مجله تولید گیاهان زراعی
سال ششم شماره 4 (زمستان 1392)

In arid and semi arid، seedling emergence and establishment are key stages for final plant density in chickpea production. Drought stress، especially at the end of the growing season، is one of the factors which decrease a main part of chickpea grain yield in these areas. Therefore the aims of this study were assess to the effects of hydro priming and hormonal priming by gibberellin and abscisic acid on some growth indicators and yield of chickpea under rain-fed and irrigated conditions. Seeds primed with 0 (hydro priming)، 50، 100 and 150 ppm of each phytohormones. Non-primed seeds also were sowed. Examined chickpea cultivar was Flip 93-93 (Known as Azad cultivar). Rain-fed conditions shortened the plant life cycle and decreased time to flowering and podding. Quantity of yield and yield components were less in the rain-fed conditions than irrigated conditions. Irrigation increased grain and biologic yields so grain yield was 439. 88 and 689. 48 kg/ha for rain-fed and irrigated conditions respectively. Hydro-priming could increased the number of secondary lateral branches، LAI، grain yield، and harvest index in comparison to the other priming treatments and control (non-primed). Gibberellin priming delayed days to flowering and podding about eight days. The highest correlation of grain yield obtained with biological yield (r=0. 92)، HI (r=0. 84)، 100-seed weight (r=0. 39) and number of pods per plant (r=0. 36).

Precise application of the N fertilizer rate is critical to achieve maximum yield. In major regions، empirical methods were used for determining N fertilizer requirement. These methods cannot take into account variation in management and environmental conditions on determining fertilizer requirement. Crop simulation models can provide an alternative means of determining the optimum crop N requirement under varied management and climatic conditions. In the present study for assessment of N fertilizing of wheat farms in Gorgan region، we conducted a survey on 95 wheat farms integrated with simulation experiment using CropSyst model. On-farm assessment showed that the amount of applied and recommended N fertilizer application varied between 45-175. 5 and 67. 5-146. 3 kg ha-1، respectively. In addition، the amount of applied N fertilizer on 72 farms was more than recommended N values. Comparison of applied and recommended N fertilizer to optimum N fertilizer estimated by simulation model (171 kg ha-1) showed that the amount of applied N fertilizer on 93 farms and the amount of recommended N fertilizer on all farms were lower than optimum N fertilizer. This indicated that there was a gap between both applied and recommended fertilizer with optimum N fertilizer and this gap was more between recommended and optimum value. Therefore، it was concluded that the method of fertilizer recommendation on farms has not been effective and the current method of fertilizer recommendation should be revised for achieving the higher yield on farms.

Heat stress is one of the main obstacles for crop production in many areas of the world including southwest of Iran. In order to evaluation the effect of heat stress on yield، yield component، and mopho-phenological traits of wheat، an experiment was conducted during 2010-2011 under normal (optimum sowing date) and heat stress (late sowing date) conditions on 11 wheat genotypes including Yavaroos، Zagros، Chamran، Niknejad، Koohdasht، Alvand، Montana، M6، Kauz، Gohar and Durum-ch-89 in experimental field of Shahid Chamran University of Ahwaz. The experiment in each condition was arranged in a randomized complete block design. Terminal heat stress caused to significant reduction in days from sowing to heading (29%)، days from sowing to maturity (35%)، plant height (31%)، peduncle length (27%)، head length with awn (12%)، head length without awn (15%)، number of spikelet per spike (15%)، number of kernels per spike (19%)، 1000 kernel weight (14%)، biological yield (37%) and harvest index (5%)، and spike/m2 so that these effects resulted in a significant reduction in grain yield (41%). Based on the results morpho-phenological traits were detected as important traits in heat stress studies but number of kernels per spike and harvest index were recommended as convenient traits for screening the heat tolerant lines. Kauz، Chamran and Alvand cultivars were able to maintain the grain yield under heat stress condition and suggested as tolerant cultivars. These cultivars have potectial for direct planting in warm areas or using in breeding programs.

drought stress has been well documented as an effective parameter in decreasing crop production، developing and releasing new varieties which are adaptable to water deficit conditions can be a constructive program to overcome unsuitable environmental conditions. In order to evaluate the adaptation of rice genotypes to drought stress and to identify the tolerant and sensitive genotypes، 15 genotypes were studied in two environments (stressed and non –stressed conditions) using randomized complete block design with three replications in the Research farm of Gonbad Kavos University in 2008 growing season. Analysis of variance showed that there was highly significant effect (p> 0. 01) between genotypes in all traits and in both Environments. Mean comparison showed that the highest yield belonged to Dom siah، Sarkho and Sangjo in nonstressed and stressed respectively. Mean productivity (MP)، geometric mean productivity (GMP) and stress tolerance index (STI) were the most suitable indices showing the highest correlation with yield. Based on MP، GMP and STI and also biplot technique، Garde، Sarkho، Sangjo، IR83752-B-B123، Tarom mahali and Tarom Amiri) were determined as the most tolerant cultivars while BRSBONANC GRALDO being the most sensitive.

In order to study of drought stress on physiological and agronomical characteristics of rapeseed varieties، an experiment was carried out as split plot based on randomized complete block design with three replications at Yazd region during of 2011-2012. Irrigation treatments was designed in two levels as main plot including irrigation after 80 mm evaporation from evaporation pan، class A (control treatment) and drought stress as withholding irrigation from flowering stage، and varieties lilian، Cooper and Savannah as sub plots. Sampling stages was done 7، 12 and 26 days after treatment. The results indicated that drought stress significantly decreased the stomatal conductivity، relative water content (RWC)، plant height، silique per plant، 1000 grain weight and grain yield، whereas، in comparison with control SPAD value was higher. Lilian indicated the higher stomatal conductivity (196 mmol m-2 s-1) and RWC، silique per plant (300 silique)، 1000 grain weight (4. 06 g) and grain yield (1411 kg. ha-1). In this study، Geometric mean productivity (GMP) and Stress tolerance index (STI) had the high correlation with grain yield in normal and drought stress conditions. Also، Bi-plot diagram based on two principal components indicated that Lilian variety with higher GMP and STI indices in addition with higher GMP and STI both in stress and non stress environment had the highest grain yield.

In order to study of relationship between timing and duration of phenological events and grain yield of wheat plants، an experiment was performed at Moghan College of Agriculture and Natural Resources-University of Mohaghegh Ardabili research farm during 2010-2011. The plant materials (81 wheat cultivars) were evaluated using a simple lattice design with two replications under irrigated condition. Dates of various phenological events were recorded based on growing degree day (GDD). The results showed that modern wheat cultivars generally produced more grain yield and harvest index than old cultivars. More grain yield in modern cultivars associated with more grain number per unit area. No significant differences were observed between modern and old cultivars with respect to biological yield and 1000-grain weight. The cultivars analyzed exhibited a large degree of variations in the dates of stem elongation، booting، heading، anthesis and physiological maturity. In the present study، no apparent relationships were found among grain yield and that of the time to stem elongation، anthesis and stem elongation-anthesis phase. Grain yield was significantly correlated with grain filling period (anthesis-physiological maturity phase)، showing that a longer duration of this phase could increase grain yield in the region

It is very important to find the best model to quantify seed germination rate on the response of temperature which it can be used in determination of cardinal temperatures. This study was conducted to evaluation nonlinear regressions models for description wheat (cv. Morvarid) germination rate response to temperatures and water potentials. Therefore، seeds germination rate were evaluated in temperatures of 5، 10، 15، 20، 25، 30 and 37 oC and water potentials of 0، -0. 2، -0. 4، -0. 6 and -0. 8 MPa. Four functions (Dent-like، Segmented، Beta (original) and Beta (Modified)) were evaluated to describe germination rate on the response to temperature and water potentials. The results indicated that the best model was Dent-like. The base، the lower and the upper and the ceiling temperatures were 1. 5، 23. 8، 33. 0 and 41. 0 oC in the optimum conditions of water potential. Cardinal temperatures had no significantly change under different water potentials، except for base temperature. Biological time for germination ranged from 34 to 51 h in different water potentials. Biological time increased about 20 h by decreasing 1 MPa. Estimated parameters and the relations can be used to prediction time to germination or emergence in wheat under wide environmental conditions from normal to drought stress.

A split plot experiment based on complete block design with three replications was carried out to evaluate the effect of irrigation and potassium fertilizer on yield and yield components of green beans, in 2011 at Ahvaz. Two levels of irrigation (normal irrigation and drought) and four levels of potassium sulfate fertilizer (0, 25, 50 and 100 kg ha-1) were evaluated in this study. The results of analysis of variance indicated that there were significant effects of irrigation, potassium sulfate fertilizer and irrigation × potassium sulfate fertilizer interactions on all of the studied traits. The results of mean comparisons indicated in both conditions of irrigation, the high value of yield and yield components were obtained by use of 50 kg ha-1 potassium sulfate fertilizer. The results of trend analysis revealed that effect of potassium Sulfate fertilizer on dry grain yield and yield of green pods can be explained by the quadratic equation. The results of the correlation analysis indicated that there were positive and significant correlation between dry grain yield and plant height, number of grains per pod and number of pods per plant. In conclusion, the results indicated increasing that potassium sulfate fertilizer was partly prevented high reduction of grain yield in drought condition.

This research was conducted to zoning of Gorgan agricultural lands for hulless barley cropping using evaluation of some environmental factors base on Boolean logic and by geographic information system. For this purpose، agro-ecological requirements of hulless barley firstly، identified according to scientific resources. Rating and thematic requirement maps were then provided. Studied environmental-components were: average، minimum and maximum temperatures، precipitation، slope percent، elevation، and soil characteristics (OM، pH، EC and texture). Then، each layer is classified into suitable (1value) and non- suitable (0 value) classes base on Boolean logic. The digital environmental layers overlaid in ArcGIS media. The results showed that most areas of Gorgan agricultural lands were suitable for hulless barley، so that about 46396. 93 hectares of northern and middle parts of Gorgan are the suitable zone. It was found that OM and EC factors were suitable for hulless barley in total studied area. Also، about 16654. 64 hectares of present agricultural lands of Gorgan were not suitable for this crop and these areas had at least one limitation in ecological resources. The non-suitable regions were located in the central and south of Gorgan township. Moreover، results showed that the limitation factors were including: non-suitable texture classes، high slope percent، elevation and EC. In this study، it was found that climate parameters of average، minimum and maximum temperatures had not limitation for hulless barley growing in agricultural lands of Gragan.

Water shortage and its consumption resulted in development of a suitable rice cultivation system which use less water. Therefore، this preliminary research was carried out to study the possibility of coversion of irrigated system of rice cultivation to aerobic. We tested 61 aerobic rice genotypes، in which were developed at International Rice Research Institute (IRRI)، together with 3 diverse local checks such as Fajr، Neda and Tarom. They were tested in an experimental site in Dash-e-Naaz، Sari، Mazandaran in 2009. Experiment was carried out in an augmented experiment design which check varieties were tested in an RCBD with 5 replicates. We evaluated some important agronomical traits including headings (HDG)، plant height (HT)، number of filled (FG) and non-filled grain (NFG) per panicle، grain length (GL) and width (GW)، 1000-grain weigth (TGW) together with some others which was observationaly scored. Analysis of collected data showed that 5 genotypes showed a better performance than the others in aerobic condition for most of the traits in experimental site. Hence، these selected aerobic rice genotypes along with Neda، the best local check which showed a good performance in aerobic condition، could be suggest to be used for further/details tests to select the best genotypes and develop related agronomic managements and apply in rice breeding programs for drought stress condition.