CROP PRODUCTION IN ENVIRONMENTAL STRESS
Year:2011 | Volume:2 | Issue:3-4 (SERIAL 5)|Papers Count:7

In order to study of compatibility of three sunflower hybrids at interference with different densities and emergence times of redroot pigweed (Amaranthus retroflexus L.), two field experiments were carried out during 2005 and 2006. Factorial experiments were established on Randomized Complete Block Design with three replications. Three factors included three different weed densities (8.3, 25 and 41.7 plants m-2), three relative times of weed emergence (emerged with sunflower; 15 and 30 days after sunflower emergence) and three different sunflower cultivars (Azarghol, Hysun 33 and Allstar RM). Three weedfree sunflower cultivars as controls were seeded. Results indicated that leaf appearance rate and phyllochrone in sunflower from fifth leaf to later in treatments of weed emerging with sunflower at densities of 25 and 41.7 plants m-2 in Hysun and Allstar hybrids decreased. Time to anthodium appearance in treatments of full season interference of 25 and 41.7 weeds m-2 increased up to 15% and 16% in Hysun, and 38% and 47% in Allstar hybrids, respectively, compared with control. In Hysun and Allstar, weed emergence time was more effective than weed density on time to flowering of sunflower. In Azarghol, only third level of weed density could decrease stem height of sunflower, and this kind of effect was removed from 75 days after sunflower emergence. Improvement of sunflower hybrids with high stem height will increase that's competitive power with redroot pigweed and other troublesome weeds, and we can use from that for integrated weed management.

In order to Evaluation of suitable seed moisture content at harvest on vigour seed and some quality indices of two Oil-seed rape cultivars an experimental was conducted in 2007- 2009 in Dezfoul area. Therefore, samples of Hyola 401 and Hyola 308 seeds at 10%, 15%, 25% and 35% moisture content at harvest were taken from the field and tested at seed analysis laboratory. Some seed quality indices like germination percentage (seed viability), mean of daily germination speed (MDG), daily germination speed (DGS), seedling length, fresh and dry seedling weight and seedling vigour index (seedling dry weight × viability) were measured. Data obtained using a 2×4 factorial experimental based on a completely randomized design with three replications were combined analysis. Results showed that characters were significantly different.Germination percentage, mean of daily germination speed (MDG), fresh and dry seedling weight and seedling vigour index (seedling dry weight × viability) affected by cultivar × seed moisture content × year interaction. The highest rate of mean daily germination speed (MDG), fresh and dry seedling weight and seedling vigour index (seedling dry weight × viability) were obtained at 15% seed moisture content. In addition, seedling vigour index of Hyola 401 was higher than Hyola 308. This results revealed that seed quality was affected by environmental factors. Seeds harvested at 15% moisture content showed the highest quality.

In order to determine the response of yield and yield components of corn to weed interference and weed free periods an experiment was conducted in Agricultural faculty of Hamedan in 2008. This experiment was a factorial experiment based on a randomized complete bloke design with three replications and twelve treatments. The treatments of experimental consisted of six initial weed-free periods in which plots were kept free of weeds for 0, 15, 25, 35, 45 and 55 days after crop emergence, and then weeds were allowed to grow until harvest and six initial weed-infested periods in which, weeds were allowed to grow for 0, 15, 25, 35, 45, and 55, after which the plots were kept free of weeds until harvest. Yield, yield components and total dry matter were determined at harvest.The effect of interference and weedfree of weeds on total dry matter, harvest index, number of kernel per rows, grain yield, were very significant but The effect of interference and weedfree of weeds on number of rows per ear were not significant. The effect of interference period of weeds on weight of 1000 kernel was significant but the effect of weed free period was not significant.

Sesame is one of the most important oilseed tropical plants. In order to investigate the effect of two plant growth regulators, Naphtalene acetic acid (NAA) and Benzylamino purine (BAP) on yield, yield components, oil and protein content of sesame genotypes an experiment was carried out at the research farm, Shahid Bahonar University of Kerman in growing season 2006. The studied factors were two plants growth regulators BAP NAA each of which containing three levels as well as control with four sesame genotypes (cultivars of Moghan and Karaj, Baft and Sirjan landraces) which distributed randomly using factorial experiment in randomized complete block design with three replications.Foliage spray at 30 ppm and 200 ppm of NAA and BAP concentrations were carried out at the beginning of flowering stage. The results of analysis of variance showed that NAA and BAP treated plants showed a better performance in yield, yield components and some parameters. The results indicated significant main and interaction effects for seed yield in the experiment. land races were better than cultivars with hormonal treatment. Also different genotypes had interaction effects for seed oil and protein percentages using treatments Yield components had positive correlation with seed yield but seed protein and oil percentages had negative correlation with seed yield. Higher seed yield belonged to Sirjan and Baft landraces but Moghan and Karaj cultivars had higher seed oil and protein percentages. So cultivation of breeding cultivars using plant growth regulators can increase the oil product.

In order to evaluate the effect of silicon and phosphorus applications on disease severity of rice blast, a field experiment was carried out in 2009 in a factorial experiment based on the complete randomized blocks design with four replications in Sari. The pure phosphorus was applied in three levels (0, 50 and 100 kg/ha) as (P2O5) and pure Silicon was applied in three levels (0, 500 and 1000 kg/ha). As (Ca SiO2). There was a significant difference in seed yield in 5% probability and the highest grain yield obtained by application of 1000 kg/ha Si and was 3849.5 kg/ha. There was significant difference in leaf blast at 5% probability whereas that the lowest leaf blast severity by application of 1000 kg/ha Si, leaded to reduction the disease severity up to 10% in comparison to the control. This amount of using Si reduced significantly the average of lesion diameter (10/48mm) in comparison to the control without using Si, too. The various rates of P, did not affect significantly on the percentages of leaf, neck, nod, and grain blast and also on the average of lesion diameters. The rates of Si did not affect on the number of infected nod, neck and grain. Based on the interaction effects of P and Si, applying 1000 kg/ha Si without P lead to reduction significantly the average diameter of blast lesion. In the rate of 100 kg/ha P and 1000 kg/ha Si in comparison without using Si, there was significant difference in the percentage of leaf blast. So, we can find that in contrast to using Si lonely, using Si and P together cannot affect significantly in different treats of rice blast.

Experiments were performed with 49 soybean genotypes from I II and III maturity groups on base of lattice 7*7 designs at two replications and two levels normal (60 mm) and stress (150mm) in field of seed and plant breeding research institute in karaj in summer of 1383. At duration of the experiments were took notes from phenologic traits and were took notes from yield, yield components, oil and protein percents after field harvest, too.Results of analysis of variance indicated a good diversity between genotypes for almost traits. Path and stepwise regression analysis showed seed number in plant and biomass have most effects on yield in normal and stress conditions, respectively. Factor analysis indicated 5 affected factors in normal condition and 4 affected factors in stress conditions.Traits such as pod on reproductive nodules, plant seed number associated with yield in normal conditions and characters such as 100seed weight, root weight and biomass associated with yield in stress conditions, too. Calculation of resistance indices and biplot analysis divided genotypes to 4 groups and indices such as MP, STI, GMP and Harm were recognized as best drought indices in soybean. Obtained results of biplot analysis and drought resistance indices recognized genotypes such as Maccon, cysen, L.D.8149 have high yield and drought resistance and genotypes such as Korona, Hadgson and Enterprise have low yield and susceptible to drought.

Some plants have the ability in absorbing adequate amounts of some toxic and heavy metals. Although heavy metals contribute in the occurrence of oxidative stress in plant species, the plants possess various defensive mechanisms against the toxicity of such elements. One of these mechanisms is the activation of antioxidant enzymes in order to protect against oxidative injuries resulting from heavy metals. The aim of the present study was to understand the enzymatic changes of Catalase and Glutathione peroxidase in Grass pea (Lathyrus sativus) under lead and copper toxicity. In addition, the measurement of the ability in accumulating lead and copper and the effects of these elements on protein and the plant cell nucleus was another purpose of the present study. The experiment was carried out in factorial form as randomized complete design in agricultural and natural resources faculty, Karaj, in 2009. Four levels of lead (Pb (NO)3)2 (0, 200, 400 and 800 mg/kg) and four levels of copper (Cu (SO4) 2) (0, 150, 300, 450 mg/kg) were used. The results suggested the significant increase in lead and copper accumulation under different levels of the same elements (p<0.01), besides the measurement of Dityrosine and 8-hydroxy-2-deoxyguanosine contents, which increase during the peroxidation of protein and the plant cell nucleus respectively, was significant (p<0.01).The maximum toxic effects of the elements were observed at concentrations 800 and 450 mg lead and copper. The significant increase in both enzymes Catalase and Glutathione peroxidase was in response to the toxicity of the elements along with the increase in the different levels of lead and copper (p<0.01) so the remarkable increase in the activity of the two mentioned enzymes was observed at the maximum concentrations of soil lead (800 mg/kg) and copper (450 mg/kg).