نشریه بوم شناسی گیاهان زراعی
سال هشتم شماره 2 (پیاپی 27، تابستان 1391)

The effect of different concentrations of potassium humate organic matter was investigated on yield and yield components of five potato varieties in spring planting date of 5th May in Ardabil region, northwest Iran. Experiment was carried out as factorial based on a randomized complete block design with three replications during 2010 and 2011 growing seasons. Potassium humate was applied at three levels (0, 250 and 300 mL.ha-1 in 300 liter water) and the studied potato varieties included Agria, Savalan, Kaizer, Markiz and Lota. Traits including number of stems, number and weight of tubers per plant, and tuber yield were measured during growing season and after harvesting. Results revealed significant effect of potassium humate, variety and interaction of potassium humate and variety on the studied traits. Savalan and Agria had the highest number of main stems per plant and the lowest number of that was observed in Lota. Number of tubers per plant was higher for Savalan than other studied cultivars. The highest number of tubers per plant was obtained with 250 mL.ha-1 potassium humate application. Savalan also produced the highest tuber weight per plant. The highest tuber weight per plant was obtained when 250 mL.ha-1 potassium humate was applied. Savalan produced the highest total tuber yield when 250 mL.ha-1 potassium humate was applied. Based on the results, Savalan, Kaizer and Markiz were recognized as high product and stable varieties, whereas Agria and Lota were unstable ones with lower yield.

In order to evaluate the economic advantage of alfalfa intercropping compared to alfalfa sole cropping, an experiment was conducted as split plot based on a randomized complete block design with three replication in karaj in Seed and Plant Improvement Institute farm, Karaj during 2007 and 2008. Economic method was partial budgeting technique. Economic results showed that alfalfa mixed cultivation with festuca (15: 3.75 kg/ha) selected as good treatment, because substitution of this treatment by other treatments was non-economic. Net profit of this treatment estimated up to 43.8 million rial/ha that was more than other treatments. Breakeven of point for income in alfalfa mixed cultivation with festuca (5: 3.75 kg/ha) to alfalfa mixed cultivation with grasses (5:11.25 kg/ha)) and the treatment of alfalfa mixed cultivation with grasses (10:7.5 kg/ha) was estimated 63464 and 61623 (000 rials), respectively. Mixed cultivation of alfalfa (%75) and dactylis (%25) resulted in the highest mean LER (2.1) in the experimental years.

This research was performed to evaluate the effect of potassium humate on potato seed germination rate in the greenhouse, tuber yield and yield components in the field and estimation of heterosis rate and dominance degree in true potato seed hybrids during three years (2008-2010). In this experiment, 3500 true seeds of potato hybrid variety HPS-II/67 were planted after treated with potassium humate for 6, 12, 18 and 24 hours in the planting bed of Biolan peat mass in the greenhouse and direct seed planting was considered as a control. Attributes such as time to seed germination, seed germination percentage and days to germination were recorded in the greenhouse. 540 potato seedlings were transferred to the field at 4-5 leaf stages. The experimental design was a completely randomized block design with three replications. After harvest, number and weight of tubers per plant, tuber average size and marketable tuber yield were counted and measured and 300 hybrids were selected. The selected hybrids and Agria cultivar (control) were planted at Agricultural and Natural Resources Research Station of Ardabil during 2010. The results showed that differences between different treatments of potassium humate were significant for tuber number and weight per plant, tuber average size and marketable tuber yield. The maximum seed germination percentage, tuber number and weight per plant and marketable tuber yield were obtained for 6, 12 and 18 hours treatments of potassium humate. Potassium humate increased germination by 41% and 1.2 kg per m2 marketable tuber yield. Mean tuber yield per plant was 550 g in control and 613.08 g in hybrids. Tuber yield per plant for hybrids had 23.67% over dominance, 6.33% complete dominance, 64% reduction dominance and 6.0% without dominance. In this experiment, about 50.33% of hybrids (151 hybrids) had high tuber yield per plant than their control. Heterosis for tuber yield per plant was achieved 50.33%. Finally, 50 hybrids were selected regarding to tuber yield, tuber uniformity, shallow eye depth, short stolon and yellow flesh and skin color, heterosis rate and dominance degree.

To investigate the effect of foliar application of zinc on yield production and seed quality of wheat under water deficit, an experiment was conducted as split factorial based on a randomized complete block design with three replications during 2009 and 2010 growing seasons. The main plot consisted of different water conditions (complete irrigation, halted irrigation after pollination, and after grain milk stage) and sub-plots comprised three wheat genotypes including Mahdavi, Shiraz and Pishtaz and three different concentrations of zinc including 0, 2.5 and 5 mg.kg-1. The results indicated that increasing stress intensity caused decreased grain yield, total dry matter and harvest index, but seed protein increased. Although, by increase water deficit, grain yield was reduced in all cultivars. Pishtaz showed the maximum grain yield (6107 kg/ha) when irrigation halted at pollination phase. However, all varieties, especially Mahdavi, produced higher yield at complete irrigation condition. Zinc sulfate application had a positive and significant effect on the most studied traits, so that application of 2.5 mg/kg zinc sulfate at complete irrigation treatment increased grain yield up to 27%. Besides, zinc concentration of seeds increased as zinc sulfate was applied.

Effects of different tillage methods was evaluated on emergence percentage, seed yield and yield components (number of pods per plant, number of seeds per pod, 1000 seeds weight, oil content, oil yield and seed yield) of canola cv. Hayola 401. Experiment was carried out as a randomized complete block design with three replications in Soghan region, Orzooyeh, Kerman province of Iran during 2011-2012. Treatments comprised chisel plow with two times harrowing disk, cultivator with two times harrowing disk, two times harrowing disk, one time harrowing disk, no-tillage and control (conventional tillage including moldboard plow with two times harrowing disk). Results showed that minimum tillage (two times harrowing disk) resulted in the maximum emergence percentage (85.2%) as compared to the other treatments. The maximum seed and oil yield was obtained using chisel plowing as first tillage and two times harrowing disk as second tillage. Minimum tillage system containing operation of chisel plow as the first tillage and two times harrowing disk as the second tillage was recognized as the most suitable tillage method for canola cultivation.

This research was performed in order to investigate the effect of salicylic acid and sodium nitroprusside on growth and essential elements content in spring canola under nickel stress in laboratory of Science and Research Branch, Islamic Azad University of Tehran. The interactive effects of nickel, salicylic acid (SA) and sodium nitroprusside (SNP) as a donor of nitric oxide (NO) were examined on canola (Brassica napus L. cv. PF) growth. 21-day old canola seedlings (cv. PF) were exposed to different concentrations of NiCl2, 6H2O (0, 0.5 mM), SA (0, 0.2 mM) and SNP (0, 0.2 mM) for 10 days. Nickel toxicity symptoms such as chlorosis and necrosis were observed on leaves of Ni-treated seedlings. Treatment with Ni resulted in a decrease in fresh and dry weight of roots and shoots. Mineral elements content (Mg, Fe, Ca, P, K) extremely decreased in roots and shoots of Ni-stressed canola seedlings, while the content of N in these seedlings increased in roots and decreased in shoots. Ni was more accumulated in roots than in shoots. In Ni-stressed seedlings, application of SA or NO, especially SA+NO, improved the growth and decreased the toxicity symptoms as compared to Ni-treated seedlings. SA or NO, especially both together, considerably reduced root-to-shoot translocation of Ni and increased the content of mineral elements in roots and shoots of Ni-stressed seedlings. These results showed that SA or NO and in particular their combination, markedly reduced the toxic effects of nickel on canola seedlings by sequestration of Ni in roots and amelioration of mineral nutrition.

In order to investigate the effect of planting date on some morphological and phenological traits of six medium maturity promising corn hybrids in the north of Khuzestan, an experiment was conducted as a split plot based on a randomized complete block design with four replications at Safi-Abad Agricultural and Natural Resources Research Center of Khuzestan in 2008. Main plots included six planting dates (June 30th, July 7th, 14th, 21st and 28th and August 4th) and sub plots consisted of six hybrids of corn and the hybrid SC704 was considered as a control. Results showed that both vegetative growth period, growing degree-day (GDD) and total growth were influenced by planting date and variety. The highest GDD was obtained at first planting date. Among different planting dates, maximum plant height was obtained on August 4 with 203 cm. Among different hybrids, maximum plant height related to SC 704 with 190 cm. Both ear length and first ear height had an increasing trend toward the late planting dates. By considering the corn-wheat rotation and harvesting problems of corn cultivation in summer Khuzestan province, planting date of July 28 is suggested for warm climates like Khouzestan.

Fusarium wilt causes cosiderable yield loss in most tomato-growing regions around the world. The best way to control this disease is using tomato resistant cultivars. Molecular markers linked to resistance gene would be useful for tomato improvement programs. In this study, a cleaved amplified polymorphic sequence (CAPS) marker (TAO1902) was used to identify tomato cultivars possessing I-2 gene, which confers resistance to Fusarium oxysporum f. sp. lycopersici race 2. DNA was extracted using CTAB method from 27 hybrids and commercial tomato varieties. To evaluate existence of I-2 gene in tomato cultivars, PCR-RFLP was down using RsaI and FokI restriction enzymes. An RsaI-digested fragment of 500 bp and two restriction fragments of 390 and 410 bp for FokI digestion of TAO1902 were revealed in the resistant varieties. Results showed that 14 out of 27 tomato hybrids and cultivars were homozygous resistant and the other 13 hybrids were susceptible to fusarium wilt. Pathogenicity test showed that there were no symptoms in resistance gene I-2 amplifing tomato varieties. However, tomato varieties with no resistance band produced disease symptoms with different disease intensities. Results showed that 7 out of 27 tomato cultivars and hybrids, and 7 hybrids were resistant to F. oxysporum f. sp. lycopersici race 2 and so, these cultivars and hybrids are recommended in regions that race 2 of the fungus is dominant.