Journal of Plant Ecophysiology
Volume:1 Issue: 1, 2009

The study was carried out under greenhouse conditions in two experiments: first experiment was designed to compare the effects of iso-osmotic treatments (150 mM NaCl and 20% PEG-6000 solutions) on stomatal conductance, leaf water potential and leaf relative water content in pistachio seedlings. Three-month-old seedlings of Pistacia atlantica subsp.
mutica, Pistacia vera “Sarakhs”, and Pistacia vera “Badami” were exposed to different treatments. The experiment was a factorial combination of three seedling rootstocks and three treatments, each replicated three times, and arranged in a randomized complete block design. Sampling for relative water content, water potential and stomatal conductance were carried out on 1st, 7th, and 14th days after application of treatments. In the second experiment, 36-month-old seedlings of the three rootstocks of pistachio were used. They were irrigated daily with two levels of salt solution (0 and 150 mM NaCl)
imposed by the stepwise method. The experiment was a factorial combination of three seedling rootstocks and two treatments, each replicated five times, and arranged in a randomized complete block design. Harvesting was carried out on the 10th day after salinization for measurement of ABA in xylem sap. Stomatal conductance in the controls showed little change throughout the experiment, although there were consistent cultivar differences, with P. atlantica subsp. mutica having the highest and P. vera “Badami” having the lowest values throughout. In the stress treatments, stomatal conductances
decreased gradually over time with the NaCl treatment showing more powerful effects than the PEG treatment. The leaf water potential and leaf water content of salt and polyethylene glycol-treated plants decreased over time and P. vera “Badami” plants showed significantly lower potentials than the other seedlings by 14 days after treatment. Water content was lower in 150 mM NaCl-treated plants than in 20% PEG because non-osmotic, perhaps toxic effects of NaCl increased cellular water loss. The data detected that ABA levels in P. atlantica subsp. mutica and P. vera “Badami” increased about 2-fold above the controls, but in P. vera “Sarakhs” it showed a 1.5-fold increase. ANOVA revealed that stomatal conductance measured on the same plants which were sampled for ABA levels in the xylem sap increased with the increase in salinity. These data suggest that xerophytic plants such as pistachio, which are adapted to arid environments, may show much reduced sensitivity in their ABA response system.

It is just a few years that canola (Brassica napus L.) is grown in Kerman Province, Iran, and little information is available on its response to nitrogen (N) and phosphorous (P) fertilizers. Therefore, a 2-yr field study as a split plot design was conducted at Shahid Zendehrooh Education Center in Kerman, investigating the influence of two sowing dates, early to late Oct. (main plots) and N and P fertilizers (sub-plots) in 3 replications. Canola was sown after barley and alfalfa in 1st and 2nd year of sowing respectively. In early Oct sowing of 1st yr, N and P fertilizers were applied at 300 and 50 kg ha-1 rates for a seed yield of 3.4 t ha-1. Results indicated that in the 2nd year, alfalfa had enriched the soil with N; therefore, for a seed yield of 3.9 t ha-1 in early Oct. sowing, 200 kg N ha-1 was applied while 300 kg N ha-1 reduced the seed yield. Delaying sowing reduced total N concentration in young leaves while decreased seed, oil and protein production. It could be concluded that sowing date, fertilizers application according to soil test results and planting canola after a legume were factors affecting optimum canola yield.

The study was carried out based on the data collected in Ardabil Synoptic Station, Iran (Lat. 48°17´ E., Long. 38°15´ N., Alt. 1314 m from sea level) for 26 years (1976-2001). To determine the climate of Ardabil, the components hydro-climate curve, Ambrothermic diagram (Walter and Gusen methods), Kupen method, Ivanov moisture coefficient, Ambergeh precipitation coefficient, Dumarthone drought coefficient and hytrograph curve were used. In addition, the variations of 12 meteorological variables were compared by simple linear regression. Ardabil hydroclimate curve showed that precipitation exceeds evapotranspiration by about mid-March and stored moisture can be used by about May 1st. From May to mid-October, during which precipitation exceeds evapotranspiration again, the crops are dependent on irrigation for their moisture requirement. Walter method (P = 2T) identified four months i.e. June, July, August and September as dry months of Ardabil and Gusen method (P = T/2) identified July and August as dry months. The number of dry months decreased using Gusen, Walter and Thorntwhite methods, respectively. Different methods for determining Ardabil climate had different results. The climatic coefficients of Kupen, Ivanov (0.3186), Ambergeh and Dumarthone (16.07) identified the region as drier, respectively. In total, Ardabil region is on the border of dry and humid zones. Variation trends of climatic parameters showed that sunshine hours (0.754**) and average annual maximum relative humidity (0.548*) are increasing and soil surface temperature (-0.424*) is decreasing.

Zinc is considered as one of the most important micronutrients for safflower nutrition and has an obvious role on seed yield of this crop. In order to evaluate the effects of different Zinc rates on yield and yield components of 10 safflower genotypes, a field experiment was conducted during growing season of 2008-2009 in Jiroft. The experiment was carried out in a split plot design based on Randomized Complete Blocks with 3 replications. Zinc rates (Zinc sulphate) were arranged as main factor with 3 levels (0, 2 and 4 spraying times with a dosage of 2.5/1000) and 10 safflower genotypes consisting 7-433, Isfahan 28, Shiraz landrace, Gol-sefid, Isfahan landrace, Isfahan 14, Kashan landrace, Arak 2811, 22-191 and IL-111 as sub factor. Traits such as yield and yield components (head number/plant, seed number/head, head diameter, 1000-seed weight), culm length, number of branches, biological yield and harvest index were measured. Variance analysis showed that higher levels of Zinc had significant effect on biological yield, head number/plant, seed yield and harvest index, but it was insignificant for seed number/head, 1000-seed weight and number of branches. The highest seed and biological yields were obtained from 4 times Zinc spraying. The studied genotypes highly significantly affected all studied traits but head diameter. Interactions of Zinc rates and genotypes were highly significant for head number/plant, number of branches, seed yield and harvest index. Genotypes IL-111 and 22-191 with the highest 1000-seed weight, seed yield, biological yield, harvest index, head number/plant in 4 times Zinc spraying showed the best performance. Based on correlation coefficients analysis, seed yield showed positive significant correlation with head number/plant (0.568**), biological yield (0.735**). According to regression analysis results, head number/plant explained 36 percent of seed yield variation and entered as the first significant variable to the regression model, and it could be considered as the most important trait in increasing the yield among the studied traits.

In order to elucidate the effect of sowing date on oilseed rape (Brassica napus L.) yield and yield components, three varieties including Tower, Rafal and Global were sown from November 7 to December 22, 1998-99 in four dates with 15-day intervals in Dezful region. A split-plot design based on randomized complete blocks with four replications was used in which levels of sowing dates and cultivars formed the main and sub-plots, respectively. Variables including plant height, axillary branches/plant, pods/plant, seeds/pod, single seed weight, biomass, seed oil content and seed yield were measured. Results showed that the sowing date had a highly significant effect on morphological characteristics, yield components, oilseed rape yield and seed oil content. Delay in sowing date caused a reduction in all yield components, especially pods/plant and oilseed yield by 285.23 g/m2 to 135.57 g/m2 on November 7 and December 22, respectively. Variations in sowing dates had different effects on yield components and reduction rates of pods/plant, seeds/pod and single seed weight. The significant effect of variety on all characters, except single seed weight indicated that there were genetic differences among the studied cultivars. Oilseed yield had the significant positive correlations with pods/plant (r = 0.93), single seed weight (r = 0.83) and seeds/pod (r = 0.66). The results of path analysis showed that pods/plant and seeds/pod had the highest positive and negative effects on oilseed yield, respectively. Finally, considering the susceptibility of pods/plant to variations of sowing date and the important role of this character in oilseed yield production, the delay in sowing date in Dezful region reduced the oilseed yield by decreasing pods/plant.

In order to determine the effects of sowing date on grain development in four maize hybrids, a field experiment was carried out as a RCBD in split plot arrangement with three replications at experimental farm of Islamic Azad University of Jiroft, Iran (Lat. 26.43°N., Long. 56.17°E., Alt. 620 m.) in 2006. Main factor included four sowing dates (July 16, August 1, August 16 and September 1) and sub-factor included four hybrids (ZP434, BC504, NS540 and KSC704). During grain filling period, grain samples were taken in five different times and their grain dry weights were measured. Grain filling rate, effective filling period and kernel weight were determined. Results showed significant differences among the genotypes and sowing dates, while their interaction was not significant. Grain weight variation trends during grain filling period could be explained by an exponential equation. Delayed sowing date reduced the grain filling rate and grain weight by nearly 50% and 30%, respectively and increased the effective filling period by about 17%. The fastest grain filling rate was observed in NS504; hybrids KSC704 and ZP434 were moderate and NS540 showed the slowest grain filling rate.

Old wheat varieties are regarded as useful genetic resources to transfer desirable genes in breeding programs especially in arid zones. On the other hand, modern cultivars have better responses to the inputs application increases, but there have been contradictory reports about the relative advantage of old varieties for cultivation on poor soils. The experiment was carried out in Agricultural Research Station of Islamic Azad University of Ardabil, Iran in 2008-09 to study the responses of old and modern bread wheat cultivars to different nitrogen (N) levels and seeding rate. A factorial split-plot experiment based on a Randomized Complete Blocks Design (RCBD) with three replications was used. The combinations of N levels (54 and 108 kg N.ha-1) with two seeding rates (250 and 400 seeds.m-2) were regarded as main plots and 44 cultivars (15 modern and 29 old bread wheat cultivars) as sub-plots. The results showed that new cultivars produced significantly (P<0.01) greater grain yield than old cultivars (527.18 and 449.41 g.m-2, respectively). The increase was only observed in grain yield, and straw yield was not affected by cultivar. Consequently, Harvest Index (HI) of modern cultivars (0.35) was 13% greater than that of old cultivars (0.31). Modern cultivars had 12% less spikes.m-2 and 26% more grains.spike-1 than old cultivars, but the single grain weights of modern and old cultivars were not significantly different. The cultivars did not have significant differences regarding total tiller number while fertile tiller number was significantly lower in new cultivars (2.30) than in old cultivars (2.57). The decrease in plant height of modern cultivars compared to old ones (11.23 cm) was due to the decrease in internode length (by 2.8 cm.internode-1) and not the node number.