جستجوی مقالات مرتبط با کلیدواژه « تعداد برگ » در نشریات گروه « زراعت »

In order to investigate the effect of different methods and levels of irrigation water on some vegetative and reproductive characteristics of saffron, this research was carried out in the form of a split-plot experiment in the form of a randomized complete block design with three replications at the Razavi Khorasan Agricultural and Natural Resources Research and Training Center. (Gonabad Research Station) was carried out in the crop years of 2017-2018. In this research, irrigation method treatments (including basin, drip and sprinkler (Pflex) methods) were in the main plot and different levels of irrigation water (including supplying 100, 75 and 50% of the water requirement) were in the sub plot. Results The comparison of the averages showed that in both years of the experiment, changing the irrigation method from basin to drip (tape) and sprinkler (P-flex) led to an increase in the studied properties. Reducing the amount of irrigation water from 100% to 50% of the water requirement also caused a decrease in leaf characteristics and stigma yield, but the efficiency of irrigation water consumption increased. Based on this, reducing the water requirement of saffron from 100 to 50% in the first and second year caused a 33% and 30% decrease in stigma yield, and a 32% and 37% increase in water consumption efficiency, respectively. Examining the interaction effects table showed that in the first year of the experiment, reducing the amount of irrigation from 100 to 50% caused a greater reduction in the total length of leaves per square meter under drip irrigation (tape) than the other two irrigation methods (82% in the drip method (tape) in contrast to 79% in the sprinkler (P-flex) method and 69% in the basin method). Based on this, although the positive effect and relative advantage of modern irrigation systems is decreasing with the increase in the age of the farm, it seems that it is possible to achieve optimal performance in the region by using rain irrigation sprinkler (P-flex) method in 100% of the water requirement.

In order to investigate the effect of water stress and the application of potassium sulfate fertilizer on some growth characteristics of "Zahedi" date palm tissue culture-derived plants, this research was conducted as a factorial experiment based on a Randomized Complete Block Design with three replications on 45 plants. Water stress at three levels (Irrigation to the amount of 100, 80 and 60% of cumulative evaporation from Class A evaporation pan) and potassium sulfate fertilizer at five levels (zero, foliar application 2 g L-1 and 4 g L-1, soil application 50 g and 100 g for each plant) were applied to the plants. At the end of the experiment, the growth characteristics including trunk circumference, number of leaves, length and width of leaves, number of leaflets, length and width of leaflets, fresh and dry weight of aerial parts were measured and subjected to statistical analysis. The results showed that the increase in water stress had a significant negative effect on all vegetative growth traits, while the application of potassium sulfate moderated the effects of water stress. At the highest level of water stress (Irrigation to the amount of 60% of the water requirement) without application of potassium, the fresh and dry weight of aerial parts was recorded at 590 and 243 g respectively, but with the soil application of 100 g potassium sulfate at the same level of water stress, the fresh and dry weight of aerial parts increased significantly to 706 and 346, respectively. In this research, the soil application of potassium sulfate fertilizer had better effects on the growth characteristics of date palm plants than the foliar application method. In all levels of water stress, the application of potassium sulfate fertilizer, especially in soil application of 100 g for each plant, increased vegetative growth and fresh and dry weight of the date palm plant and improved its resistance to water stress.

Nowadays, agricultural products are moving towards organic farming in response to consumers' desire for healthier products. One of the ways to produce and increase yield in these conditions is using biological and organic inputs such as biochar and mycorrhiza. Therefore, this experiment was conducted at Safadasht Golazin Agro-industrial in Safadasht, Tehran, in order to investigate spinach yield. The experiment was carried out as split plots in the form of a randomized complete block design in 3 replications. The experimental treatments included four levels of control, two, four, and six tons per hectare of biochar as the main factor and two inoculation levels with mycorrhiza and control as secondary factors. The results showed that the effect of the investigated treatments on the measured traits was significant. The highest plant height (15.24 cm), total chlorophyll (2.44 mg/g fresh weight), root fresh weight (19.56 g), and shoot (30.95 g) at the application level of mycorrhiza and six tons of biochar per hectare was observed. The effectiveness of mycorrhiza increased with the increase of biochar level. In general, the results showed that the synergism effect of biochar and mycorrhiza increased the yield of spinach traits; this synergy can be one of the strategies to reduce the consumption of chemical fertilizers.

Proper plant density and emphasis on high density cultivating patterns and mother corm weight during the first years of cultivation to achieve high yield and reduce the length of the operation cycle of saffron farms, should be considered by farmers. The effects of plant density and mother corm weight on flower yield and growth characteristics of saffron were evaluated under field conditions. Treatments were three levels of plant density (100, 200 and 300 per m2) and three mother corm weights (0.1- 4, 4.1- 8 and 8.1- 12 g). The experiment was designed as factorial arrangement based on randomized complete block design with three replications at the Research station of Faculty of Agriculture University of Birjand during growing season of 2016-2017. The results indicated that plant density and corm weight had significant effect on the fresh weight of flower, fresh yield of flower, dry yield of stigma and fresh weight of leaf. There were significant different between some characteristics (fresh yield of flower and dry yield of stigma) by interaction plant density and corm weight treatments, so that, the highest fresh yield of flower and dry yield of stigma were obtained (9.88 and 2.41 kg/ha, respectively), from corm weight with 8.1-12 g and plant density with 300 corm/m2, and the lowest were observed from corm weight with 0.1-4 g and plant density of 100 corms per m2. The highest fresh weight of leaves and flower were obtained from 8.1-12 g and 300 corms per m2. Also, the highest and lowest attributes of flower were observed from corm weight with 8.1-12 g and 0.1-4 g, respectively. It was found that corm weight had significant effect on leaves characteristics (length, fresh weight and dry weight of leaf, chl a, chl b and total chl), so that the highest these attributes were obtained from corm weight with 8.1-12 g. In general, the use of corm weight 8.1-12 g and plant density 300 corms per m2 had an effective role in increasing the yield of saffron.

In order to investigate the effect of compensatory behavior of planting density, corm weight and planting depth on vegetative characteristics and yield of saffron stigma (Crocus. Sativus L.), a factorial split plot experiment with a randomized complete block design with three replications in the research center and Agricultural education and natural resources of Khorasan Razavi (Gonabad Research Station) was conducted in the cropping years 2018-2020. In this study, planting density treatment (in four levels of 60, 90, 120 and 150 corms per square meter) in the main plot and factorial planting depth (in two levels of 15±2 and 25±2 cm from the soil surface) and corm weight (in two Levels 4± 1 and 8 ± 1 gr) were located in the subplot. The results showed that increasing the density from 60 to 150 corms per square meter caused a significant increase in flower number, flower fresh weight and stigma dry weight, number of plants, number of leaves per plant, average length of a leaf and total leaf length per square meter. Accordingly, increasing the weight of coriander from 4 to 8 gr significantly increases flower number, flower fresh weight, stigma dry weight, number of plants, number of leaves per plant, average length of a leaf, total leaf length per square meter and total Leaf length per plant in the first and second years and reduced flower number, flower fresh weight and stigma dry weight in the third year. The results also showed that increasing the planting depth from 15 to 25 cm caused a significant decrease in all studied traits of saffron. The effect of dual and triple interactions on the studied traits was mainly significant. Overall, the results showed that the use of larger mother corms has a relative priority only in the early years and the importance of its effect decreases with increasing farm age. Based on this, it seems that it is possible to have a different strateg and with a combination of less depth and especially more density to compensate for the effect of corm weight and achieved more overall performance.

To investigating the effect of superabsorbent polymer application on agronomic properties and forage yield of alfalfa under different moisture conditions, a split plots experiment was conducted based on a randomized complete block design with three replicas, in the year 2014-2017. Treatments were irrigation in three levels including included at three levels (no irrigation, water deficit (supplemental) and normal) and super absorbents including 0, 50,100, and 150 Kg/h.There was a significant difference between irrigation treatments in terms of the effect on all studied traits except for the leaf area index, while the difference between superabsorbent levels was significant on all studied traits. Results showed that no irrigation treatment decreased the number of leaves per stem, leaf weight, and leaf area index and by 21.81, 21.18 and 10.86 percent compared with normal irrigation, also the application of 150 kg ha-1 superabsorbent increased the amount of these traits by 22.09 and 18.96 and 17.09 percent respectively. In the present study, water deficit (supplemental) treatment with the application of 150 kg/ha had the highest plant height (73.05 cm), dry forage yield (0.31kg/m2), and crude percent protein (14.58%). The results also showed that the difference between the treatment applications of 100 and 150 kg / ha of superabsorbent in rainfed conditions with control treatment (not using superabsorbent) in normal irrigation conditions was not significant in terms of dry forage yield. Therefore, the use of superabsorbent in different humidity conditions can be a suitable solution to increase the quantitative and qualitative of forage yield in alfalfa

Due to hot and dry climates of South Khorasan province, it is quite vital to choose the suitable crop and planting date. In this condition, pearl millet nutrifeed hybrid (Pennisetum americanum var. nutrifeed) can be a valuable forage in rotation with other plants. This experiment is carried out in 2017-2018 in strip split plots design in time in Azad University research field, Birjand. The treatments include 4 sowing dates (April 8, April 28, May 18, and June 7), 3 irrigation regimes (providing 100%, 75%, and 50% of the plant’s water needs based on the plant potential evatranspiration), and two cuttings in a completely random blocks design with three replications. The highest water use efficiency is observed when providing 50% of water needs on April 8, along with the first and second cuttings. Following the delay in planting date from April 8 to June 7, the forage dry matter yield of millet decreases by 24.4% when it is supplied with 100% of its water needs. This decrease is 24.2 and 46.9, in case of supplying 75% and 50% of water needs, respectively. Therefore, by supplying 75% of pearl millet water needs and planting it on April 8, with a 25% reserve of water consumption, the dry matter yield is acceptable.

To estimate genetic parameters of agronomic traits in tobacco, six oriental-type tobacco varieties were crossed based on diallel mating system without reciprocals in 2013. F1 populations and six parental lines were planted using randomized complete block design with three replications in 2014 at research field of Urmia Tobacco Research Center, Urmia, Iran. Some charectristics including number of leaves, leaf length and width, plant height, stem diameter, internodes length, fresh leaf and dry weight were measured and analyzed using Griffing method II and mixed effect model B. Analysis of variance revealed significant differences (P≤0.01) between varieties for plant height, leaf number and fresh weight and for leaf dry weight (P≤0.05). General combining ability of varieties for all aforementioned traits was significant at the 1% probability level. Specific combining ability was also significant at the 1% probbaility level for plant height, leaf number and fresh weight. Both additive and non-additive (dominance) gene effects were involved in controlling of plant height, leaf number and fresh weight, however, additive gene effect controlled leaf dry weight. In general, the ratio of GCA to SCA was significant for all of the studied traits except leaf fresh weight which emphasizes the importance of additive effect in inheritance of this trait.

In order to evaluate the effect of drought stress on the some morphological characteristics, grain yield and oil yield of safflower, an experiment conducted as split plot arrangement based on RCBD design with three replications at the Research Station of Shahrekord University. Main factor include four levels of drought stress (irrigation after 50, 80, 130, and 180 mm evaporation from evaporation pan of class A) and sub factor include four levels of humic acid (0, 1, 3, and 6 lit/ha) were considered. some Agronomic characteristics such as plant height, sub branch per plant, stem diameter, leaf number per plant, grain yield and oil yield were evaluated. Drought stress and foliar application of humic acid contributed the above mentioned traits. Based on the mean comparison test, drought stress significantly decreased and foliar application of humic acid increased the traits of include plant height, sub branch per plant, stem diameter, leaf number per plant, grain yield and oil yield. The highest grain and oil yields were 1687 and 393.7 kg / ha respectively in irrigation after 50 mm evaporation. Maximum amount of humic acid solution was 6 liters per hectare, which increased grain yield (9%) and oil yield (20%) than control treatment. Based on the results of this experiment and due to the positive effects of humic acid sprayed on safflower plants, recommended in case of risk of drought stress during the growing season of plants, the positive characteristics of organic matter to increase the vegetative and reproductive growth of safflower given more attention.

In order to find suitable ratio of chemical fertilizer and compost, to increase economic yield of onion, a study was carried out at the Malekan Agricultural Farm and Natural Resources Research and Education Station in 2013. The experiment was done in split plot using RCBD with three replications. Fertilizers (A) were asseigned to main plots with six levels (recommended dosage of chemical fertilizers as control (a1), ¾ of the control 4 ton ha-1 of compost (a2), ½ of the control 8 ton ha-1 compost (a3), ¼ of the control 12 ton ha-1 compost (a4) and the compost alone (16 and 20 ton ha-1) (a5 and a6)) and cultivars to subplots with five levels , (B) (Zanjan Qoli Qissa (b1) and Red Azarshahr (b2)). Red Azarshahr was superior to Qoli Qissa in all traits. Fertilizer levels had significant effects on all traits, except number of edible layers, and a1 was highest amount in these traits compared to other fertilizer rates. The interaction of fertilizer × cultivar was not significant in all traits. Combined use of chemical fertilizers and compost had significant positive effect on vegetative traits, bulb diameter, yield per plant and total yield as compared to that of using compost alone. Using ¾ a1 and ½ a1 along with the rate of 4 and 8 t.ha-1 (a2 anda3) of compost had no significant decreasing effect on bulb weight per plant and yield as compared with chemical fertilizer application alone (a1). Thus use of ¾ the control treatment 4 ton ha-1 of compost (a2) and ½ of the control treatment 8 ton ha-1 of compost (a3) can be recommended to the region.

In order to evaluate the effect of humic acid application on agronomic characteristics of some varieties of clover (Trifolium sp.), a field experiment was conducted as factorial based on randomized complete block design with three replicates at Research Field of Faculty of Agriculture, Shahr-e-Kord University, Shahr-e-Kord, Iran in 2013. Three varieties of clover (Bersim, Haftchin (Persian) and Kermanshahi) were considered as the first factor and three levels of humic acid applications [control (without humic acid), 5 and 10 lha-1] as the second factors. Results showed that shoot dry weight, dry weight per plant, root and shoot dry weight per plant, plant height, number of leaves and stem diameter were affected by interaction effect of variety×humic acid. First and Second time of harvest had 57% and 43% of the most values of treatments, respectively. Haftchin and Kermanshahi varieties had the highest and Bersim had the lowest values of the treatments. Humic acid with 10 l ha-1 produced the highest values of measured treatments. In general, application of 10 liter humic acid per ha produced the highest values of shoot dry weight by 3410 and 3800 kg ha-1 in Kermanshahi and Haftchin varieties, respectively. Bersim produced the lowest value of shoot dry weight by 686 kg ha-1.

In terms of production and area under cultivation, wheat is the most important crop in Iran. Weeds problem is possibly the mostserious agricultural problems in the wheat growing regions of the world (Kafi et al., 2005). Rye as an annual plant with long stems is frequently seen as weed in wheat fields around our country (Krimi, 2004). Low environmental demands and allelopathic ability of rye accompanied with similar morphology and life cycle to wheat has increased its stability and occupied area in winter wheat fields (Pester et al., 2000). Competition is one of key issues in ecophysiological debates of plant communities. In competition as a type of Interference, weeds compete for light, water and nutrient resources with neighbor crops and thereby affect growth, development and yield of them (Evans et al., 2003). Considering the severe restriction of water resources in most regions of our country, drought stress is the most important stress, affecting crops (Kafi et al., 2009). Both resource availability and environmental conditions affect the result of a competition. Weed competition for water decreases soil water content which could finally causes water stress and reduces weed growth and crop yield. There are few studies about mechanisms of competition for water. Most of these studies have been implemented under controlled conditions. Nevertheless, these studies have led to an insight intothese possible mechanisms of competition for water (Zand et al., 2004).
In order to study the effect of inter and intra-species competition on morphological and growth characteristics of wheat (Triticum aesativum L.)and rye (Secale cereale L.)under drought stress conditions, a pot experiment was conducted in the greenhouse of college of Agriculture at University of Birjand in 2012. The experiment had factorial arrangement based on completely randomized design with three replications. The factors were wheat density (0, 8, 16, 24 plants/pot), rye density (0, 2, 4, 6 plants/pot) and drought stress (irrigation at 20 and 60% moisture depletion of field capacity). Number of leaves and their SPAD index in wheat and rye were measured at the time of spikes emergence of wheat, while plant height, peduncle and cluster length and stem diameter of wheat were measured at 95 days after planting (the end of the growing period).
Results showed when density of wheat and rye increased, height (maximum of 23.51% and 13.39% in wheat and 24.45% and 6.56% in rye respectively), leaf numbers (35.80% and 30.73% in wheat and 71.37% and 31.71% in rye respectively) and SPAD (12% and 11.38% in wheat and 13.75% and 0.38% in rye respectively) were significantly decreased. Drought stress also significantly decreased the height and leaf number of wheat (17.58% and 8.48% respectively) and rye (7.64% and 26.75% respectively) and significantly increased the SPAD index of wheat and rye (20% and 7.78%, respectively). Increasing of drought stress however had not effect on cluster length, significantly decreased the peduncle length (26.03%) and stem diameter (3.49%). When the rye and wheat density increased, length of wheat cluster (maximum of 13.70% and 24.21% respectively), length of wheat peduncle (maximum of 17.39% and 22.72% respectively) and wheat stem diameter (maximum of 11.11% and 18% respectively).
Result totally showed that in drought stress conditions, intra specific competition had just significantly affected on SPAD index, but inter specific completion had significantly affected on both SPAD index and leaf number of wheat and height and leaf number of rye. Simultaneous presence of drought stress and plant competition resulted in severe reduction of these traits with a further reduction in wheat compared to rye. Accordingly, in the wheat fields where rye is considered as an important weed, the damage of this weed is even higher when drought stress occurs and therefore, controlling this weed in water limited conditions is of major importance.

To find a quick and reliable method to estimate leaf area in safflower cv 'Local Esfahan', a factorial experiment based on completely randomized block design was conducted with four replicates and two factors included sowing date (5 and 25 April and 18 May) and plant density (15, 40, 65 and 90 pl/m-2). In the present study, leaf area was estimated through leaf number on main stem, node number on main stem, leaf dry weight and stem dry weight by the different regression models. Based on RMSE (root mean squares of error) and R2 (determinant coefficient) estimated for studied models, leaf dry weight was the best independent variable to estimate the leaf area. The relationship between leaf area and leaf dry weight described by a linear model. The values of RMSE varied between 24.39 and 61.35 for different densities and the values of R2 was higher than 0.96. This indicates that model could predict leaf area by leaf dry weight. It was found no significant difference between the slopes of linear model fitted on leaf area data against leaf dry weight. Therefore, a general model was fitted on these data using all densities and the values of the a and b coefficients were estimated as 9.7 and 108.7, respectively.

Holy Basil is a perennial shrub plant that belongs to Lamiaceae family. Aerial parts of this plant have been used in food, pharmaceuticals, cosmetics and perfumery industries. Leaves of this plant contain 0.5-1.5% essential oil and main oil components are eugenol, methyl eugenol, carvacrol, estragol, and eucalyptol. In order to evaluate the effect of foliar application of zinc fertilizer on morphological traits of holy basil, an experiment was conducted in research farm of Department of Horticultural Science, Shahid Chamran University of Ahvaz based on randomized complete block design with six treatments and three replications. The treatments were nano zinc chelate (0, 0.5, 1 and 1.5 gr.lit-1) and zinc solfate (1 and 1.5 gr.lit-1) fertilizers. Foliar application of fertilizer was done at six or eight leaf stage and was repeated with an interval of 15 days until the end of the study. Morphological traits includingplant height, branches number, leaf number, leaf size (length and width), leaf area, stem diameter, main inflorescence length, inflorescence number, fresh and dry weights of leave, stem and aerial parts were measured at full bloom stage. The results showed that the effect of foliar application of zinc fertilizers on all measuredmorphological traits of holy basil was significant (p≥0.01). The highest and lowest values of mentioned traits were obtained in plant sprayed with 1.5 gr.lit-1 nano zinc chelate and control, respectively. Overall, given the non significant difference between 1 and 1.5 gr.lit-1 treatments, to increase morphological traits of holy basil, foliar application of nano zinc chelate with 1gr.lit-1 is recommended.

In order to investigate the effect of water deficit on yield and morphological characteristics of four alfalfa cultivars an experiment was conducted as a split plot in randomized complete block design with 3 replications in Agriculture Research Center of Khuzestan, Ahwaz, Iran, during 201l-2012. Main plots included irrigation regimes (normal irrigation, irrigation at 50% available water content (AWC) depletion, 65% AWC depletion and 80% AWC depletion) and subplots were 4 cultivars of alfalfa (Baghdadi, Mesasirsa, Yazdi and Hamedani). The result of 5 cuttings showed that maximum hay forage yield was achieved under normal irrigation in all cultivars. The Baghdadi cultivar produced the highest hay yield at all irrigation treatments, though the hay yield decreased with delay in irrigation. The leaf/stem ratio increased by 22 percent when the cultivars where subjected to 50% AWC depletion. Stem height, LAI and the weight of single stem were decreased by delay in irrigation. Specific leaf area (SLA) decreased in all cultivars due to water deficit, though the extent of the decrease was greater for Baghdadi cultivar. The water deficit affected stem number in a cultivar-specific manner as it increased in Baghdadi and Mesasirsa cultivars and decreased in other cultivars. The Baghdadi and Mesasirsa appeared to be the most tolerant cultivars in Khuzestan conditions.

In order to determine the effect of plant density on yield and yield components of four genotypes of sunflower an experiment was conducted in Research Farm of Zabol University in 2011. The statistical design was split plot in randomized complete block with three replications. Four plant densities (7, 9.5, 12 and 14.5 plant/m2) and four genotypes of sunflower (Hysuun33, Alester, CMS-R43 and Chernianca) were considered. The results showed that there was a significant difference between cultivars on seed yield, 1000 grain weight, plant height, number of seed on head and number of leaf. Also effect of different densities was significant on seed yield, head diameter, plant height, number of seed on head and number of leaf. Interaction effect of plant density and cultivar was significant on plant height. Plant height of Alester, Hysuun33 and CMS-R43 cultivars enhanced with increasing number of plant, but plant height of Chernianca cultivar had not significant variation under different plant density. Also, interaction effect of cultivars and plant densities was significant on 1000 grain weight. In general, Hysuun33 with average grain yield of 6500 kg/ha and Chernianca with average grain yield of 5240 kg/ha and suitable plant height was suggested for Sistan region. Also 14.5 plant/m2 density with average grain yield of 6903 kg/ha was suitable for this condition.

To evaluate the yield and nitrate concentration in five Iranian spinach landraces, a study was conducted in 2011 using a randomized complete block design with four replications at Isfahan Agricultural and Natural Resources Research Station. In this field experiment, the evaluated landraces included spiny seed Varamin, Varamin leafy, Shahreza, Najaf Abad and Kashan. Varamin spiny seed landrace with 47830 kg ha-1 produced the maximum yield among the landraces. Greater numbers of leaves (more than 20 leaves) and lateral branches (more than 3.5) in the spiny seeds Varamin, Varamin leafy, and Kashan was the reason behind their higher yield. In all five landraces tested, nitrate concentration in the middle leaves of the plant was higher than the upper or lower leaves, though there was no significant difference between the upper and lower leaves in terms of nitrate content. Leaf nitrate concentration in spiny seed Varamin landrace was the highest (1380 ppm based on fresh weight) but there was no significant difference between the amounts of nitrate in this landrace and other landraces (except Kashan landrace). The results showed that the spiny seed Varamin landrace, with acceptable yield and nitrate content can be used as a substitute for genotypes that are common in Isfahan province.

During cold seasons cucumber growth in open air encounters chilling damages. Plastic tunnels provide suitable heat environment to grow cucumber. The aim of this research is to evaluate cucumber phonological stages and leaf area expansion within three different plastic tunnel microclimates to moderate air temperatures and air humidity. Three microclimates of (1) completely closed plastic tunnel (MC), (2) perforated plastic tunnel (MP10), with 100 holes (10 mm in diameter) per m2, and (3) perforated plastic tunnel (MP15), with 100 holes (15 mm in diameter) per m2, as experimental treatments, were employed using a complete block design with tree replications. By employing SNK post-hocthe results showed a significant difference for growth degree-days and leaf area expansion between tunnels. Within MC tunnel phonological stages always were occurred ahead of other treatments. Cucumber leaf numbers and second lateral branches within MC were significantly higher than perforated plastic ones. Late in the season leaf area of MP10 reached MCs. In conclusion, MP10 microclimate with relevant microclimate condition could be a good option for early cucumber production.

Prediction of leaf area is essential in crop simulation models. The objective of this study was to find relationships between leaf area (LA) cm2.plant-1 and numbers of leaves on main stem (NLMS), leaf dry weight (LDW) g.plant-1, total dry weight of vegetative organs (leaf and stem) (TDWV) g.plant-1 and plant height (PH) cm, in wheat. For this purpose, an experiment was conducted using seven wheat cultivars including two durum wheat (Triticum durum) cultivars (Arya and Dena) and five bread wheat (Triticum aestivum L.) cultivars (Darya, Kuhdasht, Shiroudi, Tajan and Zagros) under irrigated and rainfed conditions at research farm of the Gorgan University of Agricultural and Natural Resources Sciences, Gorgan, Iran, in 2008-2009 cropping season. The experimental design was randomized complete block with four replications. Sampling was performed during the whole growing season. In each sampling; LA, NLMS, LDW, TDWV and PH, were measured and recorded. Segmented nonlinear regression model was used to describe allometric relationships between LA and the vegetative characteristics. Results showed that there was no significant difference between cultivars and the two conditions in respect to coefficients of allometric relationships. Therefore, one equation was used for all cultivars under both conditions. Significant relationships were found between LA and NLMS (R2 = 0.92), LDW (R2 = 0.96), TDWV (R2 = 0.95) and PH (R2 = 0.91). These equations can be used in simulation models of wheat as well as for the fast and easy estimation of leaf area, especially where there is no necessary equipments available.