فهرست مطالب عبدالستار دارابی

This experiment was conducted for two years to study post–harves bulb losses of onion genotypes in uncontrolled storage (no heating, cooling and ventilation systems) at Behbahan Agriculture Research Station. Seeds were sown in nursery in early October and seedling transplanted at 2-3 leaf stage. Bulbs were harvested when 50-80% of foliage top had fallen and collapse. The research was performed using split factorial experiment based on RCBD including 120 treatments with 3 replications. Main plot consisted of six bulbs observation in storage (one months after storage with one month interval). Sprayed and non-sprayed plots and ten onion genotypes named Behbahan, padook, Ramhormoz, Iranshahr, Borazjan ,Dorcheh Esfahan, and Kamerei Khomain landraces, Primavera and Texas early grano cultivars and improved population of Behbahan onion were considered  as factorial. Thrips increased bulb weight losses, damage of black mould and total losses. The damage of bulb rotting decreased in non- sprayed plots as compared with sprayed plats. The effect of thrips was not significant on bulb sprouting. The minimum bulb weight losses and damage of black mould were recorded in Primavera cultivar and Behbahan improved population respectively. The lowest bulb rotting was observed in Ramhormoz landrace. The highest bulb sprouting was found in Iranshahr landrace. According to results, Texas early grano cultivar and Dorche Esfahan landrace, showed the maximum and minimum bulb storability respectively.

After potato, watermelon is the most important vegetable that cultivated in Iran. Irrigation is necessary for watermelon cultivation due to its high growth rate, short growth period and high fruit water content (90-92%). In addition high evaporation during growth and development stages and low rainfall in arid and semi-arid area caused that cultivation of watermelon need a lot of water. To minimize drought stress effect on yield of agricultural crop in arid and semi-arid areas, cultivation of drought tolerant cultivars, deficit irrigation practice and grafting of high yielding cultivars onto tolerant rootstocks are recommended. No paper has been published about grafting and deficit irrigation for watermelon cultivation in Khuzestan province yet, therefore present research was conducted to study the effects of these factors on yield, yield components and water use efficiency of grafted watermelon (B32 cultivar) onto pumpkin ‘Cubalt and Ferro’ (Cucurbita maxima × Cucurbita moschata.) and deficit irrigation in nongrafted watermelon.

This study was carried out at Behbehan Agriculture Research Station from 2020 to 2021. The experiment was done as strip plot in randomized complete block design with nine treatments and three replications. Three irrigation regimes, full irrigation, 80% and 60% of full irrigation were considered as vertical strips. Horizontal strips included B32 cultivar grafted onto pumpkin ‘Cobult and Ferro’ rootstocks (Cucurbita maxima × Cucurbita moschata.) and nongrafted B32. Watermelon and pumpkin seeds were planted in greenhouse in 5 and 10 January respectively and watermelon seedlings were grafted onto pumpk in 4 February. Seedlings were transplanted in 24 Feb. and fruits harvested from early to mid-June. Results were analyzed by MSTATC statistical software and comparison of meanes were done using Duncan,s Multiple Range Test at 1% probability level.

Yield, mean fruit weight and water use efficiency in grafted plants were significantly higher than nongrafted plants. Yield and mean fruit weight decreased significantly due to deficit irrigation. The most yield in grafted and nongrafted plants were obtained in full irrigation. The decrease of yield in nongrafted plants applied 80% of full irrigation as compared with full irrigation was not significant. In full irrigation regime the mean yield of grafted plants were significantly higher (50%) than nongrafted plants. The yield of grafted plants applied 80% of full irrigation were higher than nongrafted plants applied full irrigation , however this difference was not significant. Water use efficiency of grafted plants was significantly higher as compared with nongrafted plants. The differences of water use efficiency in grafted plants onto Cobult and Ferro rootstocks applied full irrigation, 80 % and 60% of full irrigation were not significant. In nongrafted plants the most water use efficiency belong to applied 80% of full irrigation. The decrease of water use efficiency in plants applied full irrigation was not significant as compared with this treatment. However the decrease of water use efficiency in plants applied 60% of full irrigation was significant in comparison to plants applied 80% of full irrigation.

grafting of B32 cultivar onto Cobult and Ferro rootstocks and applied full irrigation and 80% of full irrigation were recommended in no water restriction and water shortage conditions respectively for the maximum watermelon production in Khuzestan province.

This research was conducted to compare agro-meteorological indices and yield of short day onion cultivars. The experiment was done in randomized complete block design including 15 cultivars (Seba, Imperateriz, Siroos, 7030, S.V. 4043, X. P. Red, Sweet Ajent, Savana Sweet, Golden I, Primavera, Texas Early White, Texas Early Grano, White Grano, Spidan and Contessa) with four replications at Behbahan Agriculture Research Station, southwest of Iran, for two years (2016-18). Seeds were sown in nursery in early October and seedlings were transplanted in early November. Bulbs were harvested when 50-80% of foliage had senesced and fallen. The differences of growing degree days and helio thermal unit were considerable among cultivars from planting to bulbing stage, however the differences of photo thermal index were not significant among cultivars at this stage. During bulbing and bulb development stage differences of growing degree days, helio thermal unit and photo thermal index were considerable among cultivars. Evaluation the correlation coefficients among yield and agro-meteorological indices during bulbing and bulb development stage suggested significant negative correlation of bulb yield with growing degree days and photo thermal indices. The highest bulb yield, thermal use efficiency and helio thermal unit use efficiency were recorded in Siroos (hybrid cultivar). As the seed price of open–pollinated cultivar is less than the prices of hybrid cultivars and the seed of open-pollinated cultivars could be produced by the growers, therefore, planting of Texas Early Grano (open-pollinated cultivar) is recommended for onion production in Khuzestan province at southwest of Iran.

The onions produced in centeral and northern regions of Iran are consumed in autumn and mid winter, and after that, there is a shortage of onions in the market. This shortage can be eliminated by onion production in mid winter in the southern regions of Iran. Short day, early maturity, tolerance to environmental stresses and high yielding are characters of cultivars, that are recommended for onion production in southern regions of Iran. Although many onion landraces are observed in southern region of Iran, however due to low yielding of these landraces, foreign cultivars such as Texas early grano, Texas early white, Primavera and Saba are cultivated in the most part of these regions. Recommended sowing seed and transplants as well as sets transplanting dates varied from early October to mid September depended on climatic conditions, planting methods, season production and genotypes. Application of Zn-Amino celates (specially methionine-Zn) increased yield, pungency, storability and decreased nitrate accumulation in improved population of Behbahan onion and Primavera cultivar. In intercropping of onion and lettuce as well as fenugreek yield, land equivalent ratio and income equivalent ratio were higher than sole crop. Ramhormoz genotype is relative resistance to thrips. Pendimetalin, Focus, Select, Gallent-Super and Oxyfluorofen herbicides control weeds in onion farms. Resistance inducers can be used as a substitute for fungicide application to control downy mildew in onion. The storability of improved population of Behbahan onion , Texas early grano as well as Seba cultivars are high.

In order to study the effects of direct seeding and transplanting methods on yield and agronomic characters as well as economic benefit in short day onion genotypes an experiment was conducted at Behbahan Agricultural Research Station located in the Southwestern part of Iran from 2014 to 2016. The experiment laid out as factorial based on randomized complete block design with six treatments and four replications. Factor (A) was onion genotypes: Ramhormoz landrace, improved population of Behbahan onion and Primavera cultivar. Factor (B) was planting methods (direct seeding and transplanting). In direct seeding, seeds were sown in field in mid-October. The seeds were sown in nursery bed in early October and the seedlings transplanted to field at two or three leaf stages. During the experiment characters: height and leaf number, Bolted plants percentage, total and marketable yield, doubling bulb percentage, bulb dry matter percentage, and total soluble solid were evaluated and recorded. The bolted plants and doubling bulb percentage in direct seeding were significantly higher as compared with transplanting method at 1% probability level. The effect of planting methods on total and marketable yield was not significant. Primaver cultivar produced the highest total and marketable yield. However no significant difference was recorded for total yield between Primavera and Ramhormoz landrace. The results of economic analysis indicated that direct seeding was more benefit than transplanting method. The highest cost and gross income were recorded for transplanting and direct seeding methods in Primavera cultivar respectively. The maximum benefit to cost ratio and net present value were found for direct seeding of improved population of Behbahan onion.

To evaluate quantitative and qualitative traits as well as thrips resistance of onion genotypes, an experiment was conducted at Behbahan Agricultural Research Station, Behbahan, Khuzestan, Iran from 2013 to 2015. The experiment was a split plot based on a randomized complete block design with three replications. Pesticide-treated and pesticide-free plots were considered as sub plots and ten onion genotypes (Behbahan, Padook, Ramhormoz, Iranshahr, Borazjan, Dorcheh Esfahan, and Kamerei Khomain landraces, Primavera and Texas early grano cultivars and improved population of Behbahan onion) were considered as main plots. The seeds were sown in nursery bed in early October and the seedlings were transplanted into the field at 2-3 leaf stage in mid-November. The bulbs were harvested when 50-80% of foliage top had fallen and collapsed. Among different thrips species the Thrips tabaci Lindeman was the predominant in the experimental field. To control the thrips, the pesticide was applied 4 and 3 times in the first and second years of experiment, respectively. Leaf length, total and marketable yield, mean bulb weight and bulb dry matter percentage were significantly higher in the pesticide-treated plots than in the pesticide-free plots. However, thrips population was significantly lower   in the pesticide-treated plots than the pesticide-free ones. Also, the spraying had not significant effect on the number of leaves. Due to the lack of significant differences between total and marketable yield of Ramhormoz genotype in the pesticide-treated plots and pesticide-free plots, it can be concluded that this genotype is capable of resisting thrips, at least in part, compared to the other genotypes. While Texas early grano cultivar produced the highest yield in the pesticide-treated plots, in the pesticide-free plots the highest yield belonged to Primavera cultivar. According to the results obtained, it can be concluded that the Texas early grano and Primavera cultivars are suitable for cultivation in the presence and absence of anti-thrips pesticides, respectively.

The potatoes produced in temperate regions of Iran are consumed in autumn and early winter, and after that there is a shortage of potatoes in the market. This shortage can be eliminated by potato cultivation in autumn and winter seasons in the southern regions of Iran and supplying products in late winter and spring. Short dormant period, rapid sprouting, early maturity, tolerance to temperature stress and high yielding are characters of cultivars, such  as ‘Savalan’, ‘Javid’, ‘Khaveran’, ‘Banba’ and ‘Jelly’, that  are recommended for   production in southern regions of Iran. The total and marketable yield and qualitative characteristics of potato as well as farmers’ income can increase by application of 25% of required nitrogen fertilizers as vermicompost and use of plant growth biostimulants. Supplying of 80% full irrigation in drip irrigation system from plant emergence to harvesting was recommended to produce maximum marketable yield and the highest water use efficiency. Comparison of the yield of autumn and winter cultivation showed that if frost did not occur, the total and marketable yield of autumn cultivation was significantly higher (3.43 and 4.05 t ha-1, respectively) than winter cultivation. However, due to the probability of frost advents in autumn cultivation, the winter cultivation is preferred.

This experiment was conducted to investigate the influence of integrated management of nitrogen fertilizers on growth, yield and quality characteristics of potato (Solanum tubersom cv Savalan) in Behbahan Agriculture Research Stations from 2014 to 2016. This research was carried out in randomized complete block design including four treatments: lack of nitrogen fertilizer (control), plots that received 50% nitrogen from chemical fertilizer (as urea) plus 50% nitrogen from vermicompost (50%U+50%V), plots that received 75% nitrogen from chemical fertilizer plus 25% nitrogen from vermicompost (75% U+25%V), and plots that obtained 100% nitrogen from chemical fertilizer (100% urea) and three replications. The Results of growth analysis showed that the haulm and tuber growth rate increased during the early stages, while reached a maximum value, following decline in the late season. In the most sampling periods, the highest tuber and crop growth rate were recorded in 75% urea +25% vermicompost. Therefore the highest yield was observed in this treatment. Application of vermicompost significantly increased tuber number, total and marketable yield, nitrogen use efficiency and agronomic nitrogen use efficiency in 75% urea +25% vermicompost and 50% urea +50% vermicompost as compared with 100% urea. The tuber nitrate content in   75% urea +25% vermicompost and 50% urea +50% vermicompost was significantly lower than 100% urea. According to results, the yield and qualitative characteristics of potato (Savalan cultivar) and farmers’ incomes can increase in Khuzestan province by supply of 75% required nitrogen fertilizer through urea and 25% nitrogen from vermicompost.

Using plant resistance inducers leads to the reduction of disease incidence and severity. The effect of several resistance inducer compounds on onion downy mildew disease was tested in a factorial experiment with a randomized complete block design comprising of 10 treatments in 3 replications at Behbahan Agricultural Research Station. Treatments consisted of chemical indicers in five levels of 50mμ dipotassium phosphate, 80mμ nicotinic acid and 3mμ salicylic acid, and ridomil mancozeb fungicide (3g/L) and control that treated with water. Treatments were applied 5 times from mid-February when the plants were in 3 to 4 leaf stage until late April every two weeks. Genotypes were in two levels including modified onion of Behbahan and Early White Texas. Disease severity was calculated by evaluating 40 plants in each treatment when the disease index in the control treatment was more than 75% in two middle rows of each plot in each treatment. The highest percentage of disease severity (75.50%) was observed in the control treatment with no spraying and the lowest rate of disease severity was observed in the application of Ridomil with 14.17%. The severity of the disease was 28.33%, 33.33% and 23.33% in dipotassium phosphate, salicylic acid and nicotinic acid treatments, respectively. Therefore, the use of resistance inducers can be a substitute of fungicides.

Khuzestan province is one of the suitable region for off-seasion production. In this region potato was planted crop from mid November to mid January. Analyses of meteorological data showed that the probability of a frost occurrence is 50% from late December to late February. Therefore potato plants of different planting dates are often subjected to frost in various phonological stages, so that, yield loss will vary depending on the planting date. In fact, this experiment was conducted to evaluate the effects of planting date on yield and agronomic characteristics of potato cultivars, but frost occurrence in mid January created exceptions and special opportunity for us to study the influence of frost occurrence in different phonological stages on recovery rates and some growth indices of potato cultivars.

This study was conducted on the research farm of Behbahan Agriculture Research Station from 2015 to 2016. This research was done in a split plot experiment arranged in a randomized complete block design with three replications. Planting date considered as the main plot, from 1 to to 21 December with 10 day intervals and four cultivars as sub plot (Sante, Savalan, Santana and Almera). five plants were sampled from each sub-plot from 15 days after plants emergence to harvest with 15 days interval and separated into haulms and tubers. Plant tissue was oven dried at 75ºC for 72 hours. The growth indices including haulm growth rate, tuber growth rate, crop growth rare and relative growth rate growth calculated. When the diameter of the swollen tip of stolon was twice as long as stolon diameter, considered as tuber initiation . Tubers were harvested in mid May. After harvest analysis of variance were done by MATAT-C statistical software and means were compared using Duncan’s multiple test range.

When frost occurred, the phonological stages of plants in planting dates of 1 and 11 Dec. were vegetative growth and tuberization stages respectively, so that all haulms were killed, while plants in planting date of 21 Dec. didn’t emergence from soil. The yield of 11 Dec. planting date was significantly higher than 1 Dec at 5% probability level. Haulm growth, crop growth rate and relative growth rate of all cultivars were negative during the first sampling period after frost occurrence. The recovery rate of Savalan cultivar was higher as compared with other cultivars. Due to higher tuber and crop growth rate, Savalan cultivar produced the highest yield in 1 and 11 Dec. The maximum relative growth rate in planting dates of 1 and 11 Dec. were recorded for Sante and Savalan cultivars respectively. The yield of 21 Dec. planting date was significantly higher than1 and 11 Dec at 1% probability level.

The findings of this study suggest that to minimize the risk of yield loss by frost, planting of potato should be avoided before late January in Khuzestan province and Savalan cultivar is recommended for this area.

This research was conducted at the Behbahan Agriculture Research Station, Behbahan, south-west of Iran, for two years from 2016 to 2018 to study the postharvest losses of short-day onion cultivars in uncontrolled storage conditions (no heating, cooling and ventilation systems). Seeds were sown in nursery in early October and seedling transplanted at 2-3 leaf stage. Bulbs were harvested when 50-80% of foliage had dried and fallen and prepared for the experiment in both years. In the 1st year of experiment, the average of daily storage temperature and relative humidity ranged from 14.5 to 40.5°C and 27 to 60%, respectively. The average of daily storage temperature and relative humidity varied from 15 to 38 °C and 30 to 71%, respectively, in the 2nd year of experiment. This research was performed using a split plot experiment based on a randomized complete block design encompassing 80 treatments with 4 replications. Main plot consisted of 10 cultivars (‘Seba’, ‘Texas Early White’, ‘Imperateriz’, ‘Siroos’, ‘7030’, ‘X P red’, ‘Sapidan’, ‘Golden I’, ‘Texas Early Grano’ and ‘Primavera’) and bulbs evaluation in storage  at eight times  (one months after  start of storage with one month interval) was considered as sub plot. The monthly bulb weight losses percentage decreased with time. The minimum weight loss (9.56%) was recorded in ‘Seba vultivar. The damage of black mold increased until the fourth month of storage and then decreased. ‘Sapidan’ was the most sensitive cultivar to damage of black mold (23.23%). The highest percentage of bulb rotting (29.65%) was observed in ‘Texas Early White’ cultivar. Bulb sprouting was observed from the fifth month of storage and the highest bulb sprouting (19.88%) belonged to ‘Siroos’ cultivar. Results were suggestive of difference in storability among cultivars, the maximum and minimum storability being recorded in ‘Seba’ and ‘Sapidan’, cultivars, respectively.

Temperature based agro-meteorological indices such as growing degree days and helio thermal unit have been reported quite useful to predict the growth and yield of crops. The efficiency of converting heat and radiation energy to dry matter depends on the genetic factors, sowing date and crop type. Hence, the knowledge of calculation heat thermal summation unit, mostly called the growing degree days and its further mathematical derivations like helio thermal unit and heat and radiation use efficiency will be the basic prerequisite of phenology periods and optimum planting date for different crop varieties. In spite of much researches have been done about onion in country, no paper have already published related to study the agro-meteorological indices at phonological stages of this crop. This experiment was conducted to study the effect of planting date on agro-meteorological indices at phenological stages and yield of Behbahan bred onion.

This research was conducted in randomized complete block deign including four planting dates from 6 September to 21 Octobers with 15 days interval contain four replications at Behbahan Agriculture Research Station for two years (2014-16). In this experiment studied genotype was Behbahan bred onion. Seedlings were transplanted (at two or three leaf stage). Fertilizers were applied based on soil analysis results according the recommendation of Soil and Water Research Institute.Time of bulbing was estimated based on bulbing ratio and cumulative sums. Agro-meteorological indices including growth degree days, helio thermal unit and photo thermal index were calculated at seed germinations, vegetative growth and bulbing and bulb development stages. Bulbs were harvested when 50-80% of foliage top had fallen and collapse. Statistical analysis was performed using MSTATC software and mean comparisons were also performed using Duncan’s multiple range test at P≤0.05.

The lowest duration between plant to seedling emergence and minimum growth degree days at seed germination stage were appointed to planting date at 6th September. The maximum photo thermal index during seed germination stage belonged to 21st September and 6th Octeber planting dates in the first and second year of experiment, respectively. The maximum growth degree days and helio thermal unit during transplant production belonged to 21st September planting date as well as with delaying planting date these indices decreased. The differences of obtained growth degree day in all studied planting dates were not considerable in plant growth period (Except of sowing date at 6th October in the first year) during two years. The highest yield, thermal use efficiency and helio thermal ones were recorded for 6th and 21st September planting dates in the first and second year, respectively. Reduction of growth and development of bulb in sowing date at 21st October and being exposed to high temperature at the late of this stage led to produce the lowest yield at this planting date.

According to the results, the best planting date is 21st September for Behbahan bred onion and delaying sowing date caused in yield reduction.

Growing degree days (GDD) and helio thermal units (HTU) are the temperature based agro-meteorological indices that play important role in predicting crop growth and yield. Growing degree days is based on the concept that the actual time to achieve a phenological stage is linearly related to base temperature (Tb) and optimum temperature. The efficiency of conversion of heat and radiation energy to dry matter depends on genetics factors and planting date. Heat summation units (HSU), that mainly called growing degree days, and its derivations such as helio thermal units are the most necessary to determine phenological stages and the suitable planting dates for cultivars of different crop. Growth of potato can be divided into five stages: sprout development, vegetative growth, tuber initiation, tuber bulking and maturation. There is little information concerning of growing degree days and helio thermal units for potato in the sub-tropics. This experiment was undertaken to define growing degree days and helio thermal units at phenological stages and effect on yield for potato cultivars established at different planting dates.

The research was conducted in the research farm of Behbahan Agriculture Research Station for two years (2015-2017). The experiment was arranged as a split-plot in a randomized complete block design with three replicates. Planting dates from 21 December to 20 January at a 10-day interval were the main plot and the Cozima, Savalan, and Elmera cultivars were considered as sub-plot. When the diameter of the swollen tip of stolon was twice as long as stolon diameter, considered as tuber initiation. Tubers were harvested in mid May. Growing degree days and helio thermal untis were calculated at all phenological stages and after harvest thermal use efficiency and helio thermal unit use efficiency. Results from experiments of 2 years were combined for analysis. Data were statistically analyzed by MSTAT-C. Significant differences among treatments means were determined at p ≤ 0.05 by Duncan’s multiple test range.

The longest of the sprout development stage was recorded for 21 Dec. planting date. With the postponement of planting date, due to increase temperature, duration of sprout development significantly shortened, and growing degree days and helio thermal unit decreased. The duration of vegetative stage was 15 days. Early exposure of plants to favorable climatic conditions for tuber initiation, short day and cool night temperature, caused the duration of vegetative growth, growing degree days and helio thermal unit were low. Tuber initiation is thought complete within 2-6 weeks of that event, but since the majority of the tubers are formed over a period of 15 days, duration of this stage is usually considered about 15 days. Although the duration of tuber initiation was equal in all planting dates, however there was significant difference between the amount of growing degree days and helio thermal unit in some treatment dates due to unsimultaneous timing of tuber initiation. The duration of tuber bulking, depend on planting date and cultivar, ranged from 38 to 44 percent days. Growing degree days and helio thermal units at tuber bulking stage were higher than previous stages, such as depend on planting date 61.52 to 66.27 percent of total growing degree days belong to tuber bulking stage. Maturation stage was not observed. There were no significant differences for yield and helio thermal unit use efficiency among all planting dates, however the highest thermal use efficiency was recorded in 20 Jan. planting date. The highest yield, thermal use efficiency and helio thermal units use efficiency belong to Savalan cultivar. Climatic conditions at sprout development, vegetative growth and tuber initiation stages were relatively more favorable for Savalan cultivar in 20 Jan. than other planting dates. Moreover, plants of Savalan cultivar in 20 Jan. planting date, during incidence of late blight in effect of less age were more tolerant as compares with other planting dates. Therefore, the yield of Savalan cultivar in 20 Jan. was significantly higher than other planting dates.

The duration of sprout development and vegetative stages are long and short respectively. In this experiment low temperature during sprout development and high temperature from mid tuber bulking stages caused the less tuber yield than temperate regions of the country. According to results, planting of Savalan cultivar in mid January is recommended for winter potato production in Khuzestan province. Planting from mid December to mid January is recommended for Cozima and Elmera cultivars.

This research was conducted to compare the qualitative and quantitative characteristics of open-pollinated and hybrid short day onion cultivars in Khuzestan climatic conditions. The experiment was done in randomized complete block deign including 15 cultivars (10 hybrid and 5 open-pollinated) with four replications at Behbahan Agriculture Research Station for two years (2016-18). Seeds were sown in nursery in early October and seedling transplanted in early November. Bulbs were harvested when 50-80% of foliage top had fallen and collapse. Siroos cultivar (hybrid) produced the highest yield. The decrease yield of Seba and SV 4043 (hybrid cultivars) as well as Texas Early White, Texas Early Grano, and Sapidan (open-pollinated cultivars) were not significant as compared with Siroos. Group comparison of the qualitative and quantitative characteristics in open-pollinated and hybrid cultivars was performed using partitioning of treatment effects. The bolted plants were significantly higher in open –pollinated than hybrid cultivars. But the differences of the other characteristic were not significant in open –pollinated and hybrid cultivars. The price of open –pollinated seed, especially due to increase price of foreign exchange in recent years, is much less than hybrid seed. In addition, seed of open pollinated cultivars could be produced by growers. Therefore, planting of open pollinated cultivars namely Texas Early White, Texas Early Grano, and Sapidan are recommended for onion production in Khuzestan province.

Onion is one of the most important vegetable in Iran. Harvested area of onion is 63685 hectars. Significant amount of short day onion seed is imported to Iran that caused genetical deperssion of landraces onion. However, high diversity have been reported in Iranian landraces onioin. Populations that produced high yield, exhibited long storability and resistant to pests have been observed in landraces onion. Therefore study the qualitative and quantitative characters of landraces onion are very important. This research was conducted to study bulbing date, morphological characters and correlation coefficient among characters in landraces onion of southern Iran and commercial cultivars.

This research was conducted in randomized complete block deign including eight populations (Behbahan, padook, Ramhormoz, Iranshahr and Borazjan landraces, Texas early grano and Primavera cultivars and Behbahan bred onion) with four replications at Behbahan Agriculture Research Station for two years (2012-14). Seeds were sown in nursery in early October and seedling transplanted (at two or three leaf stage) in mid Novenmber. Earliest time of bulbing was estimated using bulbing ratio and cumulative sums. Bulbs were harvested when 50-80% of foliage top had fallen and collapse. Results were analyzed by MSTATC statistical software and comparison of meanes were done using Duncan,s Multiple Range Test.

In the first year of experiment bulbing occurred from photoperiod of 11 h and 56 min (19 March) to 12 h and 5 min (22 March). Bulbing dates were from photoperiod of 12 h and 32 min (31 March) to 13 h and 5 min (18 April) in the second year. The highest total yield were produced by Padook landrace and Texas early grano cultivar in the first and second year respectively. Parimavera cultivar produced the highest marketable yield. Bolting was not observed in Perimavera and Texas early grano cultivars. Primavera cultivar and Borazjan landrace showed the highest and lowest doubling bulb respectively. The highest bulb dry matter percentage belong to Behbahan bred onion. Results of correlation coefficient indicated total and marketable yield exhibited significant negative correlation with bolted plants and doubling bulb. Bulb dry matter percentage had positive and significant correlation with total soluble solid percentage.

Bulbing occurred on short day in all studied populations. According to results Texas early grano is The best cultivar for onion production in Khuzestan province. Among landrace populations, Behbahan bred onion in regard to low sensitivity to doubling bulb and high bulb dry matter percentage is superior population.

The aim of this study was to investigate the influence of different nitrogen sources on qualitative and quantitative characters and economic benefit of potato (Sante cultvar). This experiment was conducted in a randomized complete block design with four treatments and three replicates at Behbahan Agriculture Research Station, Behbahan, south-east Iran, in two years (2014 and 2016). Treatments were: 0 nitrogen fertilizer, 50% nitrogen from chemical fertilizer (as urea) + 50% nitrogen from vermicompost (50% M+50%V), 75% nitrogen from chemical fertilizer + 25% nitrogen from vermicompost (75% M+25%V) and 100% nitrogen from chemical fertilizer (100% M). The total and marketable tuber yield, nitrogen use efficiency and agronomic nitrogen use efficiency in 75% M+25%V were significantly higher than the other treatments.  Application of vermicompost in both treatments significantly increased stem and tuber number and decreased tuber nitrate content as compared with 100% M. The effect of vermicompost on tuber dry matter percentage was not significant.  Economic evaluation indicated the highest benefit may be achieved from 75% M+25%V. Supply of 75% required nitrogen fertilizer through vermicompost and 25% nitrogen from mineral fertilizer (as urea) can increase yield and qualitative characters of potato and farmers’ incomes in Behbahan.

In order to study agro-meteorological indices at different phenological stages and yield of new potato cultivars in winter planting in Behbahan Agriculture Research Station an experiment was conducted in randomized complete block design including 11 cultivars in three replications. The results showed that at tuber bulking stage the highest growth degree day and helio thermal unit (respectively 1003.97 °C day and 7301.90°C day hr-1) belonged to Sante cultivar. The maximum photo thermal index in all studied cultivars belonged to tuber bulking stage. Evaluation the correlation coefficient between characters showed that, yield exhibited significant positive correlation with growth degree day (r=0.387) at tuber bulking stage. The highest plant height (67.90 cm) and minimum days to canopy closure (71.33 days) belonged to Savalan cultivar. The highest yield (34.28 t ha-1), heat use efficiency (18.95 kg ha-1°C day-1) and helio thermal use efficiency (2.06 kg ha-1°C day hr-1) were found in Savalan cultivar. According to result Savalan, Ottawa, Jelly, Georgina and Bunba cultivars are recommended for winter potato planting in Behbahan.

In order to evaluate the effect of autumn and winter planting on yield and phenology of potato cultivars using thermal indices an experiment was coducted in split plot in time based on a radomized compelet block design with three replications at Behbahan Agriculture Research Station in Khuzestan province, south of Iran in 2014 and 2015. Cultivar (Sante, Savalan and Javid) was considered as main plot and planting season (autumn and winter planting) as sub plot. In Autumn and winter planting seasons tubers were planted in early October and early December, respectively. Tubers were harvested in early March and mid May in autumn and winter planting seasons, respectively. The duration of sprout dvelopement in the autumn planting season was 14 days shorter than winter planting season, but tuber bulking duration was 25 days longer in the latter planting season. Futhermore, growing degree days, helio thermal unit and photo thermal index of sprout development stage in autumn planting season (117.41°C day, 1967°C day hour and 9.29°C day day-1, respectively) were greater than winter planting. However these agro-meteorologial indices at tuber bulking stage (537.58°C day, 4168.79°C day hour and 10.42°C day day-1, respectively) were smaller in winter planting. Yield, thermal use efficiency and helio thermal use efficiency were reduced (18.36, 34.95 and 31.58%, respectively) due to high temperatures encountered during tuber bulking stage in winter planting as compared with the autumn planting season. The highst yeild, thermal use efficiency and helio thermal use efficiency in both of planting seasons belonged to Javid cultivar.

Stability of yield and other important characters of eight short day onion genotypes (Behbahan, Padook, Ramhormoz, Iranshahr and Brazjan landraces, Primavera and Texas Early Grano cultivars and  Behbahan bred onion) were studied using a randomized complete block design with four replications at Behbahan, Minab and Iranshahr Agriculture Research Stations for two years (2012-14). Genotype × environment interaction (GEI) was evaluated through GGE biplot. Using polygones for grouping of environments based on total yield showed that each location was considered as a mega environment. In Behbahan, Minab and Iranshahr locations, Texas Early Grano, Brazjan landrace and Primavera cultivar produced the highest total yield respectively. In regard to marketable yield two mega environments were identified. The first mega environment contains Minab and Iranshahr, the second mega-environment only contained Behbahan. According to the GGE biplot analysis of the ideal environment, it was concluded that Iranshahr and Minab were closest to the ideal environment for bolting and bulb doubling, respectively. For total and marketable yield Behbahan was closest to the ideal environment. Iranshahr and Behbahan was nearest to ideal environment for bulb dry matter percentage. Evaluation of genotypes through average environment coordinate indicated that Texas Early Grano was the best genotype in term of total yield and performance stability. Based on marketable yield, bulb doubling and bolting and performance stability, Primavera was the best genotype.

Water limitation is one of the most important inhibitors of crop production, so choosing an optimal and superior strategy for using water in conditions of water shortage is essential. Khuzestan province has been ranked third with 13.8 percent of the total date production of the country. Therefore, using pressurized irrigation methods with the goal of optimal utilization of water resources is inevitable. This research was carried out with the aim of investigating the possibility of utilizing subsurface drip irrigation systems in date orchard and determining the most suitable irrigation treatments in terms of yield and water use efficiency in Zahedi cultivar. The treatments consisted of the amount of water consumed by subsurface drip irrigation in three levels based on 75, 100 and 125% water requirement and in surface drip irrigation based on 100% water requirement. Data analysis was performed using a randomized complete block design with three replications. This research was carried out on Zahedi date palm cultivar at Behbahan Agricultural Research Station during three years (2013-2015). In the number of fruits in the cluster, treatments of 75, 100 and 125% of crop water requirement and surface drip irrigation, respectively, with 1438.1, 1336.8, 1492.8 and 1449.8 of fruits in the common cluster were in same place. The surface treatment and 75% of water requirement respectively had the highest yield of 8569.6 and 7802.2 kg / ha, but the difference between mean treatments was not significant. The water use efficiency under 75% of the water requirement treatment was highest with the production of 7444 kg of dates per cubic meter of water. The 75% water requirement treatment had the lowest moisture content and the final rating was 8.7%. The 75% water requirement treatment with 13.7 N / m2 had the highest rigidity and loneliness was in the first place. In the index of total soluble solids, 75, 100 and 125% treatments of subsurface drip irrigation and surface drip treatments were respectively 60.2, 59.5, 59.9 and 60.2 at the same place. Optimizing water use and reducing it to 6116.53 cubic meters per hectare in 75% water treatment will save water consumption. As this treatment decreased 20.4, 19.7 and 39.4% was use, respectively, compared to the surface drip and 100 and 125% water treatments.
This undesirable amount of water consumption has not been significantly attributed to the quantitative traits and some qualitative traits such as pH, soluble solids and sugar content in sub-surface drip treatments. Regarding the insignificant impact of irrigation levels in subsurface drip treatments, it is possible to use other irrigation treatments such as 50 and 60% water requirement in future studies of subsurface drip irrigation.

In order to compare the storability of short day onion populations and cultivarsin non-controlled storage, this research was conducted at Behbahan Agriculture Research Station from 2013 to 2014 for two years. Seeds were sown in nursery in late September. Seedlings were transplanted at 2-3 leaf stages. Evaluation of bulb storability was performed by using split plot experiment based on RCBD with four replications. Main plot consisted of eight populations and cultivars (Behbahan, Padook, Ramhormoz, Iranshahr and Brazjan landraces, Primavera and Texas Early Grano cultivars and improved population of Behbahan onion) and six storage times (1, 2, 3, 4, 5 and 6 months) considered as sub plots. The monthly bulb loss weight percentage decreased with passing time. Improved population of Behbahan onion had the most sever weigh losses (20.26%). Damage of black mold increased until the third month of storage and then decreased. Ramhormoz landrace was the most sensitive genotype damaging from black mold (39.47%). The highest percentage of bulb rotting (29.65%) was recorded for Primavera cultivar and storability of this cultivar was significantly lower than other genotypes. Bulb sprouting was observed from the third month of storage. Iranshahr landrace had the highest bulb sprouting (31.57%). Results showed that according to storability, improved population of Behbahan onion and Texas Early Grano were better than other genotypes.