage yield showed that only mean productivity in normal and mild stress conditions, and geometric mean productivity together with yield index in non-stress and severe stress conditions were significant. The results of correlation analysis between drought tolerance indices and yield showed that GMP and MP were the best indices for determination of drought tolerant hybrids under normal, mild and sever stresses conditions. Regarding to various drought tolerant indices, hybrids K 47/3-1-2-7-1-1-1 × MO17 and KLM 76004/3-2-1-1-1-1-1-1 × K3544/1 were identified as drought tolerant hybrids.

Tomato fruits have some antioxidants like carotenoids, lycopene, vitamin C, vitamin E and phenolic compounds and play an important role in human health. Since the time between fruit harvest and consumption may last several weeks, biochemical changes during the storage period may affect the nutritional value of fruit and these changes may vary in different cultivars. This experiment was carried out to study qualitative characteristics of two tomato cultivars (Chef and Sunseed) from harvest to consumption.
Tomato fruit was harvested at the mature green stage and was stored at 16°C and 80% relative humidity for 35 days. The quality factors including firmness, pH, total soluble solids, titratable acidity, TSS/TA, weight loss, chlorophyll and carotenoid content and decay percentage was measured in every seven days during this period. The results showed that firmness, weight loss and chlorophyll content were decreased and TSS, TSS/TA, Vitamin C, carotenoid content and decay percentage increased during postharvest storage in both cultivars. Vitamin C was higher for Chef and weight loss and carotenoid were higher for Sunseed. The results of this study could be applicable for human subject feeding studies that focus on nutritional values of tomato.

In order to study the effect of different tillage methods on safflower yield, an experiment was conducted as randomized complete block design (RCBD) with three replications at Khosroshahr Research Station of Azarbaijann – e – Sharqi province of Iran in 2004 and 2005. Treatments comprised of chisel plow in depth of 15 - 20 cm, moldboard plow in depth of 15 - 20 cm, mould board plow in depth of 25 - 30 cm and a check (no tillage). Grain yield and yield components were measured for evaluating and analysis. The results showed that the effect of year was not significant on yield and its components. The mean yield was 3898 kg/ha in the first year and 3216 kg/ha in the second one. The interaction effects of year and tillage methods were significant at 5% level of probability for yield. The highest yield (4501 kg/ha) was observed in no tillage treatment in the first year and chisel plow treatment caused the lowest yield (2696 kg/ha) in the second year. Effect of different tillage methods on safflower grain yield and yield components was not significant. The highest mean yield obtained for no tillage method (3599 kg/ha) and the lowest was related to chisel plow (3307 kg/ha). Based on the results, as safflower yield was not affected by tillage methods after wheat cultivation, therefore safflower can be cultivated without plowing due to no tillage advantages in cultural management.

Alfalfa and sainfon mixed cropping has a prolonged history in Zanjan province of Iran. In order to evaluate the effect of this approach on forage yield and alfalfa weevil (Hypera postica) population, this research was carried out as split plot based on a randomized complete block design with four replications at Kheir-Abad Research Station of Zanjan Agricultural Research Center in 2003-2005. Spraying and non spraying were considered as levels of the main factor and five ratios of mixed crops (25%, 50%, 75%, and individual crop) were allocated to sub-plots. Combined analysis of variance were made for wet and dry yield and number of weevil larvae population. Results showed that mixed cropping at a ratio of 50% of each crop was the best ratio for mixed cropping, because of its high yield (30.62 t/ha) from sprayed plots, and non-significant yield decrease in unsprayed plots (29.42 t/ha).

This experiment was carried out in order to investigate the effect of plant density on yield of two soybean cultivars as factorial based on a randomized complete block design with three replications at Khazarabad, Sari region in 2007. Factors were plant distance at three levels (5, 10 and 15 cm), row distance at two levels (40 and 50 cm) and two cultivars (Sahar and Sahel). Results showed that the effect of plant distance, row distance, cultivars, interaction of plant distance and cultivar, interaction of plant distance and row distance and triple interaction of plant distance, row distance and cultivar was significant on seed, oil and protein yields. The maximum yield (5681 kg) was observed for interaction of plant distance of 5 cm and row distance of 40 cm. The most grain yield (6569 kg) was produced at plant distance of 5 cm and row distance of 40 cm for Sahel cultivar and the least grain yield (4796 kg.ha-1) was produced by plant distance of 15 cm and row distance of 50 cm for Sahel cultivar. However, the most oil percentage (54.57%) were obtained at plant distance of 15 cm and row distance of 50 cm in Sahel cultivar and it was 57.54% for Sahar cultivar at plant density of 5×50 cm. Therefore, the highest grain yield was produced for Sahel cultivar at plant density of 5×40 cm and for Sahel cultivar at density of 15×40 cm.
In conclusion, row and plant distances and the type of cultivar had significant effect on yield and yield components of soybean at Sari condition, so that each cultivar produced higher yield in a specified density.

Effect of different water deficit treatments and nitrogen levels was studied on yield and yield components of rice (Oryza sativa L.) var. Tarom Hashemi at Neka region, Mazandaran province of Iran in 2009. The experiment was carried out as strip split plot based on a completely randomized block design with four replications. The main factor was water deficit treatments consisted of waterlogging (control); and water deficit at tillering, flowering and seed filling stages for 15 days, and the second factor included four nitrogen fertilizer levels (0, 50, 100 and 150 kg/ha) from urea source. Analysis of variance showed that the effect of water deficit treatments and nitrogen fertilizer levels was significant on yield, biological
yield, stem diameter and number of tillers. Increased levels of nitrogen fertilizer had an increasing effects on all the studied traits, except harvest index. Water withhold at tillering stage affected plant height, number of tillers, stem diameter, biological yield and yield, negatively. Waterlogging with 150 kg/ha nitrogen fertilizer application increased grain yield and was the most effective treatment. Despite water is the main limitation for rice production in many areas, the highest yield was obtained at waterlogging treatment.