Initial Development of Safflower Submitted to Irrigation Water Salinity Levels

Safflower cultivation is an alternative to tropical cropping systems, with a good rusticity and some tolerance to saline stress in some cultivars. With the increase of irrigated areas around the world, salinization of the soil is an inherent concern, being the management of irrigation and cultivated species fundamental. The objective of this study was to evaluate the growth and initial development of safflower culture submitted to irrigation water salinity levels. The experiment was carried out in a greenhouse in a completely randomized design consisting of five irrigation water salinity levels (0, 2, 4, 6 and 8 dS m) and six replications. The saline solution was prepared using NaCl and measured with a conductivity meter. Plant height, number of leaves and stem diameter at 26 and 41 days after emergence, and shoot dry weight were evaluated; root volume; root dry mass; total dry mass and dry root/shoot mass ratio at 41 days after plant emergence. There was no visual influence of salinity levels in the evaluations at 26 days after plant emergence. However, 41 days after plant emergence, the increase in salinity levels promoted a decrease in all analyzed variables, except for root volume. Safflower does not tolerate irrigation with saline water. The damages occur from 2 dS m, but the largest reductions in the initial development of safflower occur from 6 to 8 dS m.


Introduction
Brazil is a country with great expressiveness in the agricultural sector, being a worldwide highlight in food production, considered an important country for food security in the future (Hertel, 2015).Socio-climatic characteristics and their vast territory allow large-scale agriculture and livestock production, with emphasis on the production of oilseeds, cereals, and fibers exported to various regions of the world as well as horticulture, characterized by family farming (Goedert, 1989).However, it is perceived that for the maintenance of this scenario it is necessary to diversify production in the regions, aiming at the socioeconomic and environmental sustainability of the agricultural sector.Specifically, in the Brazilian Central West, in general, soybeans, corn, and cotton are grown in the harvest and/or the second crop, and in some regions sugar cane.Thus, research on the adaptability of other species as an alternative to cultivation in the region, such as wheat (Triticum aestivum) (Freitas et al., 2018) in the State of Goiás, Mato Grosso and Mato Grosso do Sul, and the safflower (Carthamus tinctorius L.) in the State of Mato Grosso (Anicésio et al., 2018;Bonfim-Silva et al., 2018).
Safflower develops rapidly, and its seeds come to produce a high quality, high added value oil widely used in the food and cosmetic industry.In this sense, safflower cultivation can become an alternative to cultivation in the Brazilian Cerrado both in rainfed systems (first and second harvests) and irrigated (winter) systems.
According to the latest survey conducted by the National Water Agency in 2015, Brazil has an irrigated area of 6.95 million hectares, with a potential increase of 45% by the year 2030.Among all the regions, the Central West has the greatest effective potential for expansion, 32% according to the agency (ANA, 2017).
In these regions, an increase in the number of irrigated crops is possible, allowing up to three harvests per year, which perhaps can cause damages concerning soil salinization associated with the improper management of the system, de China eval cases with increase in Thus, the o salinity lev

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The soil u arable laye granulome   The accum characteris consequen componen The    The dynamics of accumulation of salts in the soil varies between years and is dependent on the management used so that the effects can be minimized with the rainy period between two crops depending on the region.In a study evaluating the impact of irrigation with three levels of saline water on wheat cultivated in the winter in China, it was verified the return in the electrical conductivity of the soil to normal levels after a rainy season (Wang et al., 2015).
One of the main effects of salinity is osmotic stress, due to the reduction of soil water potential, reduces the absorption of water and nutrients, directly reflecting the water status of the plant.The energy expenditure for the uptake of water through biochemical adjustments is one of the initial factors for the reduction of growth due to osmotic stress (Hussain et al., 2016).
In addition, under specific conditions, salinity has an effect on photosynthesis.Research has shown a significant decrease of the photosynthetic rate under conditions of high vapor saturation deficit (high atmospheric demand) and high salinity in cucumber (Cucumis sativus) cultivation, thus reducing plant growth and development (Shibuya et al., 2018).
The increasing levels of salinity in the irrigation water applied in the safflower culture negatively influenced the characteristics evaluated, reducing their expression as the salinity levels were increased.

Conclusions
The salt level of 8 dS m -1 in irrigation water reduced the total dry mass of safflower plants (Carthamus tinctorius L.) by 68%.
The salinity of irrigation water causes reductions in the growth and development of safflower plants (Carthamus tinctorius L.), mainly at levels between 6 and 8 dS m -1 .