Expansion Of Irrigated Areas Research Articles

Assessment of catchment water resources allocation under climate change in Luwombwa sub-catchment, Zambia

The uncertainty in climate change and high water demand pose pressure on the natural water resources supply. Not only does this require better understanding but also a call for immediate interventions, mitigation and adaptive measures. This study evaluates catchment water resources in the Luwombwa sub-catchment in Zambia through statistical analysis in the downscaling of past, present and future climatic variables from the CMIP6 climatic model. These variables are then integrated into WEAP - a semi-distributed hydrological and water evaluation model - to perform water demand and allocation scenario modelling. Mult-site calibration and validation were conducted on five selected micro-catchments within Luwombwa sub-catchment. The model performance was assessed usng the R2, NSE and PBIAS as the objective functions. Satisfactory values of 92 % for R2, 82 % for NSE and 6.9 % for PBIAS were achieved. This allowed for scenario modelling on water demand and allocation among competing users. Three future scenarios (2022–2050) were developed from the historical to baseline (1988–2022) and included state of water resources availability under climate change, expansion of irrigation area and impact of dam construction in the sub-catchment. The study reveals a decrease of 20 % in sub-catchment's water availability resulting from 9.3 % (equivalent to 4oC) rise in maximum temperature and 4.5 % reduction in rainfall within the entire sub-catchment. This is especially under the persistence of SSP370 climate variability scenario projections downscaled from four GCM models by the year 2050. The study further revealed that the change point for anticipated future climate extremes is likely to occur between 2027 and 2030. The results are indicative of downward trends in streamflow under climate change and socioeconomic development leading to increase in water value and water scarcity. The insights from the study are critical to inform formulation of effective catchment water resources management strategies such as the development of management plans and adapation measures in the face of climate change and the needs for different stakeholders involvement.

Assessing sustainable development pathways for water, food, and energy security in a transboundary river basin

Worldwide hundreds of millions of people suffer from water, food and energy insecurity in transboundary river basins, such as the Zambezi River Basin. The interconnected nature of nexus is often not recognized in investment planning and many regional policymakers lack adequate tools to tackle it. Future growing demands and climate change add an additional challenge. In this study, we combine policy relevant co-developed stakeholder scenarios and integrated nexus modeling tools to identify key solutions to achieve sustainable development in the Zambezi. Results show that siloed development without coordination achieves the least economic and social benefits in the long term. Prioritizing economic benefits by maximizing the use of available natural resources results in the expansion of irrigated areas by more than a million hectares and increase in hydropower production by 22,000 GWh/year in the coming decades, bringing significant economic benefits, up to $12.7 billion per year, but causes local water scarcity and negative impacts on the environment. Combining environmental protection policies with sustainable investments of $7.2 billion per year (e.g. groundwater pumping and wastewater treatment and reuse, irrigation efficiency improvements, and farmer support aimed to improve food security and productivity) results in significantly higher social benefits with economic benefits that still reach $11.7 billion per year.

Long‐Term Monitoring of the Annual Irrigated Cropland Extent in Fragmented and Heterogeneous Arid Landscapes Using Machine Learning and Landsat Imagery

AbstractUnderstanding the long‐term spatiotemporal evolution of irrigated cropland is essential for water resource management, but this knowledge remains elusive in most water‐stressed arid areas. In this study, we introduced an integrated framework for long‐term and field‐scale mapping of annual irrigated cropland in arid and semiarid regions. This framework combines the k‐means algorithm with a semiautomatically trained random forest classifier for initial classification and employs the Bayesian Updating of Land Cover algorithm for subsequent postprocessing. Taking the Heihe River basin in northwestern China as the experimental area, we generated 30‐m annual irrigated cropland maps spanning from 1990 to 2020 based on Landsat imagery and the Google Earth Engine. Comprehensive validation confirmed the reliability of this approach, with the overall accuracy of the annual maps ranging from 83% to 88.3% (mean: 86.6%). Our data set provides an unprecedentedly long‐term and fine‐scale perspective for understanding the continuous spatial and temporal dynamics of irrigated cropland in the Heihe River basin, surpassing previous studies in Central Asia and northwestern China. Notably, a rapid expansion of irrigated areas is occurring in the basin, especially in the water‐stressed midstream and downstream areas. This finding points to potential ecological risks in the foreseeable future due to water resource constraints.

Irrigação com águas salinas e aplicação foliar de H2O2 altera a homeostase iônica do maracujazeiro-azedo

ABSTRACT Qualitative and quantitative scarcity of water sources is a reality in the Brazilian semi-arid region and restricts the expansion of irrigated areas in this region, where high levels of soluble salts are common. Thus, it is extremely important to seek strategies to enable the production of fruit crops such as sour passion fruit. In this context, the objective of this study was to evaluate the levels of NPK, Na+ and Cl- in leaf and stem tissues of sour passion fruit cv. BRS Rubi do Cerrado as a function of irrigation with saline water and exogenous application of hydrogen peroxide. The experiment was carried out in drainage lysimeters under greenhouse conditions in Campina Grande, PB, Brazil. The design was completely randomized in split plots, with five levels of electrical conductivity of water - ECw (0.6, 1.2, 1.8, 2.4 and 3.0 dS m-1) considered plots and four concentrations of hydrogen peroxide – H2O2 (0, 15, 30 and 45 µM) considered subplots, with three repetitions. Sodium content in the leaves decreased when the H2O2 concentration of 45 µM was applied. N/P and N/Na ratios in the leaves of sour passion fruit cv. BRS Rubi do Cerrado decreased with the increase in irrigation water salinity from 2.76 and 2.03 dS m-1, respectively. Chloride content in the leaves of sour passion fruit increased as a function of irrigation water salinity, regardless of H2O2 application.

Spatial adaptation pathways to reconcile future water and food security in the Indus River basin

Irrigated wheat production is critical for food security in the Indus basin. Changing climatic and socio-economic conditions are expected to increase wheat demand and reduce irrigation water availability. Therefore, adaptation of irrigated wheat production is essential to achieve the interlinked Sustainable Development Goals for both water and food security. Here, we developed a spatial adaptation pathways methodology that integrates water and food objectives under future climate change and population growth. The results show that strategic combinations between production intensification, laser land leveling, and targeted expansion of irrigated areas can ensure wheat production increases and irrigation water savings in the short term. However, no adaptation pathways can ensure long-term wheat production within the existing irrigation water budget under rapid population growth. Adaptation planning for the Sustainable Development Goals in the Indus basin must therefore address both climatic and population changes, and anticipate that current food production practices may be unsustainable.

Small and medium-sized businesses in agricultural sector on the example of the Almaty region of the Republic of Kazakhstan

In a market economy, tough competition, the urgent task is to ensure the effective functioning of the agro-industrial business, which creates a social and economic basis that allows to maintain a rural lifestyle, develop rural areas, responding flexibly and in a timely manner to changing supply and demand conditions. The goal is to study the current state of entrepreneurship in the agro-industrial complex of the Almaty region, the pace of development and the effectiveness of support measures. Methods – economic-statistical, monographic, abstract-logical, comparative analysis and synthesis. Results – analyzed the number of operating small and medium-sized agribusiness entities in this region over the past 5 years, the number of employees employed in this area, the gross agricultural output in the country, as well as in the context of districts. An analysis was made of the share of small and medium-sized enterprises (SMEs) in agricultural production in general in Kazakhstan and the Almaty region, in particular. The main problems and ways to solve them are outlined. The indicators of objects of entrepreneurial activity, the volume of output of goods in agricultural sector and their structure in the region according to statistical data for 2018-2022 are presented. Shows the amount of state financial assistance at the regional level in recent years. Conclusions – on the GDP of agricultural sector over a five-year period, on average, SME accounts for 28.5%, individual entrepreneurs 5.3%, PPF 66.2%. The issues of irrational use of agricultural land, expansion of irrigated areas, regulatory support for the effective use of allocated public funds, insufficient institutional support for rural entrepreneurs are considered.

Recent Decline of Irrigation‐Induced Cooling Effect Over the North China Plain in Observations and Model Simulations

AbstractIrrigation over the North China Plain (NCP) has been demonstrated to lower temperature by altering the surface energy budget. During past decades, the concurrence of irrigated area variation and reduced irrigation intensity prompted our investigation into whether there has been a temporal change in irrigation cooling effect over the NCP, which is largely unknown. Using historical observations in 1979–2018, we detect a shift in the cooling effect occurring around 1995, when the expansion of irrigated area was going to slow down and water‐conserving irrigation technology was boomingly introduced. After this time, the accelerated process of cooling effect (−0.0045°C year−1) switches to a decelerated one (0.0089°C year−1). Regional climate simulations also show a pronounced slowdown in irrigation‐induced cooling with the rate of 0.0081°C year−1. The irrigation‐induced cooling is expected to be weaker with the persistent reduction in agricultural water use and contribute to a more rapid warming.

Ecological safety of water resources in Khujand (Tajikistan) area, in the development context of agricultural activities

The research deals with investigation of relation between agricultural activity and ground water, surface water composition and quantity. The area of investigation is under huge increases in water consumption and active development of agricultural and economic activities. On the one hand, the agricultural complex uses groundwater and thereby reducing the level of groundwater, on the other hand, the irrigation system causes the development of a desalination zone to the depths of groundwater. Anyway, the influence into the groundwater is obvious. In the article has analyzed the relationship of surface and groundwater, hydraulically connected. It was studied the expansion of irrigation area contributes to the irrigation water flow strengthening into the rivers, also to the groundwater flow.

Does agricultural water conservation policy necessarily reduce agricultural water extraction? Evidence from China

Does the implementation of agricultural water conservation policy necessarily bring about a reduction in agricultural water extraction? Taking China's National Agricultural Water Conservation Outline proposed in 2012 as an example, this paper uses the data of 31 provinces from 2000 to 2019, and employs an empirical strategy of Difference-in-Differences (DID) to estimate the impact of the agricultural water conservation policy on agricultural water extraction. The results show that the agricultural water conservation policy does not achieve the decline of agricultural water extraction, but increases agricultural water extraction. When addressing contemporaneous water-related policies or estimating in subsample, these results are robust. The possible reason for this phenomenon is that the agricultural water conservation policy promotes agricultural production, especially by increasing the sown area and irrigated area, and the expansion of irrigated area is the main reason for the increase in agricultural water extraction. Moreover, land potentiality for crop production may affect the water-saving effect of the agricultural water conservation policy, in which provinces with higher land potentiality will have less increase in agricultural water extraction caused by the agricultural water conservation policy. Therefore, with the empirical evidence from China, agricultural water conservation policy may not necessarily reduce agricultural water extraction, and this phenomenon is always regarded as rebound effects. In order to avoid the adverse impacts of the rebound effect, agricultural water-saving technologies can be strengthened in areas with high land potentiality for agricultural production, and market-oriented policies, such as water rights reform, can be employed to avoid excessive use of water resources in areas with severe over-extraction.

IrriMap_CN: Annual irrigation maps across China in 2000–2019 based on satellite observations, environmental variables, and machine learning

Agricultural irrigation, as an important practice to protect crops from drought and promote grain yield, has a long history in China. A timely and precise dataset about the extent and dynamics of irrigated areas is necessary for water allocation and agricultural management but is scarce in China. Here we developed annual irrigated cropland maps across China (IrriMap_CN) at 500-m resolution from 2000 to 2019, using MODIS data, machine-learning method, and Google Earth Engine platform. First, we generated annual nationwide training samples by strictly screening the existing irrigation maps downscaled from the statistical data. Second, we implemented locally adaptive random forest classifiers in 511 nominal 1° × 1° grid cells across China with MODIS vegetation indices, climatic factors, and topography variables. Third, we conducted nationwide pixel-wise validation of the IrriMap_CN using independent samples. The validation results based on more than 3000 ground truth points revealed that IrriMap_CN had high accuracies ranging from 77.2% to 85.9%. The time series of IrriMap_CN detected substantial expansion of irrigated areas in Xinjiang and Heilongjiang (more than 50% in total) and pronounced decreases in Sichuan, Jiangsu, and Hebei. The analyses of irrigation frequency, start time, and end time implied that North China Plain was the most intensive irrigated area; but the irrigation area showed a decreasing trend since 2000, consistent with the reduced agricultural water consumption. The annual irrigation datasets allow us to understand the spatiotemporal dynamics of irrigated croplands in China and are expected to contribute to the improvement of earth system models and facilitate sustainable agricultural water management.

An integrated approach for the application of geographical information system and Remote Sensing for prospective groundwater zones in Surat region, India

Sustainable groundwater management is becoming a priority in the context of significant changes in groundwater use patterns, particularly with continuously increasing demand for groundwater due to growing population, expansion of irrigation area, and economic progress. This research contributed to the integration of GIS-RS and a fuzzy technique to delineate groundwater prospective zones for Surat district, India. In this study, nine different fuzzy membership layers of influencing parameters were overlaid using the fuzzy GAMMA operator to generate the prospective zones. The result indicates that 62.53% area of the district falls under the high prospective zone. Sensitivity analysis reveals that lineament density, rainfall distribution, and geomorphology were the most important parameters influencing the region's groundwater potentiality. The RS-GIS-based Fuzzy method is proficient and efficient and can be applied anywhere on the earth to identify and delineate groundwater prospective zones.

A Quantitative Review of Irrigation Development in the Yazoo–Mississippi Delta from 1991 to 2020

The Yazoo–Mississippi Delta is one of the regions within the Lower Mississippi River Basin where substantial irrigation development and consequent groundwater depletion have occurred over the past three decades. To describe this irrigation development, a study was conducted to analyze existing geospatial datasets and to synthesize the results with those of past government surveys. The effort produced a quantitative review characterizing three aspects of irrigation development from 1991 to 2020. First, the expansion of irrigated area was tracked in terms of absolute area and in terms of fraction relative to total land or cropland area. Second, trends in irrigated land cover were traced in terms of irrigated crop mix, irrigated fractions of main crops, and comparisons with non-irrigated land. Third, changes in irrigation systems were examined in terms of water sources, energy sources, and application methods. Original findings of this study for the end of 2020 included moderate positive spatial autocorrelation in the density of irrigated areas; a higher irrigated crop preference for soybean and rice over cotton and corn in highly hydric soils; and 91% and 3% of permitted areas studied being respectively under groundwater withdrawal permits exclusively and under surface water diversion permits exclusively. By compiling such information, this paper can serve as a convenient reference on the recent history and status of irrigation development in the Yazoo–Mississippi Delta.

On‐farm irrigation water management in India: Challenges and research gaps*

AbstractThe growing demand for food to feed the increasing population of India has made it necessary to bring more land under cultivation with assured irrigation facilities. The irrigation sector demands a high amount of the available freshwater resources of the country. Thus, the efficiency of its use is of utmost importance for sustainable agriculture. India is the second‐largest irrigated country and is one of the leading countries in terms of the expansion of irrigated areas in the world. Researchers and various agencies are working towards increasing the irrigation efficiency of the system and the water productivity of the crops. The formulation of any irrigation scheme and policy to be sustainable should be based on scientific inputs and supported by pertinent research studies. The effective communication between policymakers and the research community is the main key to the success of such formulated schemes and policies. This paper provides an overview of current challenges and problems associated with irrigation at the field level vis‐à‐vis research gaps for scientific management of irrigation water in the farmer's field. The apathy of farmers for adopting modern irrigation practices has also been reasoned in this review paper. This review paper would provide an insight into common irrigation‐related problems of farmers to researchers and policymakers.

A Study on Expansion Possibilities of Irrigated Areas in Uluırmak Irrigation Basin and Production Planning According to Water

In this study, it is aimed to determine the current irrigation management and performance data in Uluırmak irrigation, to investigate the possibilities of expanding the irrigated areas in the network, and to calculate the optimum production patterns of agricultural enterprises. This study was carried out in 1995 and the results of this study were comparatively reviewed between 1995 and 2020 years. The data used in the study consists of primary data obtained from the surveys conducted with face-to-face interviews with a total of 72 enterprises in the region, determined by stratified sampling method. Linear programming method was used to determine the optimum production patterns according to the current situation in the irrigation basin and the expansion of irrigated areas. The average width of the farmland in the region is 74.42 decares (da), 47.75 da of which is irrigated agricultural land. After the planning made in accordance with the current conditions in the enterprises examined, wheat came to the plan with a maximum of 20.92 da, respectively, sugar beet (9.87 da), sunflower (5.89 da), beans (4.78 da), alfalfa (2.78 da), vegetables (2.89 da), and barley (1.12 da). In addition, the total gross profit of the enterprise reaches 445.4 TL, with 2.29 dairy cows (cultural hybrid) and 18.95 sheep coming to the plan in planned production. In case of the completion of the missing investments in the irrigation network and the expansion of the irrigated lands, the irrigated lands will increase by 33.33% and the gross profit will increase by 60.48% compared to the current situation and reach 472.4 TL. One of the important results of the study is that the average irrigated field land, which is 47.75 da, has increased to 64.20 da (34.45%) with the expansion of irrigated lands and planned water use.

Delineation of groundwater potential zones using modified weight standardization method and GIS in arid environments: case study of Ejina Oasis, Inner Mongolia, China

Groundwater refers to a vital resource for sustainable development of the earth. As fueled by the economic development, population growth, and the expansion of irrigation area, groundwater has been increasingly demanded. It is noteworthy that groundwater seriously limits the sustainable development in the arid desert areas of Africa and Asia. To tackle down this issue, modified weight standardization (MWS) and improved fuzzy analytic hierarchy process (IFAHP) theories and geographic information system (GIS) were adopted to find the groundwater potential zones (GWPZ) in the Ejina Oasis of northwestern China. A range of thematic layers (i.e., lithology, lineament density, soil moisture, normalized difference vegetation index, rainfall, biomass, drainage density, slope, elevation, and land use/land cover) were built with the existing maps and the remote sensing data. The mentioned thematic layers were standardized using MWS. Subsequently, the IFAHP was adopted to assign weight to the thematic layers. Lastly, all the layers were integrated in GIS to map the GWPZ. The MWS-IFAHP–based groundwater potential map revealed four categories: “excellent” (13.91%), “good” (21.97%), “moderate” (34.79%), and “poor” (29.33%). As indicated from the validation of the results, GIS-based MWS and IFAHP technologies can be used to effectively generate groundwater potential map under an accuracy of 80%. The results of this study are critical to plan and develop scarce groundwater resources in arid areas efficiently at a low cost, which can ensure sustainable water supply in the future.

Financial Feasibility of Water Conservation in Agriculture

AbstractGlobal water use for food production needs to be reduced to remain within planetary boundaries, yet the financial feasibility of crucial measures to reduce water use is poorly quantified. Here, we introduce a novel method to compare the costs of water conservation measures with the added value that reallocation of water savings might generate if used for expansion of irrigation. Based on detailed water accounting through the use of a high‐resolution hydrology‐crop model, we modify the traditional cost curve approach with an improved estimation of demand and increasing marginal cost per water conservation measure combination, adding a correction to control for impacts on downstream water availability. We apply the method to three major river basins in the Indo‐Gangetic plain (Indus, Ganges and Brahmaputra), a major global food producing region but increasingly water stressed. Our analysis shows that at basin level only about 10% (Brahmaputra) to just over 20% (Indus and Ganges) of potential water savings would be realized; the equilibrium price for water is too low to make the majority of water conservation measures cost effective. The associated expansion of irrigated area is moderate, about 7% in the Indus basin, 5% in the Ganges and negligible in the Brahmaputra, but farmers' gross profit increases more substantially, by 11%. Increasing the volumetric cost of irrigation water influences supply and demand in a similar way and has little influence on water reallocation. Controlling for the impact on return flows is important and more than halves the amount of water available for reallocation.

Environmental impacts of land management on the sustainability of natural resources in Oriental Erg Tunisia, North Africa

In southwestern Tunisia, the intense exploitation of the natural resources (soil, water, hydrocarbons, etc.) bears unrecoverable consequences on the local environment. In fact, the harsh climate conditions, the expansion of irrigated areas (date plantation and greenhouses) and the overexploitation of water resources in these ecologically fragile lands increase understandably desertification in the Kebili field. The field observations in the study indicate that the sustainability of natural resources is threatened, besides increasing soil salinization and water degradation. The used water quality indexes (BCWQI, OWQI and WAWQI) indicate that more than 55% of the samples are unsuitable for domestic consumption and irrigation purposes. The contamination of the CI water and the agricultural lands by crude mature organic matter is confirmed by the elevated concentrations of organic compounds that range between 1.8 and 16 mg/L in the sampled waters, while they reach the 80 mg/L in the surface horizon in the oases in Mazraa Neji and Oum El Fareth areas. The sensitivity of the study area to different processes of land degradation is evaluated by two multi-criteria models (MEDALUS and IMDPA), which indicate high to very high risks of environmental degradation in the study area with an average geometric mean of 1.67 and 2.8, respectively. Given the potential relevance of the contamination and its long-term impacts on the healthy environmental functioning, this paper outlines the main baselines aspects, the rehabilitation measures and the decontamination actions that should be taken in account in the planning of the most adopted management projects.

IRRIGATION WITH SALINE WATER AND SILICATE FERTILIZATION IN THE CULTIVATION OF ‘GIGANTE AMARELO’ PASSION FRUIT1 2

ABSTRACT The Brazilian Northeast region suffers from some abiotic stresses that are responsible for the loss of agricultural production, such as long drought periods and high evapotranspiration, associated with the quality of the water, which induces the use of saline water as an alternative for the expansion of irrigated areas, and silicate fertilization contributes to reduce the effects of salinity under the Northeastern semi -arid conditions. The objective of this study was to evaluate the osmotic potential and physiological indices of yellow passion fruit seedlings under irrigation water salinity and silicate fertilization. The experiment was carried out under greenhouse conditions at the Federal University of Campina Grande, Pombal -PB, Brazil, in a randomized block design in a 5 x 5 factorial scheme, relative to five levels of electrical conductivity of irrigation water - ECw (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) and five doses of silicate fertilization (0; 25; 50; 75 and 100 g silicon per plant) in four replicates and two plants per plot. The application of 50, 75 and 100 g silicon per plant reduced the osmotic potential in the leaf tissues of ‘Gigante Amarelo’ passion fruit plants. Water salinity lower than 1.3 dS m-1 resulted in an increase in chlorophyll b content; increase in carotenoid content was observed in plants subjected to silicon doses of 25 and 100 g per plant. Salinity levels above 1.1 dS m-1 compromised the performance of photosystem II of passion fruit plants when subjected to silicon doses.

Substantial decline in atmospheric aridity due to irrigation in India

Compound extremes of soil moisture (SM) drought and high vapor pressure deficit (atmospheric aridity) are disastrous for natural and social systems. Despite a significant expansion in irrigated area in India, the role of irrigation on SM and atmospheric aridity is not examined. We used observations, reanalysis datasets, and high-resolution simulations from the Weather Research and Forecasting (WRF) model to show that irrigation significantly modulates SM and atmospheric aridity in India. The Indo-Gangetic Plain, which is one of the most intensively irrigated regions in the world, experienced significant (P-value = 0.03) cooling (∼0.8 °C) and an increase in solar-induced chlorophyll fluorescence during the crop growing season (November–February). Atmospheric aridity has significantly (P-value = 0.0002) declined (−1.38 kPa) while SM (1.6 m3 m−3) and relative humidity (RH) (2.0%) have increased over the Indo-Gangetic Plain during 1979–2018. We conducted high-resolution simulations using the WRF model to examine the role of irrigation on atmospheric aridity. Irrigation strongly modulates SM drought and atmospheric aridity by increasing latent heat and RH and reducing sensible heat. Our findings have implications as irrigation can influence compound extremes of SM drought and atmospheric aridity. Climate models need to incorporate the influence of irrigation for reliable projections in the intensively irrigated regions.

Physiological indices and growth of ‘Gigante Amarelo’ passion fruit under salt stress and silicate fertilization

ABSTRACT Abiotic stresses are responsible for the loss of agricultural production in different regions, especially in semiarid regions, which have long periods of drought and high evapotranspiration, leading to the use of saline water as an alternative for the expansion of irrigated areas. In this context, the objective was to evaluate the physiological indices and the growth of the ‘Gigante Amarelo’ passion fruit as a function of the salinity of irrigation water and fertilization with silicon. A randomized block design was used in a 5 x 2 factorial scheme, whose treatments consisted of five electrical conductivities of irrigation water - ECw (0.3; 1.0; 1.7, 2.4 and 3.1 dS m-1) associated with two doses of silicion (150 and 300 g of silicon plant-1) with four repetitions. Salt stress causes changes in gas exchange, chlorophyll a and b synthesis and growth of ‘Gigante Amarelo’ passion fruit plants, 60 days after transplanting. Fertilization with silicon dose of 300 g plant-1 promotes increments in CO2 assimilation rate and instantaneous water use efficiency, being able to mitigate the deleterious effects of salinity. Passion fruit plants fertilized with silicon dose of 300 g plant-1 attained greater growth in stem diameter and relative growth rate in stem diameter, from 30 to 60 days after transplanting.