نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction
The concept of sustainability is mainly used as a measure of the temporal or spatial invariance of specific characteristics. Therefore, sustainability can be expressed as the stability of agricultural outputs, especially yield, over long periods of time or in different spatial environments. The idea of applying sustainability analysis methods to cropping systems is not new, however, it does not seem to have been addressed as it deserves. Yield sustainability analyses have gained more importance in recent years, as the increase in climate variability caused by climate change is also associated with a decrease in crop yield sustainability. For example, among the eight crops studied, beans (Phaseolus vulgaris L.) have shown the greatest sensitivity to temperature increase scenarios caused by climate change. Some studies have shown that yield instability in legumes is 30% higher than in spring and autumn cereals. There are two dominant approaches to the comparative advantage index. The first approach is based on the costs and benefits of products, and the second approach is based on the performance and production of products. The first approach often includes economic and monetary aspects, and the second approach includes technical aspects of production. For example, in a study evaluating crop production, watermelon, cucumber, potato, onion, tomato, and rainfed wheat were found to be efficient in terms of production performance and to have a comparative advantage. In contrast, irrigated wheat, irrigated barley, grain corn, long-grain rice, and short-grain rice did not demonstrate a comparative advantage in production compared with the national level.
Materials and Methods
Official statistics from the Ministry of Agricultural Jihad were used to obtain bean yields from (2010-2011) to (2020-2021) and were the source of information necessary for this research. Yield, relative yield, yield sustainability index, and cumulative comparative advantage were among the items measured in this study. Provincial data were tested using a randomized complete block design with 10 replications (years) and compared means using Duncan's range test. Although changes in genotypes, crop management, economic factors, and weed and pest control vary from year to year, the principle of yield stability calculations does not distort the results, but to reduce these effects, the number of base years was only 10 years. The minimum number of years to measure yield stability indices is 4 years. Usually, there are two opinions on dealing with outliers in yield stability studies: one is that these data should be eliminated, and some believe that these data should be retained because they reflect biotic and abiotic stresses in the studies. In the present study, there were no outliers due to the limited number of years of evaluation, and therefore all data were retained for the provinces.
Results and Discussion
Yield, relative yield, sustainability index, and comparative advantage were the factors evaluated in this study. The yield range of bean seeds fluctuated from 940 kg ha-1 in South Khorasan to 2816 kg.ha-1 in Zanjan. 58 percent of the 31 bean-producing provinces had a yield of less than 2 tons ha-1. In terms of relative bean yield index, the provinces of the country are divided into three groups, with only 48.4 percent of the provinces having a relative yield of more than 100. Provinces such as Fars, Zanjan, Chaharmahal and Bakhtiari, Isfahan, and Markazi had bean yields of more than 2 t.ha-1, and at the same time, the yield sustainability index in them was more than 0.7. In terms of relative advantage in area, only 5 provinces had a comparative advantage, and in these provinces a significant level of cultivation was devoted to bean crops. The relative yield advantage was more than 1 in 9 provinces and more than 2 in 3 provinces. The cumulative comparative advantage of bean cultivation in the country showed that the provinces of East Azerbaijan, Chaharmahal and Bakhtiari, Zanjan, Fars, Kohgiluye and Boyer Ahmad, Lorestan and Markazi have cumulative comparative advantage for bean cultivation. According to the results obtained, it is suggested that policies for bean production in the country be made according to similar indicators of this research.
Conclusions
Ensuring a promising future for crop production depends on an accurate analysis of past production trends. Monitoring yield, relative yield, yield stability, and the comparative advantage of production are among the tools used to analyze the historical performance of crops. Over a decade of bean cultivation in the country, bean seed yield across the 31 bean-producing provinces ranged from 940 kg ha⁻¹ in South Khorasan to 2,816 kg ha⁻¹ in Zanjan. However, 58% of the producing provinces still had yields below 2 t ha⁻¹. The relative yield of beans exceeded 100 in 15 provinces. In terms of yield stability, only 16% of the bean-producing provinces both achieved yields above 2 t ha⁻¹ and maintained these yields over time, indicating substantial yield fluctuations in most producing provinces. In terms of relative advantage, only 5 provinces had a comparative advantage, and in these provinces a significant level of cultivation has been devoted to the bean crop. The relative advantage of yield in 9 provinces was more than 1 and in 3 provinces more than 2. If both the level and yield are the basis of the relative advantage (cumulative relative advantage), the provinces of East Azerbaijan, Chaharmahal and Bakhtiari, Zanjan, Fars, Kohgiluye and Boyer Ahmad, Lorestan and Markazi have such an advantage for bean cultivation. According to the results, the strengths and weaknesses of bean production in each province are specific to that province and can be traced through the indicators presented in this article.
کلیدواژهها English
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