Journal of Water and Soil Science
Year:2008 | Volume:11 | Issue:42 (A)|Papers Count:27

In order to study the effects of different levels of irrigation, nitrogen and plant population on yield, yield components and reserved dry matter remobilization of seed corn (SC. 704 hybrid) a research was conducted at the experimental field in Khuzestan Natural Resources and Agricultural Science University in summer, 2004. This research was made based on three split-plot field experiments, RCBD. Each of the irrigation treatments implemented separately in each experiment have been as follows: Optimum irrigation, Moderate stress and Severe stress (irrigation after drainage 50%, 75% and 100% of available water based on 70%, 60% and 50% of field capacity, respectively). In each experiment three nitrogen levels consisting of 140 (N1), 180 (N2) and 220 (N3) Kg N ha-1 were applied in main plots and subplots which consisted of three plant populations (D1=6, D2=7.5 and D3=9 plant m-2). There were three replications for each experiment. The results of the combined analysis of variance indicated that the effect of water deficiency stress, nitrogen and plant population on grain and biological yield was significant. With increasing severity of drought stress, the grain and biological yield decreased. The maximum grain yield was estimated to be 1017.04 gm-2 which was related to optimum irrigation treatment. Grain yield reduction was mainly due to reduction of grain per ear and 1000 seed weight. The increase of nitrogen consumption caused an increase in grain yield. The positive effect of nitrogen application on grain yield considerably decreased as a result of the increased water deficiency in soil. The response of grain yield to plant population was positive. The contrary to interaction effects of irrigation and nitrogen, and irrigation, nitrogen and plant population, the interaction effects of irrigation and plant population and also nitrogen and plant population on grain yield were significant. The results indicated that the difference between different levels of irrigation in the case of dry matter remobilization rate was significant. The least and the highest remobilization rate of reserved dry matter was related to optimum irrigation and drought moderate stress treatment, respectively. The efficiency and contribution of remobilization in grain yield increased in response to increasing severity of drought stress, but these traits significantly reduced as a result of nitrogen consumption. Remobilization rate and contribution of reserved materials to grain yield in the highest density (D3) were significantly more than other densities. According to the results of this study, under drought stress conditions, the decrease of inputs consumption, in addition to the decrease of costs, will be followed by the increasing efficiency use of the resources.

Planting patterns through growth indices affect yield formation. To evaluate these effects on safflower, Koseh local variety of Isfahan, a field experiment was conducted in summer, 2004 at the Agricultural Research Station, Isfahan University of Technology. The experiment was performed using a randomized complete block design with a split plot layout and four replications. Main plots consisted of three row distances (20 and 30 cm flat and 45 cm on bed), and subplots included two planting densities (40 and 50 plant m-2). The experiment was planted on June 25. The results showed that plant canopy closed sooner, leaf area duration (LAD) increased and plant dry matter weight, leaf area index (LAI) and crop growth rate (CGR) were higher up to the middle of seed development as row distance decreased. In addition, the highest relative growth rate (RGR) and net assimilation rate (NAR) were obtained in 20 cm row distance. The highest (3039 kg ha-1) and lowest (1930 kg ha-1) seed yields were obtained with 20 and 40 cm row distances, respectively. Plant density did not affect the rate of canopy closure, CGR, RGR, NAR and seed yield. But, maximum plant dry weight, higher LAI and lower LAD values were obtained with 50 plants m-2. The results obtained in this experiment indicate that 20 cm row distance with 50 plants m-2 might be appropriate for summer planting of safflower, a local variety of Isfahan, under similar conditions.

Parsi Zira, Bunium persicum (Boiss.) B. Fedtsch., which is called Mountainous or Black Zira, is one of the most important medicinal plants with high economic importance. Generally, there is a little information about in vitro culture of Bunium persicum. Fragmented embryo was used as an explant in Bunium persicum regeneration. In this method, a great callus induction and regeneration only on the same medium without any subculture occurred because of being young and having better interaction with medium, leading to reduction of tissue culture time, infection and chemical consumption. In this research, B5 media containing different concentrations of plant growth regulators, NAA and 2,4-D only or together with Kin, were used. The experiment was conducted using completely randomized design with 30 treatments and 10 replications per treatment. The highest callus number was obtained from the treatment containing 0.1 mg/l 2,4-D and 2 mg/l Kin or 1 mg/l NAA and 2 mg/l Kin. Regeneration occurred in some treatments without Kinetin, showing that Kinetin is not essential for Bunium persicum regeneration. The treatment containing 0.1 mg/l NAA and 4 mg/l Kin was the best one for regeneration. The best treatment for somatic embryogenesis was 2 mg/l 2,4-D.

Application of selection index for screening desired plants based on complex quantitative traits can be more effective than direct selection. This study was conducted using an F2 rice population consisting of 87 plants derived from a cross between two cultivars Gharib and IR28. The purpose was to establish suitable selection indices for increasing yield and its related traits in research farm of Rice Research Institute of Iran (RRII), Rasht, in 2005. Studied traits included the days from sowing, germinated grain to maturity (MD), plant height (PH), panicle length (PL), flag leaf length (FL), flag leaf width (FW), number of panicles per plant (PP), number of grains per panicle (GP), number of spikelets per panicle (SP), 100-grain weight (GW), grain yield per plant (GY), biomass (BM), harvest index (HI), grain length (GL) and grain breadth (GB). Among the studied traits, 100-grain weight (GW), biomass (BM) and harvest index (HI) (0.99) and flag leaf width (FW) (0.35) showed the highest and lowest broad-sense heritability, respectively. Path coefficient analysis revealed that BM, HI, GP had positive direct effects on GY. Calculation of five different selection indices based on optimum and base indices indicated that selection for BM, HI and GP using genotypic path coefficients and their heritability as economic values would be a suitable selection criterion for improving population. Moreover, this study showed that both optimum and base indices show the same genetic progress for the studied traits. Since evaluation of base index, is much easier than the optimum index, it is highly recommended.

Sugarcane is one of the most important sugar crops in the world. Because of semi-arid climate and salinity of its cultivation area in our country, increasing salt tolerance of sugarcane is signifying. To achieve this goal determining salt tolerant cultivars and understanding salinity mechanisms in sugarcane are very important. This study was conducted to evaluate 8 commercial and promising sugarcane cultivars at early stage of growth. A complete randomized design with three replicates and four salinity treatments (0, 0.25, 0.5, 0.75 % NaCl) was used in a hydroponics system. The effect of salinity on absorption, transport and accumulation of Na+, Cl- , K+ and Ca2+ ions in shoot and root was determined. At high level salt concentration, Cl- content in shoot and root increased. Result showed that sodium accumulation in sugarcane plants was more than potassium. By increasing salinity level, sodium uptake and its translocation to shoots increased reducing growth and dry matter yield of plants. With rising salt concentration from medium (0.5%) to high (0.75%), content of chloride in shoot and root of NCO-310 was constant showed that this cultivar had genetic ability to avoid Cl- uptake. CP82-1592 with lowest ratio of shoot / root chloride had minimum transport of Cl- to shoots. Also this cultivar had high content of Ca2+ in shoot and low Na+/Ca2+ ratio at all salinity levels. CP48-103 had low sodium in shoot and relatively low sodium in root. Thus it probably has genetic potential to avoid sodium uptake. At last, exclusion of Na+ and Cl- to older leaves and tillers was seen in CP82-1592 and CP72-2086 cultivars. According to results, to avoid once of absorption and transport, and exclusion of harmful Na+ and Cl- ions were mechanisms that could be used in salinity tolerance of sugarcane.

During the past years, safflower genotypes have been selected from local variety of Isfahan, named Kouseh. The response of these genotypes to planting date might be different. To determine this, performances of several genotypes selected from Kouseh plus Arak 2811 (as check) were studied at the Agricultural Research Station, Isfahan University of Technology in 2002-2004. The experiment was conducted using a split-plot arrangement within a randomized complete block design with three replications. Planting dates were considered as the main plots and subplots consisted of 22 genotypes of safflower. Number of days from planting to emergence was highest (18.0 days) in early spring planting and lowest (10.3 days) in late spring planting. Days from planting to head visible, flowering and physiological maturity were decreased with delay in planting from autumn to late spring. Days from planting to emergence, head visible and physiological maturity were not influenced by genotype. Genotypes C116 and DP29 had the highest (145.0) and genotype ISF28 the lowest (140.2) days from planting to flowering. Plant height, number of first and second degree branches, number of heads per first and second degree branches, number of seeds per head, 1000-seed weight and seed weight per plant reduced significantly with delay in planting from autumn to late spring. Genotypes C128 and DP7 had the highest (120.0 and 120.5 cm, respectively) and genotype DP9 the lowest (104.2 cm) plant height. Genotypes DP6 and DP9 had the highest (12.8) and the lowest (6.7) first degree branches per plant, respectively. Arak-2811 had the highest (16.9) and genotypes DP9 and DP5 the lowest (7.2 and 7.1, respectively) second degree branches per plant. Number of heads per first degree branches was not significantly affected by genotype. Arak-2811 and genotype C114 had the highest (12.8 and 12.2, respectively) and genotype DP9 the lowest (5.1) number of heads per second degree branches. Genotype DP7 had the highest (45.9) and genotype C111 had the lowest (28.0) number of seeds per head. Genotypes DP3 and C128 had the highest (34.2 g) and lowest (22.0 g) 1000-seed weight, respectively. Genotype DP25 had the highest (20.5 g) and genotypes DP29 and DP9 the lowest (9.9 and 10.0 g) seed weight per plant. Harvest index was not affected by planting date and genotype. The result of this study showed that safflower may yield more in fall planting under conditions similar to this experiment. Genotype DP25 might be recommended for this planting date, genotypes ISF66 and DP25 for early spring planting and genotypes DP7 and ISF14 for summer planting.

In order to reduce the rainfall damages on rice yield at harvest stage, a field experiment was conducted at Rice Research Institute of Iran, Rasht, in 2004 by using Sodium Chlorate as a chemical desiccant. Five seed moisture contents of Dorfak rice cultivar were considered as experimantal treatments [24 - 28% (M1), 22 - 24% (M2), 20 -22% (M3). 18 - 20% (M4) and control (M5= conventional harvesting)]. The experiment was carried out in a randomized complete block design with three replications and the effects of treatments on grain yield, head rice yield,seed germination rate and percentage, kernel breakage, kernel cracking, amylose content, gelatinization temperature and gel consistency were evaluated. Results showed that the whole plant and grain moisture contents were significantly reduced in all experimental treatments compared with control. M2 and M3 both cosiderably reduced the plant moisture content in which harvesting occurred 12 and 8 days respectively sooner than the control. In M1, due to high grain moisture and non - simultaneous grain filling in different tillers, many of panicles desiccated prior to maturity lost their quality. In M4, the crop harvested was only 2 days earlier than the control. Analysis of variance showed that there were no significant effects of treatments on evaluated traits. It seems that rice plant could be reliably desiccated by Sodium Chlorat and harvested earlier without any adverse effects on its quality and quantity.

The response of bread wheat genotypes to weed interference was evaluated under dryland conditions. An experiment was conducted with 26 genotypes of bread wheat and two known cultivars, Sardari and Azar2, as checks in a strip plot (Split block) arrangement based on Randomized Complete Block Design (RCBD) with four replications in 2002-03 at Dryland Agricultural Research Institute, Srarood, Kermanshah. Weed-free and weedyconditions were assigned to horizontal factor with genotypes as vertical factor. Plant height, number of seeds per spike, number of spikes per square meter, grain yield, weed density and dry matter, and indices of Weed Interference Tolelance Index (WITI) and Competition Index (CI) were recorded. Mean comparison showed that genotypes 13, 1, 26 and 8 had higher grain yield than those of checks under both weed-free and weedy conditions. These genotypes also had higher WITI in comparison with the checks. According to CI values, genotypes No. 1, 9, 13, 26 and 27 including checks had a high potential of weed competition. Results of stepwise regression analysis based on WITI as the dependent variable indicated that the number of spike, plant height and number of seed per spike had positive and significant effects on WITI. On the wole, considering WITI and grain yield as two main attributes, genotypes 13, 26, 1 and 8 were selected as appropriate since they showed a high weed competitive ability and also produced higher grain yields under both weedy and weed-free conditions.

Evaluation of genetic improvement of grain yield and other traits in cultivars released in different years is useful to determine plant breeding impact on grain yield improvement, to define future selection criteria and to identify the desirable environment and traits for further assessment. This study was conducted to evaluate the genetic improvement for grain yield and other traits of twelve oat (Avena sativa L.) cultivars released in Canada during 1921- 1997, at Research Farm, College of Agriculture, Isfahan University of Technology, during 2001-3 in a randomized complete block design with three replications. The regression of mean grain yield on released year of the cultivars showed that the rate of increase in grain yield during a 76-year period is 32.63 kg h-1 year-1 or 0.63% per year. Breeding programmes have inereased harvest index, grain number per panicle and fertile tillers /m2. The effort of breeders in this period was to decrease plant height and days to heading. The other traits had small changes and showed no specific trends. In general the results of this study showed continous improvement of grain yield in this period. Genetic improvement of grain yield in evaluated cultivars closely correlated with harvest index. Therefore, most variation in grain yield of oats was due to variation in harvest index. Although much of the improvement in grain yield described here could be attributed to the increased harvest index, the scope for further improvement in this character may be limited. Further yield improvement of oats might be achieved by combining high biological yield with high harvest index.

This study was conducted at Research Farm of Isfahan University of Technology to evaluate drought tolerance potential of 23 F2:4 wheat lines derived from the cross of Virmarin (susceptible line) and Sardari (tolerant line). A randomized complete block design with three replications was used in each irrigation treatment (i.e. irrigation after 70±3 and 120±3 mm evaporation from class A pan for non-stress and stress conditions, respectively). Drought tolerance and susceptibility indices were calculated for yield, and principal components analysis was performed on the basis of indices. Rosielle and Hambline tolerance index and Fisher and Maurer stress susceptibility index had positive and significant correlation, but their correlations with drought yield and the first two principal components were negative. High value of these components indicates low sensitivity to drought. The first component had high and positive correlations with geometric mean productivity, stress tolerance index and harmonic mean. Lines number 4, 17, 11 and 14 with high yields in drought condition, showed high values for these indices. Line number 2 with high yield in nonstress condition and in spite of high sensitivity to stress, was a superior genotype based on these indices.

This research was conducted in order to determine the relationship between grain yield and yield components, using 30 common bean varieties in a randomized complete block design with four replications at the Agricultural filed faculty of Agriculture, Tehran university In this study 18 traits were assessed on 10 random plants from each plot. The result showed that there were significant differences among varieties in terms of trait under study, indicating the existence of genetic variation among varieties. Also results showed that the grain yield had a positive and significant genotypic correlation with number of seed/pod, pod weight, number of pod/plant, biological yield, days to flowering and maturity. Stepwise regression analysis showed that the maximum variation in grain yield could be attributed to the number pod/plant, number seed/plant, 100 seed weight and pod length. The results of path analysis showed that the highest direct effect, being positive, was related to number seed/plant and the lowest direct effect, which was related to number pod/plant. Factor analysis resulted in three factors that accounted for 78/7% of total variation. The first factor accounted for 38.39% of total variation and was designated as yield and yield component factor. This factor is comprised of pod weight, biological yield, grain yield and number of pod/plant traits.

In this study, factor analysis was conducted to determine the factors which contributed to the variation of quantitative traits and path analysis was performed to find the direct and indirect effects of yield components on grain yield in bread wheat. A doubled haploid population of 157 lines of wheat (Triticum aestivum L.) was evaluated for agronomic and morphological traits, using a randomized complete block design with three replications in 2003 and 2004. The results of factor analysis based on maximum likelihood indicated five factors explaining 80.4% and 73.9% of total variation in 2003 and 2004, respectively. The first factor in 2003 had 30.5% contribution to the total variation, strongly influenced by the traits of pollination date, heading date, flag leaf length and days to maturity. This factor also indicated the negative relationship among the yield components and the importance of relationship between grain yield and some morphological traits. The first factor in 2004 was more affected by grain weight/spike, grains/spike and 1000-grain weight, thus it was named as grain yield factor. The second and third factors in 2003 were considered as plant height and grain yield and in 2004 as maturity and plant height, respectively. The results of path analysis showed that grains/spike had the most direct and positive effects on grain yield in 2003 (1.33) and 2004 (0.87). Because of the negative and high indirect effects of grains/spike via fertile spikes/m2 and 1000-grains weight on grain yield, the correlation coefficient between grain yield and grains/spike was very low. There was not much difference between the phenotypic and genetic direct effects of spike/m2 on grain yield, indicating that their relationship was less affected by environmental conditions. In general, the results showed that grains/spike and spikes/m2 can be more efficient compared to 1000- grains weight for increasing grain yield and can be used as selection indices in breeding programs. Also, according to the results of factor analysis, selection based on the fourth factor including biological yield, spike/m2 and grain yield as selection index can be effective to improve grain yield in breeding programs.

Photosynthesis and wheat grain yield responses to supplemental irrigation with different amount of applied water under dryland conditions were investigated. Therefore, a two-year field experiment was conducted research farm of College of Agriculture, Shiraz University during 2004-2005. Five levels of irrigation including dryland conditions, irrigation at stem elongation, booting, flowering and grain filling were main plots and two wheat cultivars: Agosta and Fin-15 were subplots, and three rates of nitrogen including zero, 40 and 80 kgha-1 were sub sub-plots. The results showed that in both years, photosynthetic rate, stomatal conductance, substomatal CO2 concentration and transpiration rate, were significantly higher under irrigation at stem elongation stage compared to other supplemental irrigation treatments. In all of the four supplemental irrigation treatments, photosynthetic rate, stomatal conductance, substomatal CO2 concentration and transpiration rate decreased with decreasing the amount of applied water to each plot. In both years, the highest grain yield was obtained from supplemental irrigation at stem elongation stage, and the lowest yield was harvested at dryland conditions. The highest photosynthetic parameters, yield and yield components were obtained from interaction of supplemental irrigation at stem elongation stage × Fin-15 and 80 kg N ha-1 in both years. The supplemental irrigation in 2004 and 2005 increased the grain yield 200 and 221 percent, respectively, compared to dryland conditions. Thus, supplemental irrigation at sensitive stem elongation stage could affect significantly wheat grain yield of rainfed wheat cultivars and provision of adequate water for a supplemental irrigation at the appropriate growth stage could double the grain yield of rainfed wheat.

An experiment was conducted to investigate the heterosis in 12 F1 hybrids of durum wheat using agronomic and morphological traits. Parents were selected according to the estimated genetic distances based on the results of a twoyear field experiment, which were then crossed to produce F1 hybrids. Twenty-three genotypes (including 11 parents and 12 hybrids) were evaluated using a randomized complete block design with three replications Research Farm of College of Agriculture, Isfahan University of Technology, located at Lavark, Najaf- Abad in 2003. Agronomic characteristics comprised days to 50% flowering, days to 50% pollination, days to maturity, plant height, spike length, grain weight per spike, number of grain per spike, number of spike per m2, 1000-grain weight, biological yield, grain yield and harvest index. The results of analysis of variance showed significant differences among parents; F1 hybrids and parents vs. crosses for all the studied traits. Substantial differences in the level of heterosis for plant maturity were detected among the hybrids with the highest heterosis belonging to HPI40100×PI40099 and HEupoda6× Chahba88 hybrids. Furthermore, superior hybrids included HAltar84/Ald×Chahba88, HBuchen7×Chahba88 and HEupoda6×Mexi75/Vic possessing the highest heterosis for grain yield and grain yield components among 12 hybrids of the present experiment. Eventually, it is concluded that Eupoda6, Odin12, Altar84/Ald and 45063Karaj genotypes when crossed with Mexi75/Vic genotype as well as Buchen7 and Altar84/Ald genotypes when crossed with Chahba88 genotype produced superior F1 hybrids.

Presence of genotype × environment interaction necessitates evaluation of genotypes in a wide range of environments to find desirable genotypes. This study was carried out to determine the stability and adaptability of grain yield of 17 chickpea genotypes, in RCBD with four replications at Kermanshah, Lorestan, Ilam, Gachsaran and Gorgan Research Stations during two seasons (2003-2004). The genotype×environment interaction effect analyzed using the additive main effects and multiplicative interaction (AMMI) statistical model was significant at 1% level of probability. The sum of squares of G×E interaction was partitioned by AMMI model into four significant interaction principal component axes (IPCA). The first four principal component axes (IPCA 1, 2, 3 and 4) cumulatively contributed to 94% of total genotype by environment interaction. A biplot generated using genotypic and environmental scores of the first two AMMI components also showed that genotypes FLIP 97-79, X95TH1 and FLIP 97-114 were selected as stable genotypes, among which the genotype FLIP 97-114 was outstanding for high yield stability.

The most desirable approach to improve characteristics such as yield with polygenic inheritance and genotype × environment interaction, is simultaneous selection using selection index based on related traits. This study was conducted Research Farm of Isfahan University of Technology, to compare selection indices for barley yield improvement under nitrogen stress and non stress conditions, using 49 F13 recombinant inbred lines derived from a cross between Azumamugi and Kanto Nakate Gold. A split plot design with randomized complete block layout in three replications was used. In non-stress condition 100 kg nitrogen per hectare as urea was used at early reproductive growth, stem elongation and grain filling stages. In stress condition, 50 kg nitrogen per hectare was only used at early vegetative growth stage. Smith-Hazel and Pesek-Baker indices based on 4 traits (days to heading, harvest index, growth rate and nitrogen harvest index) and also direct and correlated response of these traits were calculated. The result of response to selection and correlated response indicated that the selection based on higher harvest index and nitrogen harvest index under both conditions screens high yielding lines. Harvest index had high weight in both indices under stress and non stress conditions. Under both conditions and for Smith-Hazel and Pesek-Baker indices, growth rate had negative correlation coefficients. Therefore, the selection based on these indices, separates lines with lower growth rate. In this study, Smith-Hazel index had higher efficiency.

Navel oranges and Clementine mandarin are classified as early cultivars and when fruits are left on the trees, fruit firmness and juice content will decrease. Plant growth regulators have been used to improve fruit quality. Gibberellic acid (GA3) and 2,4-D isopropyl ester sprays were used to increase juice content ,peel firmness and delay senescence in Navel oranges and Clementine mandarin. Factorial experiments were arranged in a complete randomized block design with three replications and each block consisted of three trees. Chemicals were sprayed on the branches (north and south of each tree) with 10 liter sprayer to the point of run-off during fall of 2004 and 2005, in a commercial orchard in Jahrom in the south east of Fars province, Iran. In both years of study, GA3 at 100,150 and 200 mgl-1 and isopropyl ester 2,4-D at 8,12 and 24 mgl-1 were sprayed on September 30 (diameter of Navel 64 mm and diameter of Clementine 46 mm), October 14 (diameter of Navel 69 mm and diameter of Clementine 48 mm) and November 7 (diameter of Navel 70 mm and diameter of Clementine 50 mm) and fruits of Navel oranges and Clementine mandarin were harvested 45 and 35 days after last the spray treatment, respectively. The results of experiment revealed that Navel oranges responded better with second application (Oct.14, diameter 69 mm) and Clementine mandarin with the first application (Sept.30, diameter 46 mm). Juice content and fruit firmness at harvest increased. GA3 increased juice content even better than 2,4-D isopropyl ester but delayed senescence, 2,4-D was more effective in increasing fruit sizing in both cultivars. GA3 at 150 and 200 mgl-1 and 2,4-D at 24 mgl-1 when compared with the untreated resulted in highest juice content of fruits.