Bita Mahdavi Amiri; Jafar Kambouzia
Abstract
Introduction: Concerns about the potential effects of climate change on agricultural products have prompted significant research in the past decade. Cereals are the most important food in the world population and among the various cereals, wheat plays the most important role. In our country, wheat is ...
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Introduction: Concerns about the potential effects of climate change on agricultural products have prompted significant research in the past decade. Cereals are the most important food in the world population and among the various cereals, wheat plays the most important role. In our country, wheat is the most important crop in the country and has a significant role in feeding people. Due to the importance of this plant in providing food security, this study was conducted to investigate the increase in the concentration of carbon dioxide on the yield of wheat. For this purpose, meta-analysis method was used to quantitatively compare the effect of CO2 on wheat crop yield. Material and methods: The purpose of meta-analysis is to obtain more information than available information. In order to obtain the necessary data for the present study, the printed sources review method was used. 75 articles were extracted on the effect of increasing carbon dioxide concentration on wheat yield, then duplicate articles and articles that lacked the desired data were removed and among the remaining articles CO2 information, sample size, average and standard deviation was extracted. In the next step, these values were recorded in Excel software and finally, using Stata 16 software, the necessary forest plot and funnel plot were drawn, and to investigate the publication bias among the studies using the trim and fill method and drawing its graphs, this was investigated. Results and discussion: The results of the forest plot showed that after deleting the outlier data, the two groups T2 (15-25) and T3 (35_25) have a greater final size effect (about 1.6), which indicates that with increasing temperature up to Wheat plant yield increased by 35 ° C. Also, group T0, which is not mentioned in the articles of this group, has the lowest size effect (0.38). So, it can be inferred that the yield of wheat plant will increase with increasing temperature between 15 to 35 ° C and with increasing CO2 concentration in this temperature range. Examination of the funnel plot showed that most studies had accumulated at the top of the diagram. These studies have smaller standard error, larger sample size and higher accuracy. Publication bias was also observed in a positive direction. After drawing the funnel plot, the trim and fill method was used to estimate the potential missing studies due to the biased dissemination in the funnel plot and the adjustment of the estimate of their overall effect. After performing the trim and fill method, 6 dots marked in orange are added. These points are missing studies that need to be placed to create symmetry in the graph. This indicates that previous studies have been positive. Conclusion: The results of this study showed that the studies conducted in recent years have more reliable results (due to the larger sample size and greater accuracy in the results of these studies). Also, considering that increasing the concentration of CO2 can also cause an increase in temperature, it is suggested that in future studies, studies that have examined the interaction between increasing the concentration of CO2 and increasing the temperature simultaneously on important crops, using the meta-analysis method should be examined.
Amin Gharanjik; Jafar Kambouzia; Saeed Soufizadeh
Abstract
Introduction: Plants show different morphological and phonological responses to ecological conditions within their tolerable range, which are in fact part of their heredity. These changes have a key role in species survival and ecosystems sustainability. Agricultural ecosystems are very fragile due ...
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Introduction: Plants show different morphological and phonological responses to ecological conditions within their tolerable range, which are in fact part of their heredity. These changes have a key role in species survival and ecosystems sustainability. Agricultural ecosystems are very fragile due to the severe limitations of genetic diversity and biodiversity. In an agro-ecological approach, unlike current agriculture, careful consideration of the livelihood stages and other living organisms in the ecosystem is of interest, and so it is attempted to manage production as well as the optimal use of agricultural inputs. Material and methods: In order to study the phonological changes in four bread wheat genotypes (Gonbad, Karim, Koohdasht, Morvarid), at different levels of urea fertilizer application (0, 66, 200 kg/ha), a factorial experiment was conducted in a randomized complete block design with three replications in two crop years of 2014 and 2015 at Agricultural Research Station of Gonbad-e-kavoos. Results and discussion: The results of this study showed that the length of vegetative and reproductive stages in these two years are different, and the effect of urea content on these stages is not the same in different ecological conditions. Therefore, it was concluded that under different temperature and humidity conditions. it is possible to apply fertilizer management, without having a significant effect on the length of the phonological periods. Observations of this experiment showed that the stalking stage is more stable compared to the previous steps, so that the length of this stage was only 0.63 day in two years, and changes in different levels of fertilizer application did not show any significant difference in two years. It seems that the length of this period is less influenced by environmental factors than the other stages of wheat growth and in other words. it is expected to have a higher inheritance. Changes in the pregnancy stage are also relatively similar to the stalking stage. Even though the consumption of 200 kg/ha urea fertilizer slightly increased the change of the slope, in such a way that 68% slope the increase of the span of the period from the treatment until 66 kg/ha, urea fertilizer is changed into 111.9%, but the amount of this increase is only 0.75 day. It can be concluded that although the length of this stage of plant growth is more affected by environmental factors over the pregnancy stage, in general, the amount of this impact is not high. Observations of this study showed that the studied wheat cultivars (whether they are introduced for dry conditions or supplementary irrigation) during the course of their growth reached the stages of emergence of spike, flowering, and seedling 7.5 to 8.5 days later in the second year (pluvious) than the first year (lower rainfall). So that the difference between these two years for the emergence of the spike on average was 8.33 day, for flowering stage 7.72 day, and for the processing stage 7.56 day. Changes in fertilizer use in these three steps were similar in both years. Conclusion: This study is important in management and controlling the population of non-cultivated plant species, pathogens (fungi and bacteria), insects and other species in the amount and sustainability of crop production.
Saeid Bakhshipour; Jafar Kambouzia; Korous Khoshbakht; Abdol Majid Mahdavi Damghani; Maryam Hosseini Chaleshtori
Volume 15, Issue 2 , July 2017, , Pages 163-180
Abstract
Introduction: One of the main problems in rice cultivation and production is the lack of water resources, especially during periods of low rainfall which affect vegetative growth rate and the level of yield. Drought stress has been well documented as an effective parameter in decreasing crop production, ...
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Introduction: One of the main problems in rice cultivation and production is the lack of water resources, especially during periods of low rainfall which affect vegetative growth rate and the level of yield. Drought stress has been well documented as an effective parameter in decreasing crop production, and developing and releasing new varieties which are adapted to water deficit conditions can be a constructive approach to overcoming unsuitable environmental conditions. Hence, the characterization of genetic diversity and germplasm classification for parental selection in breeding purposes is of great importance.Materials and methods: In order to evaluate the adaptation of rice genotypes to drought stress and to identify tolerant and sensitive genotypes, 20 genotypes were studied using a factorial randomized complete block design with three replications at the Rice Research Institute (Rasht). During growth stages, some traits were recorded such as plant height, total and fertile tiller number, flag leaf area, panicle length, filled and empty grain number, 100-grain weight, number of days to maturity and yield.Results and discussion: Mean comparison showed that the lowest percentage changes in traits among local varieties (Hashemi, Alikazemi and Sangjo) and improved cultivars (Dorfak, Sepidrood and Shiroodi) respectively. Cluster analysis using Ward’s minimum variance and squared Euclidean distance for agronomic traits divided the genotypes into two groups. The separated varieties were grouped in clusters with high quality on the basis of morphological traits and this guides us to select the most different and the best for hybridization programmes, especially to hybridize with local varieties in order to create new varieties resistant to stress. The result of factor analysis based on the principal component showed that factors three and four accounted for 73- 85 of total variance. Conclusion: For the selection of genotypes with high yield and stress tolerance in rice, total and fertile tillers, days to maturity, flag leaf area, panicle length and 100-grain weight could be considered through estimating suitable selection indices for these traits. local and improved cultivars. The study found that the different groups show genetic variation in rice genotypes
Sajjad Rahimi Moghaddam; Jafar Kambouzia; Reza Deihimfard
Volume 14, Issue 3 , October 2016, , Pages 27-40
Abstract
Introduction: Iran is located in an arid and semiarid region that is vulnerable to environmental changes. So, it would appear that the occurrence of climate change in this region would have a significant impact on agricultural production systems (Eyshi Rezaie and Bannayan, 2012). Climate change might ...
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Introduction: Iran is located in an arid and semiarid region that is vulnerable to environmental changes. So, it would appear that the occurrence of climate change in this region would have a significant impact on agricultural production systems (Eyshi Rezaie and Bannayan, 2012). Climate change might affect the water available for agriculture and, consequently, lead to drought occurring in semiarid areas (Koocheki et al., 2006). Evaluating adaptation strategies, such as changing the planting of dates, can help to increase maize water use efficiency under climate change conditions (Ramprasad et al., 2016). One of the cheapest ways to measure the effects of climate change on agricultural production is through a modelling approach and application of simulation models (Manschadi et al., 2010). Materials and methods: This study aims at investigating the sowing date as a strategy for maize adaptation and improving its water use efficiency under climate change conditions in Khuzestan Province. For this purpose, six locations in Khuzestan Province were selected (Ahwaz, Behbahan, Dezful, Izeh, Ramhormoz and Shushtar). Daily long-term climatic data including minimum and maximum temperatures, rainfall and global radiation in a baseline period (1980-2010) were collected for these locations from their meteorological stations. Then, daily long-term climatic data were generated for the future period of 2040-2069 in these locations by using a method proposed by AgMIP under two climate scenarios (RCP4.5 and RCP8.5). In this study, the SC704 cultivar was used. Taking into account three sowing dates (4 February, 19 February [a common sowing date] and 5h March), six locations, and two climate scenarios over 30 years, a total of 1620 simulation experiments were carried out in this study. In order to simulate the growth and yield of maize under different sowing dates, the APSIM model was applied.Results and discussion: Results indicated that early sowing date (4 February) with 10117.1 kg ha-1 had a higher economical grain yield compared to 19 February (10061.3 kg ha-1 ) and 5 March (7194.6 kg ha-1 ). Also, in the future period, the reduction percentage in economical grain yield at the different sowing dates compared to the baseline common planting date (19 February) showed that the early sowing date of 4 February recorded less reduction (-3.3 and -4.5 percent under RCP4.5 and RCP8.5, respectively) than 19 February (-6.5 and -6.7 percent under RCP4.5 and RCP8.5, respectively) and 5st March (-31.1 and -23.2 percent under RCP4.5 and RCP8.5, respectively). On average in Khuzestan Province, an early sowing date indicated higher water use efficiency (WUE) )11.8 kg ha-1 mm-1 ) compared to 19 February (10.7 kg ha-1 mm-1 ) and 5 March (7.6 kg ha-1 mm-1 ) in the baseline period. However, under climate change conditions, reduction of WUE in different planting dates compared to the baseline common sowing date (19 February) revealed that 4 February (2.8 and 3.3 percent under RCP4.5 and RCP8.5, respectively) was superior compared with 19 February (-12 and -11 percent under RCP4.5 and RCP8.5, respectively) and 5 March (- 40.1 and -32.5 percent under RCP4.5 and RCP8.5, respectively) in term of WUE in Khuzestan Province. Conclusion: In general, according to the results found the common sowing date of maize in Khuzestan is not optimal for maize in terms of water use efficiency and economical grain yield. Accordingly, to increase economical grain yield and water use efficiency in both the future and baseline periods at Khuzestan Province, farmers should choose the early sowing date (4 February) compared to the common and late ones.
