Journal of Plant Ecophysiology
Volume:1 Issue: 3, 2009

The objective of the study was to determine important agronomic traits of sweet corn hybrids under weeds fully controlled and not-controlled conditions at different plant densities. The study was carried out in Hajiabad, Hormozgan, Iran in 2006. It was a split-split plot design based on a randomized complete block design with four replications. The main plots included sweet corn hybrids, namely KSC403 and Shimmer, the sub-plots included two levels, namely weeds fully controlled and not-controlled conditions, and the sub-sub-plots included three densities of 53000, 67000 and 89000 plants/ha. The results of analysis of variance showed that the variations of Shimmer and KSC403 in grain yield, 100-grain weight, grain number/row and row number/ear were significant. Also, weeds full control increased the grain yield by 7.8%. The highest grain yield was 9700 kg/ha for Shimmer at the density of 89000 plants/ha under weeds fully controlled conditions. In total, Shimmer exhibited superior traits over KSC403. In addition, Shimmer produced the highest grain yield at the density of 89000 plants/ha under weeds fully controlled conditions.

In order to determine the effects of water deficit stress on some morphological traits of alfalfa cultivars in Jiroft, Iran, an experiment was conducted in the fields of Agricultural Research Center of Jiroft in 2005-2006. It was a split-plot experiment based on a Randomized Complete Block Design with three replications, in which water deficit stress at three levels [including severe stress (irrigation when soil moisture was 25% of field capacity), moderate stress (irrigation when soil moisture was 50% of field capacity) and mild stress (irrigation when soil moisture was 75% of field capacity)] made the main plot and alfalfa cultivars at five levels (Yazdi, Nikshahri, Ranger, Bami and Baghdadi) made the sub-plot. The results of six sequential cuttings showed that water deficit stress significantly affected all morphological traits except internode length. The effect of cultivar was significant at 1% level on all traits except leaf/stem ratio and node number. With the increase in the intensity of drought stress, fresh forage yield, dry forage yield, stem length, stem number/unit area, leaf area index, internode length and internode number decreased but leaf/stem ratio increased. Dry forage had the highest correlation with plant height, stem number/unit area and leaf area index. Leaf/stem ratio had a negative correlation with forage yield. Finally, the cultivars Nikshahri and Bami were selected as drought-resistant cultivars, Baghdadi and Yazdi were selected as semi-drought-resistant cultivars and Ranger was selected as drought-sensitive cultivar in the region.

We aimed at studying the effects of seed priming on agronomic traits in maize using NaCl solutions containing different salt concentrations. The study was carried out in Valiasr University of Rafsanjan, Iran in 2009. A factorial experiment based on a completely randomized design with three replications was applied. Salinity treatments were 0, 4, 8 and 12 dS.m-1 and salt solutions for priming were 0.0, 0.5 and 1.0 molar NaCl. Seed characteristics like shoot dry weight, stem length, number of leaves, leaf area, chlorophyll and ion leakage were measured. The results of analysis of variance showed that the effects of salinity and seed priming on shoot dry weight, stem length, number of leaves, leaf area, chlorophyll and ion leakage were significant at the probability level of 1% (P< 0.01). The increase in salinity up to 12 dS.m-1 negatively influenced all traits except ion leakage and the amounts of reduction for the mentioned traits were 75.67, 52.25, 25, 69.97 and 21.17%, respectively, as compared with the control. In the case of ion leakage, the difference was 3.03 times less than that of control. Seed priming compensated the negative effects of salinity on plant traits and all the traits positively responded to the treatment of seed priming. Results showed that seed priming with NaCl may be considered as a reliable procedure to increase the maize tolerance to salinity.

In order to study the effect of manganese on yield of canola, cv. Hayola-308 in Jiroft, Iran, an experiment was conducted as autumn planting during 2008-2009. The experiment was laid out as a split-plot experiment based on a Randomized Complete Block Design with four replications. The two factors were manganese sulfate spraying (main plot) at two levels of 0 and 0.5% and manganese sulfate soil application (sub-plot) at three levels of 0, 40 and 80 kg/ha. During the experiment, different morphological and quality traits including plant height, pod length, capsule number/plant, grain number/capsule, grain yield, biomass, 1000-grain weight, and oil percentage were measured. Results showed that as Mn fertilizer level increased, plant height, grain number/capsule and oil percentage increased but 1000-grain weight decreased. Mn fertilizer treatments did not affect pod length, capsule number/plant, grain number and biomass. Results suggested that soil application of manganese would be mildly more effective than its foliar application.

In order to study the relation between sink and source in corn plants, a field experiment was conducted as a factorial experiment in a Randomized Complete Block Design with three replications. A total of 3 cultivars (301, 604 and 700) and four leaf clippings (without leaf clipping, ear leaf clipping, above ear leaf clipping, and below ear leaf clipping) were used during 2007 crop season. Results showed that oil, grain yield, globulin, glutamine, and carbohydrates were different among cultivars and treatment compositions. Leaf clipping did not affect oil, globulin and carbohydrates but yield and other quality traits were influenced by leaf clipping. Grain yield reduction was observed in 700, 406 and 301 in ascending order. The highest grain yield was observed in all cultivars under control treatment. Ear leaf clipping and below ear leaf defoliation ranked second for yield production. The lowest yield was observed in above ear leaf clipping treatment. Overall, all leaf clipping treatments produced similar amounts of oil, globulin and carbohydrates. The highest glutamine was obtained in above ear leaf clipping that was similar with ear leaf clipping treatment. Control treatment had the lowest glutamine similar to ear leaf clipping and below ear leaf clipping treatments. Above ear leaf clipping strongly increased grain prolamine and albumin. The lowest prolamine was obtained from below ear leaf clipping and without leaf clipping treatments. but the minimum grain albumin was belonged to ear leaf clipping. Leaf clipping treatments were ranked in four different groups with aspect to grain albumin concentration whereas control and below leaf clipping treatments had no difference in grain prolamine. The highest oil, globulin, glutamine, prolamine and carbohydrate belonged to the cultivar 604. Globulin concentration in grain of 604 and 700 cultivars and prolamine in grain of 604 and 301 cultivars were similar. Cultivar 301 produced the lowest globulin and prolamine but its oil, glutamine and carbohydrates were similar to 700 and 301 cultivars. Cultivar 700 produced the highest albumins under above ear leaf clipping treatment.

To study the production efficiency of four sunflower cultivars and hybrids introduced for cold regions under different moisture stress levels, a split-plot experiment was carried out on the basis of Randomized Complete Block Design with three replications in experimental field of Agriculture and Natural Resources Research Center, Zanjan, Iran in 2009. The stress treatment included four levels (no-water stress, stress at head formation stage, stress at flowering stage and stress at grain filling period) and the cultivars included Master and Lakomka and two hybrids Euroflour and Azargol. At harvest, the traits which were measured included head size/plant, grain number/head, growth period duration, 1000-grain weight, biological yield, harvest index and grain yield. The data were statistically analyzed and the means were compared by Duncan's multiple range test (DMRT) at 5% level when the effects of treatments were significant. For this comparison, the software MSTATC and MS-Excel were used. The results showed that Azargol had the highest yield under no-stress conditions and Master had the lowest yield under stress at head formation stage. Azargol had higher yield under both stress and no-stress conditions than the other cultivars. Also, the stress from head formation until the end of growing season had the highest effect on yield components, especially 1000-grain weight and head diameter because the plants were exposed to drought stress for a longer time. Head diameter is one of the essential traits which is decreased by moisture stress and adversely affects yield components such as grain number/head. No-stress treatment had the greatest head diameter whereas the stress at head formation stage had the lowest head diameter. No-stress condition and Lakomka had the highest 1000-grain weight (78.85 and 80.24 g, respectively) while the stress at head formation stage and Euroflour had the lowest one (64.03 and 64.4 g, respectively). In the case of grain number/head, the differences among different moisture stress levels and the interactions between stress and cultivar were not significant, but the cultivars affected this trait at 1% level, so that Azargol and Euroflour had the highest grain number and Master and Lakomka had the lowest one. The results indicated that drought stress severely affected biological yield and decreased it, so that the longer the duration of stress was, the shorter the growth period, the lower the photosynthesizing area and hence, the lower the yield were.

In order to evaluate the yield and grain yield components of corn hybrids in two successive planting dates under Karaj conditions, two experiments were conducted at Seed and Plant Certification and Registration Institute (SPCRI). The experiments were carried out in a split plot design based on randomized complete blocks with four replications. In this research, five levels of biofertilizers (control, three different levels of Humiforte, Aminol-forte, fosnutren and kadostim and also a combined level of Aminol-forte-Humiforte and kadostim-fosnutren) were arranged in main plots and three maize hybrids (including SC704, SC500 and SC260) were regarded as the sub-plots. Some traits such as grain yield, grain row number, grain number/row, 1000-grain weight and total grain number/ear were studied. The results of variance analysis in the first planting date disclosed that the effects of different fertilizers, different hybrids and also their interactions on grain yield were not significant, while the results of second planting date showed that different corn hybrids had significant effects on grain yield. Mean comparisons of two successive planting dates revealed that the cultivar 704 produced the highest yield (14.31 and 14.17 t/ha, respectively).

In many crop species, seed germination and early seedling growth are the most sensitive stages to stress. Salinity and drought may delay the onset, reduce the rate and increase the dispersion of germination events, leading to reductions in plant growth and final crop yield. The adverse effects of salt stress can be alleviated by various measures, including seed priming (pre-sowing seed treatment). The general purpose of seed priming is to partially hydrate the seed to a point where germination processes are begun but not completed. Most priming treatments involve imbibing seed with restricted amounts of water to allow sufficient hydration and advancement of metabolic processes but preventing germination or loss of desiccation tolerance. The objective of this study was to determine factors responsible for delayed germination and early seedling growth due to salt toxicity or osmotic effect and to optimize the best priming treatment for these stress conditions. In this experiment, treated seeds (control, KNO3 and hydropriming) of canola (Brassica napus L. cv. Okapi) were evaluated at germination and seedling growth stages for tolerance to salt (NaCl) and drought conditions (PEG-6000) at the same water potentials of 0.0, −3, −6, −9 and −12 bar. Electrical conductivity (EC) values of the NaCl solutions were 0, 3, 6, 9 and 12 dS.m−1, respectively. Results showed that germination delayed in both solutions, being variable with different priming treatments. Germination, and root and shoot length were higher, but mean germination time and unusual germination percentage were lower in NaCl than in PEG at the same water potential. Seeds were germinated at all concentrations of NaCl, but no seed germination was observed at −12 MPa of PEG treatments. NaCl had less inhibiting effect on the seedling growth than the germination. It was concluded that inhibition of germination at the same water potential of NaCl and PEG resulted from osmotic effect rather than salt toxicity. Hydro priming increased germination and seedling growth under salt and drought stresses.

In order to study the effects of foliar application of gibberellic acid on maize (hybrid BC504) in different planting dates, a field experiment was carried out in Sarabchengaee Agriculture Research Station in Khorramabad, Iran in 2006. The experiment was laid out as a split plot design based on Randomized Complete Block Design with four replications, in which planting dates constituted the main plot with three levels (June 7, June 21 and July 5) and gibberellic acid constituted the sub-plot with four levels (control, 0 ppm, 5 ppm, 50 ppm and 250 ppm, amounting to 400 liters/ha). Results showed that variation in planting dates had a significant effect on plant height, grain yield, 1000-seed weight and days to flowering. Gibberellic acid and its interaction with planting date did not have a significant effect on the studied traits.