مجله تولید گیاهان زراعی
سال پانزدهم شماره 1 (بهار 1401)

Intercropping is an important strategy for enhancing the sustainability of agriculture in the world by increasing food production and land use per unit area. Intercropping, which is defined as growing two or more species simultaneously in the same field during a growing season, is considered as an important strategy in developing sustainable production systems. In most cases, one of the plants introduced in intercropping is a plant from the legumes family. Chickpea is a plant that plays an important role in sustainable agriculture and soil fertility.

In order to evaluation effect of chickpea-barley intercropping on component yield, grain yield and weed control, an experiment was conducted at the Jahad Keshavarzi Shazand Research Station during 2019-2020 growing season. Experiment was conducted as a randomized complete block design with three replications. Different experimental treatment were: 1- chickpea sole cropping without weeding, 2- chickpea sole cropping with weeding, 3- barley sole cropping (normal weed control by farmers), 4- additive intercropping of 100% chickpea + 15% barley, 5- additive intercropping of 100% chickpea + 30% barley, 6- additive intercropping of 100% chickpea + 45% barley, 7- additive intercropping of 100% chickpea + 60% barley and 8- additive intercropping of 100% chickpea + 75% barley. Intercropping systems was evaluated by using land equivalent ratio (LER) index.

The results showed that most of the evaluated properties were affected by experimental treatments. The highest chickpea biological yield and grain yield (334 and 99 g m-2, respectively) belonged to the chickpea sole cropping with weeding treatment. Also, the highest barley biological yield and grain yield (423 and 195 g m-2, respectively) were obtained in its sole cropping treatment. In intercropping treatments, the highest grain yield of chickpea and barley (94 and 190 g m-2, respectively) were obtained in additive intercropping of 100% chickpea + 15% barley and additive intercropping of 100% chickpea + 75% barley treatments, respectively. Also, intercropping treatments significantly reduced the weed density and total dry weight. Thus, all intercropping treatments had less weed density and biomass in comparison to chickpea sole cropping without weeding. The lowest weed density and biomass (7.3 plant per m2 and 60 g m-2, respectively) belonged to the additive intercropping of 100% chickpea + 75% barley treatment. In addition, in all intercropping treatments, the land equivalent ratio and relative value indices were higher than one, which indicates the usefulness of intercropping.

The results of this study showed that, chickpea-barley intercropping systems decreased chickpea grain yield in comparison with sole cropping with weeding treatment but, in general, in the most of the intercropping treatments, was better than their sole cropping and associated with improving economic yield and land use efficiency. In general, it can be said that chickpea and barley intercropping, while better controlling chickpea weeds, has a higher total yield than sole cropping of both chickpea and barley species and increases land use efficiency.

Achievement to accumulate environments potential such as light lead to extend leaf area and increasing in yield and yield components parameters of foxtail millet lines compared to check treatment via improvement of plant height, number of leaf, number of node, panicle length and stem diameter reported by many researchers. Works in the late 1980s demonstrated that yields can be raised two to three-fold by using available improved varieties and appropriate agronomic techniques. But, these findings need to be refined, improved and tested for local climatic, soil and crop conditions.

In order to study of yield, yield component and some morphological and phonological treats of foxtail millet cultivars, a field experiment was conducted across two years at Gonbad Agricultural Research Station. This experiment was laid out in a randomized complete block design in form of split split plot experiment and replicated three times. At this research effects of plant density at three levels (30, 35 and 40 plants m2), planting distance at three levels (40, 50 and 60 cm) and verities of KFM2, KFM5 and Bastan, millets were investigated. Each variety was planted in four lines, the length of planting lines were 10 meters. The seeds were planted in series, and then based of row distance treatments and plant densities of D1, D2 and D3 sparse operation done. For forage yield estimation, after removing borders, 4 m2 from middle rows of end of plot harvested. For measurements of agronomical and morphological treats, 10 bushes randomly sampled. Data were analyzed using SAS software.

The results showed that; with decreasing plant density, 1000-seed weight increased from 2.68 to 3.3. Within variety KFM5 line had the most 1000-seed weight (3.29 gr). The lowest plant density had the highest panicle length. And the most number of grain at panicle (3560) and grain yield (2.78 ton ha-1) obtained from plant density of 350 plant ha-1. The 50 cm distance row had the most number of grain at panicle 3456).

Overall findings showed that; plant density of 350000 plant ha-1 with yield of 2.70 ton ha-1 and 7.7 percent increasing, was better than check treatment. Mean comparison of cultivars showed; KFM5 variety with 2.71 ton ha-1 and 14.02 percent increasing, was optional variety. Meanwhile, the KFM5 which is early reaching variety, because of open cluster panicle don’t effected by disease.

Optimum planting date is very important and it is one of the important factors for maximizing yield production. Although, chemical fertilizers provide plant nutrients faster and more effective, but in order to increase the quality of products, especially the medicinal and aromatic plants, the use of organic fertilizers is better than chemical fertilizers. Organic fertilizers cause decreasing in bulk density and increasing water retention in the soil. Manure is one of the organic fertilizer sources which its application is conventional in sustainable management system of the soil. So, the present study was carried out in order to investigate effects of planting date and application of manure, chemical fertilizer on some morpho-physiological characteristics and essential oil of Moldavian Balm.

A split plot experiment was conducted in a randomized complete block design with three replications at the research farm of Shahrekord University in 2018. In this experiment, the main factor was 3 levels of planting dates: 20 April, 12 May and 3 June, while 6 levels of manure application: 1) no amended fertilizer 2) 25% urea + 75% manure 3) 50% urea + 50% manure 4) 75% urea + 25% manure 5) 100% urea and 6) 100% manure, were used as subplot factors.

The results showed that planting date and fertilizer had a significant effect on all the characteristics measured at this experiment. The interaction of planting date and different fertilizer treatments on all the measured traits except the stem diameter, length of main inflorescence and chlorophyll a was significant. The maximum stem diameter was related to 12 May while the maximum length of main inflorescence and chlorophyll a was belonged to the planting date of 3 June. The maximum amount of leaf dry weight was derived from 12 May + 100% manure, the maximum biological yield was obtained from 3 June + 100% manure, the maximum essential oil percentage from 20 April and 3 June + 100% manure and the maximum chlorophyll (b, total) and essential oil yield from planting date of 3 June and 100% manure application, were obtained.

Based on the results obtained at this experiment, it can be concluded that the 100% manure caused increasing in some morpho-physiological characteristics of Moldavian balm. It seems that manure due to water holding capacity in the soil could have this positive effect on traits. So, since the main reason of medicinal plant cultivation is obtaining their essential oil, so it is recommended that in similar condition, Dracocephalum moldavica L. is cultivated on 3 June with application of 100% manure.

Chickpea is the third most important cereal crop in the world after beans and peas. European scientists found that studying 542 plant species in 26 European countries, including 125,000 time series, found that in 78% of the time between 1971 and 2000, the rate of development increased due to rising temperatures and shorter stages. The shortening of the growth period caused by the increase in temperature in most crops reduces yield because it absorbs less radiation and has less time for dry matter accumulation. The purpose of this study was to identify the effects of climate change on phenological traits of chickpea in Gonbad city in order to adapt and improve yield for future conditions.Materials and MethodsFirst, meteorological data from the Dome Synoptic Weather Station from 1993 to 2017, including daily data on maximum and minimum temperatures, sunshine hours and rainfall, and then processed and converted to DOY using the Srad -calc program (Soltani & Sinkler, 2012) Solar radiation was calculated based on sunny hours and days of the year. Then, new changes were made to the meteorological data based on climate change scenarios. The SSM-iLegume-Chickpea model was implemented for both rain and water conditions and each scenario. Planting type was selected according to the climatic conditions of the region, autumn and the type of free cultivar. Simulations For each rainfed and irrigated condition, three different planting dates (December, January and February) were selected and simulations were performed for 25 years (1993-2017). Results Planting date and climate change scenarios were significant at 1% level for all phenological traits in both rainfed and irrigated conditions, while the interaction effects of planting date and climate change except day to emergence were significant at 1% level. As the temperature rises in the future climate, the length of the phenological stages, ranging from day to flowering, day to pod start, day to physiological maturity, and day to harvest maturity will be reduced compared to normal conditions. Maximum decrease in phenology length was related to increase in temperature of 6°C and combined effects of doubling Co2 concentration, two percent decrease in precipitation and increase of 6°C under normal conditions, and minimum decrease in temperature increase scenario by 2°C. Co2 is a two percent decrease in recipitation and an increase of two degrees Celsius in both rainfed and irrigated conditions. Therefore, due to unchanged phenological stages under Co2 doubling scenarios and 2% reduction in rainfall compared to normal conditions, and reduction in phenological stages under the influence of temperature rise scenarios and similarity of the results of the temperature rise scenarios alone compared to the combined effects of Co2 doubling and 2% decrease in precipitation and an increase in temperature can be deduced that only an increase in temperature reduces the length of the phenological stages.ConclusionSimulation results in Gonbad city showed that increasing Co2 concentration in both rainfed and irrigated conditions and different planting dates had no effect on the phenological stages of chickpea but increasing temperature would significantly decrease the chickpea growth period, although this decrease in the length of chickpea growth is greater in the vegetative growth stage. As a result, the chickpea plant enters the reproductive stage faster, enjoys better temperature and humidity conditions in the reproductive stages, and causes premature and eventually evaporation of drought and late-season heat, and ultimately increases yield under conditions that will be dry. But delay in chickpea planting will shorten the chickpea growth period, depletion of available resources such as radiation, optimum humidity and temperature, dealing with end-season heat and drought, and ultimately yield loss.

Closing the gap between actual yields which are currently obtained from the fields (actual field yields) and the maximum yields that can be achieved under favorable management conditions (attainable yield) is one of the most critical problems in crop production in Iran and the world. Quantifying the yield gap and identifying its primary causes for this purpose can be a key and promising strategy to increase production per unit area and to achieve food security. Meanwhile, considering the importance of oilseeds like soybean [Glycine max (L.) Merril] in the global economy and the need for edible oils and vegetable proteins, estimating and identifying the causes of the yield gap, while increasing production, it can improve land use and labor efficiency, and leads to costs saving and sustainable production. In this way, a survey study was conducted in 2019 to identify and determine the share of each of the managerial factors affecting the soybean yield gap in 301 farms in Mazandaran province.

In the present survey, CPA method was used to investigate the decision-making factors which limit soybean yield and to estimate its yield gap in 13 soybean cultivated cities of Mazandaran province. For this purpose, all information relevant to crop management, from seedbed preparation to harvesting, was gathered through interviews with 301 soybean producers. These management factors included items such as use or non-use of a plow, number of secondary tillage, planting method, field area, previous crop, the used cultivar, seed rate and its preparation site, inoculation/non-inoculation of seeds with N-fixing bacteria, type and the amount of fertilizers, type, amount, and number of herbicides, fungicides, and insecticides usages, number of irrigations and the amount of used water, irrigation type and harvesting methods. Field monitoring data included 81 quantitative and qualitative crop management variables that the relationship between all these variables and actual field yields was analyzed using stepwise regression in SAS (v9.1) software. In the end, the contribution of each limiting factor to the creation of a yield gap was determined using the resulting production function and management parameters values.

The findings of this study revealed that of the 81 studied management variables, the final production function with 10 independent variables was selected. These variables included the sari variety (J.K-695), previous crop (faba bean), use the row planter, number of secondary tillage, sulfur rate, application of herbicide, KCl, and (NH4)2HPO4 fertilizers, sprinkler irrigation system, and surface irrigation, which were identified as the main limiting factors for soybean yield in Mazandaran province. Based on the difference between the average actual yield recorded on farms (2464.97 kg ha-1) and the maximum attainable yield (6028.66 kg ha-1) predicted by the production function, the yield gap was 3563.70 kg ha-1, which is three factors including sulfur rate, previous crop (faba bean) and sprinkler irrigation system with the values of 873.87, 620.49 and 546.33 kg ha-1, respectively, had the highest share (24.52, 17.41 and 15.33%, respectively) in of the soybean yield gap.

According to the predicted attainable yield which derived from actual farm data it seems that adoption of proper crop managements such as using sulfur fertilizer resources appropriate to plant needs, an appropriate crop rotation and selection of plants suitable for rotation, providing facilities and modernization of agricultural machinery, and develop and promote new irrigation can reduce this gap (59%) and significantly improve soybean yield in Mazandaran province.

Wheat is one of the most important plant sources for humans and drought is one of the most important abiotic limiting factors that affects the growth and development of wheat. Exogenous applications of plant growth regulators (PGRs) may be useful for decreasing the harmful effects of drought stress on wheat, therefore, this research was laid out to investigate the effect of foliar sprays of gibberellin, cytokinin and cycocel on root and shoot characteristics, secondry metabolites and yield of two wheat cultivars under different moisture regimes.

The present study was conducted as two separate designs each with three replications in hydroponic and field conditions in the University of Kurdistan, in 2015-2016. Hydroponics experiment was conducted as factorial based on randomized complete block design. The factors were the moisture levels (control, -4, -8 bar), two wheat cultivar (Sirvan and Homa) and four levels PGR foliar application including water as control, gibberellin (100 µm), cytokinin (100 µm) and cycocel (3 grlit-1). Field experiment was carried out as split-split based on randomized complete block design. The irrigation treatment at four levels (dryland, one time irrigation, two times irrigation and three times irrigation) as the main plots, two wheat cultivars (Sirvan and Homa) as sub-plots and the plant growth regulators foliar application listed above as the sub-sub plots were considered. Root and shoot dry weight and root to shoot dry weight ratio, root volume, root length, Plant height, total phenol, flavonoids, anthocyanins content and yield were determined.

In the hydroponics experiment, root traits increased in the -4 bar as compared with the control while plant weight and height were decreased in the -4 and -8 bar. In most treatments, the highest ratio of root to shoot weight was obtained in drought stress. Homa cultivar was superior to Sirvan cultivar in terms of all traits. Foliar application treatments hadn't a significant influence on root length and plant height, but the application of PGRs especially cycocel, increased the root and seedling weight and root volume. In field experiments, the results showed that the amount of phenol, flavonoids, and anthocyanins in dryland conditions was higher than other irrigation treatments. Among growth regulators, gibberellin increased flavonoids (13.2%), and cycocel increased anthocyanins content (17.3%) Compared to the control. The results also showed that, the highest grain yield in both cultivar was obtained under three times irrigation condition and cytokinin and cycocel consumption.

It seems that cycocel can increase the resistance of wheat to drought stress by improving the root characteristics and increasing anthocyanin content. In both cultivars, irrigation increased grain yield compared to rainfed conditions and the use of growth regulators, especially cytokinin and cycocel, increased yield compared to the control. Therefore, based on the results of this experiment, applying even one stage of irrigation in water limitation conditions and the use of cytokinin and cycocel in water availability conditions could be recommended to enhance grain yield under the region climatic condition.

Due to drought, water crisis and increasing soil salinity in Jiroft region in recent years, it seems necessary to cultivate alternative crops for the cold season with low water requirements, high economic efficiency and compatibility with the region and short growth period. Quinoa (Chenopodium quinoa Willd.) is a good choice for this due to its low water requirement and high salinity resistance. Therefore, this study aimed to investigate the protein and saponin contents as well as yield and yield components of quinoa genotypes during autumn and winter cultivation.

This experiment was performed as a split plot in the form of a randomized complete block design with 4 replications, in the research farm and laboratory of the Agricultural Research and Training Center and Natural Resources in the south of Kerman province in the two cropping years of 2018-2019. Planting date (autumn and winter) was the main factor and the genotypes Titicaca, Redcarina, Gza1, Q12, Q18, Q21, Q22, Q26, Q29, Q31 were the second factors. In this experiment, traits such as stem length, the length of growth period, seed protein and saponin contents, 1000-seed weight and grain yield were determined.

Combined analysis of variance of the data showed that the traits measured in this experiment (stem length, length of growth period, percentage of seed protein and saponin) were significantly affected by genotype, planting date and their interactions. Inflorescence length was only significantly affected by genotype. Stem length was very different in autumn and winter cultivation so that in autumn cultivation the highest stem length occurred in Q22 and Q12 genotypes but in winter cultivation the highest stem length was related to Q26 and Q29 genotypes. In all studied genotypes, the percentage of saponin and protein in autumn cultivation was less than winter cultivation, the range of changes in grain saponin and protein percentage was between 4.52 to 5.56 and 10.78-13.89 percent, respectively. Also, grain yield and 1000-seed weight of quinoa were significantly affected by genotype, planting date and their interactions. The range of grain yield changes varied between 1.91 (autumn cultivation treatment and GZA1 genotype) to 3.99 tons per hectare (autumn cultivation treatment Q12).

The results of this study also showed that it is possible to cultivate this crop twice a year in Jiroft region, provided that appropriate cultivars are used. Therefore, Q12 and Q31 cultivars are recommended for autumn cultivation while Q29 and Q26 cultivars are recommended for winter cultivation.

Golestan province is one of the 8 provinces exposed to drought in the country. For this reason, it was banned the cultivation of rice in Golestan province. On the other hand, in recent years, the tendency to cultivate rice has increased due to the greater economic benefits of this crop compared to other crops such as soybeans in this province. It seems that the first step to develop Aerobic field rice cultivation is to assess the environmental variables and land potential with agro-ecological requirements of this type of cultivation system. Therefore, changing the method of rice cultivation from lowland to aerobic system can be considered in maintaining the stability of rice production in Golestan. Considering of limitation of water resources in country especially in Golestan province, nowadays introduce a new agricultural system with low water consumption is very important. One of these systems is aerobic rice cropping. The aim of this study was to assess the land use suitability of a part of Golestan province (Aq-Qala County) for aerobic rice cropping development, using environmental variables assessment and spatial analysis in 2019.

First, the agroecological requirements of an aerobic rice system determined using scientific sources and referring to pattern fields. Then, thematic maps of climate, topography, soil and water resources were provided in ArcGIS media. In continue, all layers overlaid based on Simple Limitation Method (SLM) and Boolean Logic. Finally, map of feasibility of aerobic rice cropping development for croplands of Aq-Qala County as a pilot region provided and classified.

Feasibility results showed that only lands of south in Aq-Qala county had the suitable degree for aerobic rice cropping development (21,003.63 ha). According to land use suitable map, land capability degree was reduced from south to north of county. The marginally class (S3) had the highest area than other classes (36,965.61 ha). Results of fitness of Aq-Qala croplands with agroecological requirements of an aerobic rice system showed that about 26.73 percent of region was unsuitable for performance of this system. This region was located in the north of county, from east to east and found in Atrak watershed. Also, results of land use suitability according to Boolean Logic showed that 5.3 percent of region was suitable for aerobic rice cropping development, but 94.62 percent of croplands had the unsuitable degree (NS).

Generally, limitation variables of NS zone based on both of applied models were involved annual rain <300 mm, soil EC>7 dS/m, low amount of organic matter, high EC of surface water resources, unsuitable status of surface and ground water resources, SAR <12 of water resources and unsuitable pH.

Obtaining genetic information on how to control traits and becoming aware of the genetic potential of breeding populations is the most important prerequisite for success in cultivar breeding projects. Graphic analysis of the data obtained from the diallel design by means of the (GGE biplot) biplot method allows the breeders to obtain a larger volume of comprehensive genetic information with higher resolution than the conventional methods. The aim of this study was to obtain genetic information and create various breeding materials with high potential in terms of grain yield and its components in bread wheat.

This study started with identifying and collecting 10 bread wheat cultivars with various and complementary characteristics in terms of grain yield and other related and important economic and agronomic traits. The crossing of parental cultivars and the evaluation of the progeny diallel crosses were carried out in 2018 and 2019, respectively. The progenies of the 10×10 full diallel were studied in a randomized complete block design with three replications and examined for grain yield, 1000-seed weight, plant height, spike length, number of seeds per spike and spike weight.

Based on the results of analysis of variance, the mean squares of genotypes were significant for all traits (α≤ 1%), indicating the existence of sufficient diversity among the studied genotypes. Effects of general combining ability for the parents on plant height, spike length, 1000-seed weight and grain yield and effects of specific combining ability for crosses on plant height, spike length, number of seeds per spike and grain yield was significant. Also, the difference of reciprocal crosses was significant for plant height, spike length, number of seeds per spike and 1000-seed weight. The results of bioplot analysis showed that Ehsan had the highest general combining ability among the parents for grain yield, 1000-seed weight, plant height, spike length. Accordingly, the highest specific combining ability for grain yield was observed between Ehsan against both Gonbad and Shoush cultivars. Also, the spesific combining ability of Ehsan in crosses to Kalateh, Barat, Shoush, Sirvan and Gonbad cultivars had the highest value for 1000-seed weight, plant height, spike length and spike weight. The highest narrow sense heritability was observed for spike length however, for plant height, number of seeds per spike, grain yield, 100-seed weight and flag leaf area, the narrow sense heritability was low.

In general, cultivars Ehsan and Gonbad were able to transfer most of the characteristics to their offspring, therefore they can be used in breeding programs to improve grain yield and yield components in bread wheat. Due to the greater importance of the dominance component in control of grain yield and its components, can be used to determine suitable parents for crossbreeding and production of new varieties.

Most saline areas where plants do not have suitable conditions for growth are exposed to soil erosion and desertification. Plant species that are highly resistant to drought and salinity can be cultivated in these areas. These plants can prevent soil erosion. Therefore, the main purpose of this study was to investigate the effect of planting date and salinity on the biological stability of Salicornia iranica against fine dust stress.

This experiment was performed as a factorial split in a randomized complete block design with three replications during the growing season 2019-2020 in the research farm of the college of Aburaihan, University of Tehran, Pakdasht, Iran. Factors tested included: three planting dates: April 1, April 6, April 31 as the main plots, fine dust agent at three levels (control (without applying fine dust), spreading fine dust on the plant for 5 days and 10 days), to Sub-plots were considered in two separate areas: saline area (area one with the salinity of 7.55 dS / m) and non-saline area (area two with the salinity of 2.8 dS / m). The mass used in this experiment was Yazd mass.

The results showed that fine dust treatment and planting date had a significant effect on all traits. The highest membrane stability in zones one and two on the date of first planting in the control treatment was obtained with an average of 79 and 78%, respectively. The highest chlorophyll-a in zones one and two were obtained on the date of the second planting in the control treatment (without application of fine dust) with an average of 76.2 and 77.6 mg per leaf fresh weight, respectively. The highest amount of chlorophyll b in zones one and two on the date of the second planting was obtained in the control treatment (without the application of fine dust) with an average of 58 and 59 mg.g-1 fresh weight, respectively. Comparison of the mean data in region one showed that the highest percentage of relative leaf moisture on the first planting date in non-stress conditions (with an average of 81%) and in region two (salinity 2.8) on the second planting date in the control treatment (Without the application of fine dust) with an average of 80%. The highest and lowest heights of the Salicornia plant were on the second planting date in the control treatment (without application of fine dust) in zone one with an average of 60 cm and the second planting date on the third planting date in the ten-day treatment with a mean of 18 cm, respectively. Was obtained The highest wet and dry forage yields were observed in zones one and two on the second planting date in the control treatment (without application of fine dust) with an average of 218, 9.8, and 107, 77 g.plant-1, respectively.

The results showed that Salicornia performed better in saline soil. On the other hand, the study of traits showed that the planting date could increase the resistance of Salicornia to fine dust stress because in the second planting date, the percentage of reduction in all traits was less than the first and third planting dates. Among the agronomic factors, planting time is one of the most important factors determining plant yield. The planting date for each species in a particular area should be considered according to the ambient temperature and soil at the time of planting and also based on the fact that the plant does not interfere with flowering at high temperatures.

Prediction of development periods of crops by mathematical models, especially, time to growth ending is so important in every area. So, as impotence of prediction of phenology, leaf area and time to leaf growth ending, this research performed to introduce and test of Phenology MMS model in environmental conditions of Boukan, prediction of leaf appearance rate, phyllochron in stress condition of drought and to correct coefficient of allometric equations of predicting of leaf area of Corn (cv. Single cross 704) and Sunflower (cv. Shamshiri).

In this research, Phenology MMS evaluated using field data for corn and sunflower . Then time and thermal time needed to leaf growth ending and phyllochron (degree day per leaf) obtained using segmented model in every stress level. So, the best algometric model selected for describing of relation between leaf area and leaf number.ResultsResults showed that the model predicted development periods of corn and sunfloer well and was capable to estimate day and thermal time needed to every special development period in two state: day after sowing and day after emergence. Also, in corn, results released that time to leaf growth ending will occur after reception of 782.9 degree day which equal to 72.3 day after emergence whereas for sunflower time to leaf growth ending will occur after reception of 798.1 degree day which equal to 59.14 day after emergence. On other hands, a leaf will include to plant 3 and 2.06 day after emergence in corn and sunflower respectively. In medium tension, the slope of regression line of leaf number versus thermal time, increased and reached to 0.0285 and 0.033 leaf per degree day in corn and sunflower respectively. Results of predicting of leaf area using exponential segmented models showed that all of models were good in predicting of leaf area index.

As for being acceptable of results of phonological model for prediction of thermal time, leaf number and phyllochron, we advise using of this model in modeling and agronomical studies. So, drought stress can effect on leaf appearance rate and phyllochron value. All of models were good in predicting of leaf area index.ConclusionAs for being acceptable of results of phonological model for prediction of thermal time, leaf number and phyllochron, we advise using of this model in modeling and agronomical studies. So, drought stress can effect on leaf appearance rate and phyllochron value. All of models were good in predicting of leaf area index.