Tuesday, 15 December 2020

Lupine Publishers | Salinity and Sodicity Shock Quiona Plant Establishment

  Lupine Publishers | Current Investigations in Agriculture and Current Research


Abstract

A possible alternative to minimize the effects of salt stress is the introduction of species tolerating these conditions with a good adaptability in terms of growth and yield. So, quinoa (Chenopodium quinoa Willd.) cultivar Titicaca was grown. In view of that a pot experiment was conducted to study the growth performance and ionic composition of Conocarpus erectus L. under saline – sodic conditions. Sixteen treatments i.e. (T1=<4(dSm-1)+<15 (mmol L-1)1/2, T2= 20(dSm-1) + 20 (mmol L-1)1/2, T3= 20(dSm-1)+40 (mmol L-1)1/2, T4= 20 (dSm-1)+60(mmol L-1)1/2, T5= 20(dSm-1)+80(mmolL-1)1/2, T6= 20(dSm-1)+100 (mmol L-1)1/2, T7= 30(dSm-1)+20(mmol L-1)1/2, T8= 30(dSm-1)+40(mmol L-1)1/2, T9= 30 (dSm-1)+60(mmol L-1)1/2, T10=30(dSm-1)+80(mmolL-1)1/2, T11=30(dSm-1)+100(mmolL-1)1/2, T12=40(dSm-1)+20(mmolL-1)1/2, T13=40(dSm-1)+40(mmol L-1)1/2, T14=40 (dSm-1)+ 60(mmol L-1)1/2, T15=40 (dSm-1)+80(mmol L-1)1/2 and T16=40(dSm-1)+100 (mmol L-1)1/2) were evaluated in order to investigate their effect on plant growth and yield. T1 attained the highest plant height (80cm) due to having low saline sodic stress. Increased saline sodic stress decreased plant height (44.7cm) and got the bottom position. % decrease over control in plant height was also differed among treatments. This percentage was ranged from 1.25 to 44.12 due to variations in saline sodic stresses. The reduction in grain yield was addressed by the toxic effects of salts in saline sodic soils. 4.90 % decrease over control in grain yield by T2 while T16 produced the increased % decrease over control in grain yield (73.06). Similar trend was also observed in straw yield

Keywords: Salinity/Sodicity; Quinoa; Growth; Yield

Introduction

Salt affected area throughout the world is estimated at over 800 million hectares [1]. In Turkey, there is salinity problem in 1.5 million hectares of soils due to improper management of irrigation and inadequate drainage [2]. As a result of unsustainable and faulty agricultural practices, a considerable amount of agricultural land is put out of production each year. Increased salinization of arable land is expected to cause a land loss of 50% in 2050 [3]. Salinity and drought are two main environmental factors determining plant productivity and distribution of most major crops [4]. Soils are classified as saline when the electrical conductivity of a saturated paste (ECe) is 4 dS m-1(40 mM NaCl) or more [5]. So, over 6% of the global land area is affected by salt [6]. Salinity inhibits plant growth in two ways: first, it reduces the ability of plants to take up water (osmotic or water-deficit effect); second, excess salt in the transpiration stream causes injury to cells in the transpiring leaves (salt-specific or ion-excess effect). In the same context, Munns [7] confirmed that, plants respond to salinity stress in two phases: a rapid response to the increase in external osmotic pressure (starts immediately after the salt concentration around the roots increases to threshold levels, which decrease the new shoot growth) and a slower response due to the accumulation of Na+ in leaves (salt accumulation to toxic concentrations and increase senescence of older leaves). Salinity is one of the significant problems commonly observed among irrigated agricultural lands. Nowadays it is showed that salinity soils affect between 20 and 50% of irrigated arable lands worldwide [8]. Because of natural causes such as Irrigation water, soil structure, regional factors and some human activities, growth retardation and yield loss owing to salinity of soils is a common problem all over the world as most crop plants [7]. One option is the use of halophytic crop species, which can tolerate high levels of soil salinity. Many members of the family Chenopodiaceous are classified as salt tolerant one member of this family, quinoa (Chenopodium quinoa Willd) is able to grow on salinity soils [9].

The progressive salinization of irrigated land is a major environmental threat for crop production. Therefore, the selection and characterization of salt-resistant species are important to ensure future productivity of the arid and semi-arid agricultural regions [10] and it has garnered much attention around the world in recent years [11,12]. This interest based on not only its stress tolerance especially salinity soil condition, but also its nutritional quality especially high essential amino acid rates [13]. The main use of quinoa is for people such as cooking, baking, and various products for allergic to gluten and for animals such as feed, green fodder and for regulate plant growth with contains some phytohormones [14]. For these reasons, the year 2013 was declared “International Year of Quinoa” by the UN Food and Agriculture Organization (FAO) to focus attention on this crop worldwide [15]. Plants develop defense strategies against salt stress based on the activation of the ion transport system, osmotic adjustment and induction of antioxidant enzymes [16]. The capability of seedling establishment under saline conditions is dependent on cultivar [17]. Even though halophytic crop species are resistant against salinity levels into the soil, it has been shown in several studies that even halophytes are relatively sensitive to salinity during the stages of germination and seedling period [18]. Quinoa (Chenopodium quinoa Willd) has adapted to different agro-ecological zones range from sea level up to 4000 m altitude with its rich genetic diversity [19].

The United Nations Food and Agriculture Organization (FAO) declared 2013 as the “International Year of Quinoa” with the main objective to focus world attention on the role that quinoa’s biodiversity and nutritional value play in food security [20]. Quinoa has been indicated as a good candidate to offer food security, especially in the face of the predicted future world scenario of increasing salinization and aridity [21]. In recent years, it has attracted interest all over the world and quinoa cultivation has begun expanding in many countries in Europe, Africa and Asia [22]. Quinoa is an annual herbaceous, dicotyledonous crop species belonging to the C3 group of plants [23]. It has been cultivated in the Andean region of Bolivia and Peru over a period of 5000 years [24,25]. The panicle consists in small flowers producing one seed per flower [26]. Seed color varies from white, yellow, red to black depending on cultivars. The 1000 grain mass is generally low (3- 6g) due to the small seeds [27]. At the same time, quinoa is well adapted to grow under unfavorable soil and climatic conditions [19]. It has been cultivated on various types of soils including quite poor, saline or inadequately drained marginal soils with a wide pH range from 4.8 to 8.5 in Bolivian salt flats [28]. Quinoa shows exceptional adaptation to harsh environments such as drought and salinity [29]. Soil salinity reduces crop yields and is a worldwide problem. In the United States, approximately 2.2 million hectares of cropland in 48 States were occupied by saline soils, while another 30.8 million hectares are at risk of becoming saline (United States Department of Agriculture) [5]. Drought and salinity are common adverse environmental factors that affect the growth of plants and are considered as the main factors determining the global geographic distribution of vegetation and restriction of crop yields in agriculture [30,31].

Desertification and salinization are rapidly increasing on a global scale declining average yields for most major crop plants by more than 50 % [32]. Chenopodium spp. have been cultivated for centuries as a leafy vegetable (Chenopodium album) as well as an important subsidiary grain crop (Chenopodium quinoa and C. album) for human and animal food stuff due to high-protein and essential amino acids [33], a wide range of vitamins (A, B2, E) and minerals (Ca, Fe, Cu, Mg, Zn) [13]. Although, quinoa grains do not contain gluten and thus, they cannot be used alone for bread- making. However, they can be mixed with wheat flour in the preparation of bread with high nutritional value [34]. Accordingly, quinoa has been selected by the food and agriculture organization (FAO) as one of the crops destined to offer food security in the 21st century [11]. Several studies showed that even halophytes are particularly salt sensitive during the stages of seed germination and seedling establishment [35,36]. However, they have an advantage over plant species that lack strategies to deal with salt in the soil [37]. Salinity tolerance is a heritable trait with a polygenic character linked to a complex genetic basis that can be used as an efficient criterion for selection of salt resistant populations [38]. There is also evidence to support the view that salt tolerance is a complex physiological trait affecting entirely the plant’s life [39]. In addition, the quinoa plant is reported to be tolerant to drought [40], and also resists frost before the flower-bud formation stage [41] and salinity [17,42].

However, the definition of indicators that plant breeders might apply in open field to improve quinoa, for its tolerance or adjustment to saline environments, is still a matter of debate [43]. Quinoa a grain crop belongs to Amaranthaceae family with superior nutritional profile, originated from Andean region of Latin America where its cultivation was found seven thousand years ago [11]. The interest about this crop is increasing over the world, both due to abiotic stress tolerance and superior nutritional benefits [44]. Grain of quinoa is gluten-free, contain substantial amount of all essentialamino acid, vitamins, (A, B2 and E), minerals (Ca, K, Fe, Mn) and health supportive fatty-acids (omega 3) [13]. Recently in Pakistan quinoa has been successfully introduced, cultivated and basic production technology developed [45]. This traditional Andean seed crop has been cultivated in the Peruvian and Bolivian Andes [46] and the crop is rapidly gaining interest throughout the world [24]. Quinoa is well adapted to grow under unfavorable soil and climatic conditions [19]. Quinoa is a halophytic species emerging as a potential new crop in many regions of the world because of the nutritional composition of their seeds [13,24,47]. It has all the essential amino acids for human life and in quantities close to the necessary equilibrium [48].

Its balanced composition makes the protein quality of quinoa comparable to that of mother milk [49,50]. Despite the high nutritional value of the seeds, they also contain in the pericarp the anti-nutritious component, saponin, in a certain concentration depending mainly on the variety (Ward, 2000) and on the stress conditions of the plant [51]. Protein content in most quinoa accessions has been reported to range from 12 to 17%, depending on variety, environment, and inputs [52]. This range tends to be higher than the protein content of wheat, barley, and rice, which were reported to be 10.5–14%, 8–14%, and 6–7%, respectively [53,54]. Additionally, quinoa has a well-balanced complement of essential amino acids. Specifically, quinoa is rich in lysine, which is considered the first limiting essential amino acid in cereals [55]. Furthermore, with a lack of gluten protein, quinoa can be safely consumed by gluten sensitive/intolerant population [56]. The aim of the study was to evaluate the salt tolerance potential of newly introduced quiona (Chenopodium quinoa Willd), against combined salinity and sodicity stresses.

Materials and Methods

A pot study was conducted to evaluate the growth and yield of (Chenopodium quinoa Willd.) under different artificial developed saline- sodic soils at green house of Land Resources Research Institute, National Agricultural Research Centre, Islamabad, Pakistan during, 27th November 2017 to April 2018. The soil used for the pot experiment was analysed and having 7.99 pHs, 1.32 ECe (dSm-1), 3.88 SAR (mmol L-1)1/2, 29.01 Saturation Percentage (%), 0.42 O.M. (%), 7.89 Available P (mg Kg-1) and 106.32 Extractable K (mg Kg-1). Considering the pre- sowing soil analysis, the ECe (Electrical conductivity) and SAR (Sodium Absorption Ratio) was artificially developed with salts of NaCl, Na2 SO4, CaCl2 and MgSO4 using Quadratic Equation.10 Kg soil was used to fill each pot. 10 seeds of Conocarpus erectus were sown in each pot. Fertilizer was applied @75-60-50 NPK Kg ha-1NPK Kg ha-1. Treatments were as T1=<3.66(dSm-1)+<13.85(mmolL-1)1/2, T2= 5(dSm-1)+25(mmol L-1)1/2, T3=10(dSm-1)+25(mmolL-1)1/2, T4=15(dSm-1)+25(mmol L-1)1/2, T5= 20(dSm-1)+25 (mmolL-1)1/2, T6=25(dSm-1)+25(mmolL-1)1/2, T7=5(dSm-1)+ 30(mmol L-1)1/2, T8=10(dSm-1)+30 (mmol L-1)1/2, T9= 15(dSm-1)+30(mmol L-1)1/2, T10=20(dSm-1)+30(mmol L-1)1/2, T11=25(dSm-1)+30(mmol L-1)1/2, T12= 5(dSm-1)+40(mmol L-1)1/2, T13=10(dSm-1)+40(mmol L-1)1/2, T14= 15(dSm-1)+40(mmol L-1)1/2, T15=20 (dSm-1)+40 (mmol L-1)1/2 and T16= 25 (dSm-1) + 40(mmol L-1)1/2. Completely randomized deign was applied with three repeats. Data on biomass and grain yield were collected. The data obtained were subjected to statistical analysis using the STATISTIX statistical software (Version 8.1) and the mean values were compared using least significant difference (LSD) (Steel and Torrie, 1997).

Table 1: Effect of salinity/sodicity on growth and yield per pot of Quiona.

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T1=<3.66(dSm-1)+<13.85(mmol L-1)1/2, T2=5(dSm-1)+25(mmol L-1)1/2, T3=10(dSm-1)+25(mmol L-1)1/2, T4=15(dSm-1)+25(mmol L-1)1/2, T5=20(dSm-1)+25(mmol L-1)1/2, T6=25(dSm-1)+25(mmol L-1)1/2, T7=5(dSm-1)+30(mmol L-1)1/2, T8=10(dSm-1)+30(mmol L-1)1/2, T9=15(dSm- 1)+30(mmol L-1)1/2, T10=20(dSm-1)+30(mmol L-1)1/2, T11=25(dSm-1)+30(mmol L-1)1/2, T12=5(dSm-1)+40(mmol L-1)1/2, T13=10(dSm- 1)+40(mmol L-1)1/2, T14=15(dSm-1)+40(mmol L-1)1/2, T15=20(dSm-1)+40(mmol L-1)1/2 and T16=25(dSm-1)+40(mmol L-1)1/2.

This variation indicated the severe impact of salinity and sodicity in growth of quiona plant. The conditions for crop growth are very difficult in the high region of the Andes, where the most harmful a biotic adverse factor that affect crop production are drought, frost, soil salinity, hail, snow, wind, flooding, and heat [19]. Quinoa can be successfully grown on marginal soils [11] which were the main objective to introduce in Pakistan has yet to be tested under local salt -affected conditions. Significant variations exist among quinoa accessions for physiological and agronomical variables when raised under different set of saline conditions [58]. Data regarding grain yield performed significant differences as indicated in Table 1. The worst impact of saline and sodic soil stresses showed the lowest result (26.4g) in T16, However, T1 i.e. control gained the highest grain yield (98g). This reduction in grain yield was addressed by the toxic effects of salts in saline sodic soils. 4.90 % decrease over control in grain yield by T2 while T16 produced the increased % decrease over control in grain yield (73.06). Similar trend was also observed in straw yield as presented in Table 1. The salinity issue leads producers to grow more salt-tolerant crops, such as quinoa Many studies have focused on quinoa’ salt tolerance to soil salinity, with a particular emphasis on plant physiology [10,58-65] and agronomic characteristics such as germination rate, plant height, and yield [66-75].


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