Our experimental results demonstrate that Cipro may interfere with the photosynthetic bio-energetic pathway, in addition to causing morphological deformities in higher plants. The range of EC50 values estimated from concentration-response models of the increase in inactive excited PSII Chl units and the decrease in root length are, respectively, 10.3-111.7 and 0.532-0.776 µM, both of which are higher than the respective LOEC values . Although these concentrations are higher than those typically found in surface waters , they are comparable with those found near industrial effluents . Therefore, the observed adverse in vivo response demonstrated here may be relevant to sensitive plants located near high-FQ-containing waters. Finally, the present study not only stresses the need, as pointed out previously , to consider sublethal molecular targets as potential meaningful phytotoxicity end points, but also takes a step toward the evaluation of FQ cumulative effects, a current challenge in the environmental risk assessment of pharmaceuticals , by providing correlations between FQ structures and specific molecular mechanisms of toxic action.Increasing population and consumption have raised concerns about the capability of agriculture in the provision of future food security.Recent estimates suggested that global agricultural production should increase by 70% to meet the food demands of a world populated with ca. 9.1 billion people in 2050. Food security is particularly concerning in developing countries, as production should double to provide sufficient food for their rapidly growing populations. Whether there are enough land and water resources to realize the production growth needed in the future has been the subject of several global-scale assessments. Te increase in crop production can be achieved through extensification and/or intensification. At the global scale, almost 90% of the gain in production is expected to be derived from improvement in the yield, but in developing countries,vertical plant rack land expansion would remain a significant contributor to the production growth.
Land suitability evaluations, yield gap analysis, and dynamic crop models have suggested that the sustainable intensification alone or in conjugation with land expansion could fulfil the society’s growing food needs in the future. Although the world as a whole is posited to produce enough food for the projected future population, this envisioned food security holds little promise for individual countries as there exist immense disparities between regions and countries in the availability of land and water resources, and the socio-economic development. Global Agro-Ecological Zone analysis suggests that there are vast acreages of suitable but unused land in the world that can potentially be exploited for crop production; however, these lands are distributed very unevenly across the globe with some regions, such as the Middle East and North Africa , deemed to have very little or no land for expansion. Likewise, globally available fresh water resources exceed current agricultural needs but due to their patchy distribution, an increasing number of countries, particularly in the MENA region, are experiencing severe water scarcity. Owing to these regional differences, location-specific analyses are necessary to examine if the available land and water resources in each country will surface the future food requirements of its nation, particularly if the country is still experiencing significant population growth.As a preeminent agricultural country in the MENA region, Iran has long been pursuing an ambitious plan to achieve food self- sufficiency. Iran’s self- sufficiency program for wheat started in 1990, but the low rate of production increase has never sustainably alleviated the need for grain imports. Currently, Iran’s agriculture supplies about 90% of the domestic food demands but at the cost of consuming 92% of the available freshwater. In rough terms, the net value of agricultural import is equal to 14% of Iran’s current oil export gross revenue. Located in a dry climatic zone, Iran is currently experiencing unprecedented water shortage problems which adversely, and in some cases irreversibly, affect the country’s economy, ecosystem functions, and lives of many people. Te mean annual precipitation is below 250 mm in about 70% of the country and only 3% of Iran, i.e. 4.7 million ha, receives above 500 mm yr−1 precipitation.
The geographical distribution of Iran’s croplands shows that the majority of Iran’s cropping activities take place in the west, northwest, and northern parts of the country where annual precipitation exceeds 250 mm . However, irrigated cropping is practiced in regions with precipitations as low as 200 mm year−1 , or even below 100 mm year−1 . To support agriculture, irrigated farming has been implemented unbridled, which has devastated the water scarcity problem. The increase in agricultural production has never been able to keep pace with raising demands propelled by a drastic population growth over the past few decades, leading to a negative net international trade of Iran in the agriculture sector with a declining trend in the near past . Although justified on geopolitical merits, Iran’s self-sufficiency agenda has remained an issue of controversy for both agro-ecological and economic reasons. Natural potentials and constraints for crop production need to be assessed to ensure both suitability and productivity of agricultural systems. However, the extents to which the land and water resources of Iran can meet the nation’s future food demand and simultaneously maintain environmental integrity is not well understood. With recent advancement in GIS technology and availability of geospatial soil and climate data, land suitability analysis now can be conducted to gain insight into the capability of land for agricultural activities at both regional and global scales. Land evaluation in Iran has been conducted only at local, small scales and based on the specific requirements of a few number of crops such wheat, rice and faba bean. However, there is no large scale, country-wide analysis quantifying the suitability of Iran’s land for agricultural use. Herein, we systematically evaluated the capacity of Iran’s land for agriculture based on the soil properties, topography, and climate conditions that are widely known for their relevance with agricultural suitability. Our main objectives were to: quantify and map the suitability of Iran’s land resources for cropping, and examine if further increase in production can be achieved through agriculture expansion and/or the redistribution of croplands without expansion. The analyses were carried out using a large number of geospatial datasets at very high spatial resolutions of 850m and 28m .
Our results will be useful for estimating Iran’s future food production capacity and hence have profound implications for the country’s food self-sufficiency program and international agricultural trade. Although the focus of this study is Iran, our approach is transferrable to other countries,what is a vertical farm especially to those in the MENA region that are facing similar challenges: providing domestic food to a rapidly growing population on a thirsty land.We classified Iran’s land into six suitability categories based on the soil, topography, and climate variables known to be important for practicing a profitable and sustainable agriculture. These suitability classes were unsuitable, very poor, poor, medium, good, and very good . This classification provides a relative measure for comparing potential crop yields across different lands. Four major land uses that were excluded from the suitability analysis comprised 19.3 million ha of Iran’s land , leaving 142.8 million ha available for agricultural capability evaluation .When land suitability was evaluated solely based on the soil and topographic constraints , 120 million ha of land was found to have a poor or lower suitability ranks . Lands with a medium suitability cover 17.2 million ha whilst high-quality lands do not exceed 5.8 million ha . Te spatial distribution of suitability classes shows that the vast majority of lands in the center, east and, southeast of Iran have a low potential for agriculture irrespective of water availability and other climate variables . As shown in Fig. 2, the potential agricultural productivity in these regions is mainly constrained by the low amount of organic carbon and high levels of sodium contents . Based on soil data, Iran’s soil is poor in organic matters with 67% of the land area estimated to have less than 1% OC. Saline soils, defined by FAO as soils with electrical conductivity >4 dS/m and pH<8.2, are common in 41 million ha of Iran. Although many plants are adversely affected by the saline soils , there are tolerant crops such as barley and sugar beet that can grow almost satisfactorily in soils with ECs as high as 20 dS/m, which was used as the upper limit of EC in this analysis .Although sodic soils are less abundant in Iran , soils that only have high ESP covers ~30 million ha . We used an ESP of 45% as the upper limit for cropping since tolerant crops such as sugar beet and olive can produce acceptable yield at such high ESP levels.As shown in Fig. 2, EC is not listed among the limiting factors, while we know soil salinity is a major issue for agriculture in Iran. This discrepancy can be explained by the higher prevalence of soils with ESP>45% compared to those with EC>20 dS/m, which can spatially mask saline soils. Tat is, the total area of soils with EC>20 dS/m was estimated to be about 6.4 million ha , while soils exceeding the ESP threshold of 45 constituted ~12 million ha i.e. almost double the size of saline soils. Iran’s high-quality lands for cropping are confined to a narrow strip along the Caspian Sea and few other provinces in the west and northwest .
In the latter provinces, the main agricultural limitations are caused by high altitude and steep slopes as these regions intersect with the two major mountain ranges in the north and west .Thus far, the land suitability analysis was based on soil and terrain conditions only, reflecting the potential agricultural productivity of Iran’s without including additional limitations imposed by the water availability and climatic variables. However, Iran is located in one of the driest areas of the world where water scarcity is recognized as the main constraint for agricultural production. Based on aridity index, our analysis showed that 98% of Iran could be classified as hyper-arid, arid, or semi-arid . August and January are the driest and wettest months in Iran, respectively, as shown in Fig. 3. Over half of the country experiences hyper-arid climate conditions for five successive months starting from June . This temporal pattern of aridity index has dire consequences for summer grown crops as the amount of available water and/or the rate of water uptake by the crop may not meet the atmospheric evaporative demand during these months, giving rise to very low yields or total crop failure. It must be noted that the high ratio of precipitation to potential evapotranspiration in humid regions could also result from low temperature rather than high precipitation. There is a high degree of overlap between regions that experience wetter conditions for most of the year and those identified as suitable for agriculture based on their soil and terrain conditions . This spatial overlap suggests that some of the land features relevant to cropping might be correlated with the climate parameters. In fact, soil organic carbon has been found to be positively correlated with precipitation in several studies. To incorporate climate variables into our land suitability analysis, we used monthly precipitation and PET as measures of both overall availability and temporal variability of water. We derived, from monthly precipitation and PET data, the length of the growing period across Iran . Growing period was defined as the number of consecutive months wherein precipitation exceeds half the PET. As shown in Fig. 3, areas where moisture conditions allow a prolonged growing period are predominately situated in the northern, northwestern, and western Iran with Gilan province exhibiting the longest growing period of 9 months. For over 50% of the lands in Iran, the length of the moist growing period is too short to support any cropping unless additional water is provided through irrigation . However, these areas, located in the central, eastern, and southeastern Iran, suffer from the shortage of surface and groundwater resources to support irrigated farming in a sustainable manner. Taking into account daily climate data and all types of locally available water resources can improve the accuracy of the length of growing period estimation.