Impact of Irrigation Deficit on Yield, and Water Productivity of Quinoa

INTRODUCTION

The quinoa plant belongs to the genus Chenopodium and the family Chenopodiaceae.(Iqbal, 2015). It is well adapted to arid and semi-arid regions. It can be planted on high land up to 4000 m above sea level. Quinoa is a C3 annual dicot of 0.5 to 2 m height, terminating in a panicle consisting of small flowers, and with only one seed of around 2 mm produced per flower. (Geerts and Garcia, 2012). Quinoa seed has an excellent balance of carbohydrates, lipids, and protein for nutrition (Maradini-Filho et al., 2017). Quinoa protein has all essential amino acids found in wheat. ln addition to lysine and sulfur amino acids (Escuredo et al., 2014). Besides, it contains a considerable amount of fiber and minerals, such as calcium and iron (Ando et al., 2002). Grains of quinoa is used instead of wheat grains in bread and other bakeries production (Abou-Zaid et al., 2012 and Koehler et al., 2014).Quinoa plants are resistant to various stresses such as salinity, cold air, high solar radiation, low temperature, and can be planted in different soil types with the broad range of pH values (Jacobsen et al., 1998). Drought stress reduces plant growth in terms of shoot and root fresh as well as dry weights along with chlorophyll a and b contents and relative water contents (RWC) while a considerable increase was observed in hydrogen peroxide (H₂O₂), malondialdehyde (MDA), proline and total sugar contents in some quinoa cultivars (Naz et al., 2020). Under water-scarce conditions, tolerance of plants is highly associated with accumulation of proline, which is an amino acid (non-protein), produces in leaf tissues (Ashraf and Foolad, 2007). Jensen et al. (2000) observed yield reduction when water stress was applied during the flowering stage and grain filling stage, while application of water stress during the vegetative stage led to increased yield. Drought in early vegetative stages may prolong its life cycle, allowing the plant to make up for growth lost during the early drought if water is available later. The plant also avoids the negative effects of drought through fast and deep rooting, particularly in dry soils. Quinoa also reduces its leaf area by controlled leaf senescence under drought. The Food and Agriculture Organization of the United Nations (FAO) has identified Quinoa as an important alternative crop to contribute to future global food security and declared the year 2013 as the international year of quinoa (FAO, 2012). Therefore, the present research was conducted to investigate the impact of different irrigation deficits on Quinoa production as compared with rain-fed irrigation.

MATERIALS AND METHODS:

1.The site of the experiment:

The present investigation was carried out at the experimental farm of the City of Scientific Research and Technological Applications SRTA-City, Old Borg El-Arab, Alexandria Governorate, Egypt. Geographically, the experimental farm is located at 30° 53’N and 29° 32’E, with an elevation of about 28 meters above sea level.

2. Climatic conditions:

The climatic conditions were extracted from NASA web-meteorological free data (power.larc.nasa.gov) and the new Borg El-Arab station. The values of climatic parameters during the growing season (2018 – 2019)  i.e. temperature (T °C), relative humidity (RH %), rainfall (Pe mm), wind speed (U2 m/s at 2m height), and atmospheric pressure (P kPa) are presented in Table (1).

Table (1). Climatological data for the experimental site during the growing season

3. Field experiment:

3.1. Planting The field experiment was planted with a Quinoa crop. Quinoa (chenopodium quinoa Willd) variety Chipaya. The sowing date was Nov. 11, 2018, and the harvesting at Mar.17, 2019. The growing season was 126 days. The soil type was sandy clay loam and some soil physical and chemical properties are illustrated in Table (2). The seeds were sowed in a soil bed with 0.5 m width and 10.5 m length with 0.2 m between plants(2 seeds per hole) . The number of  plants per m² was 20 plants.

 3.2. Irrigation

The drip irrigation system was constructed as 0.5 m between rows and 10.5 m in length. The irrigation practice was done weekly using a drip irrigation system with a capacity of 6.0 L/hr.

3.3. Fertilization

The experiment was fertilized with recommended doses of ammonium nitrate (33.5% N) as 100 kg/fed, superphosphate (15.5% P₂O₅) as 50 kg/fed and potassium sulfate (48% K₂O) as 50 kg/fed.

3.4. Experimental treatments

The experiment was designed to investigate the effect of irrigation regimes as 40, 60, 80, and 100% of the reference evapotranspiration (ET0) as compared with rainfed irrigation. The experimental design was a Randomized Complete Block Design with three replicates.

 4. Soil analysis

The soil samples were collected from the experimental site at two depths; surface 0 – 30 cm and subsurface 30-60 cm before planting to determine the soil's physical and chemical properties. Soil samples were air-dried and sieved through a 2-mm sieve and analyzed according to the methods described by Carter and Gregorich (2008) and presented in Table (2).

4.1. Physical properties of soil

Particle-size distribution is determined by the hydrometer method according to Carter and Gregorich (2008).

4.2. Chemical properties of soil

Soil Electrical conductivity (EC) (1:1 w/v) was measured using a conductivity meter according to Jackson (1973). Organic carbon OC, Organic Matter OM %, CaCO3 %, cations and anions, CEC meq/100 gm soil and available macronutrients NPK (ppm) were laboratory determined according to Jackson (1973), Richards (1972) and Carter and Gregorich (2008).

5. Water analysis:

The following parameters of irrigation water were determined; pH, Electrical conductivity (EC), soluble cations (Na, K, Ca, and Mg), and soluble anions (CO₃, HCO₃, Cl, and SO₄) in Table (3).

Table (2). Some soil physical and chemical properties

Table (3). Chemical properties of the irrigation water

6. Plant chracteristics

At harvest time (126 days after sowing), the following parameters were recorded:

6.1. yield and seed characteristics: foliage yield (ton/fed), total yield (ton/fed), seed weight (g/plant), seed weight (g/m²), weight of 1000 seeds, seed yield (ton/fed), harvest index(%), and seed water content(%).

6.2. water characteristics Qiunoa water requriments(m³/fed), and irrigation water use efficiency (water productivity), kg/m³.

7. Statistical analysis 

All obtained data of the present study were, statistically, analyzed according to the design used by the Statistix (2019) computer software program and were tested by analysis of variance. The revised least significant difference test at 0.05 level of probability was used to compare the differences among the means of the various treatment combinations as illustrated by Duncan (1955) and Gomez and Gomez (1984).

RESULTS AND DISCUSSION

1. Quinoa yield and seed characteristic

The irrigation regime treatments had a highly significant effect on foliage and total yield (Table 4). The highest values were attained at 100% of the ET_o irrigation regime. It  accounted for 2.82 and 2.72 times increase over the rainfed irrigation treatment, respectively. Seed weight per plant and seed weight per m² reached a maximum value at 100% of ET₀. It increased by about 216.70 and 216.68% over the rainfed irrigation regime, respectively. There were no significant differences between 100 and 80 % of ET₀ treatments. Seed weight per plant was 10.185 and 8.781 g/plant at 100 and 80% of ET_0,respectively; as well, seed weight per m² was 203.69 and 175.62 g/m² at 100 and 80 % of ET_0, respectively. The weight of 1000-seeds reached the highest value at 60% of the ET₀ irrigation regime (3.43 g). It increased by 18.28 % over the rainfed irrigation regime. Seed yield per fed recorded the highest value at 100% of the ET₀ irrigation regime (0.616 ton/fed). The increase over the rainfed irrigation treatment was 155.56%. There were no significant differences between irrigation at 100 and 60% of the ET₀ irrigation regime as shown in Table 4 and Figure 1. The harvest index reached the highest value at 40% of ET₀ irrigation treatment (45.81%). It increased by about 39.96% over the rainfed irrigation regime (32.73%). In addition, the seed water content reached its maximum value at 100% of ET₀treatment and decreased with other irrigation regimes (Table 4).

Table (4). Quinoa seed yield and seed quality as affected by irrigation regime

Figure (1): Effect of irrigation deficit on seed yield of quinoa

. Quinoa water requirements and water productivity

The water use efficiency calculated as:

The total applied water (TAW) were 931.4, 796.6, 658.0, 523.3, and 285.6 m³/fed for irrigation treatments of 100, 80, 60, and 40% of ET₀ and rainfed irrigation, respectively (Table 5). The calculated crop evapotranspiration reached  229.0, 183.2, 137.4, 91.6, and 50.2 mm/season, respectively. The irrigation water-use efficiency (IWUE) or water productivity (WP) as kg seeds/m³ of applied water reached the values of 0.681, 0.655, 0.806, 0.778, and 0.712 kg/m³ for 100, 80, 60, 40% of ET_0, and rainfed treatments, respectively. The maximum value was obtanid for 60% of ET₀ (Table 5 and Figure 2). The consumptive water-use efficiency (CWUE) reached its maximum value at 40% of the ET₀ irrigation regime. Its values were 2.769, 2.847, 3.858, 4.443, and 4.053 kg/mm of applied water, respectively. Irrigation at 60% of ET₀was the best treatment resulting in the highst water productivity (IWUE). It increased by about 13.20% over the rainfed irrigation treatment. At this treatment, it is possible to save about 273.4m³/fed of applied water; which accounted for 29.35% of water-saving.

Table (5). Quinoa water requirements of Quinoa as affected by irrigation regime

TAW: Total applied water             CWUE: Consuming water use efficiency

IWUE: Irrigation water use efficiency          ETc: crop evapotranspiration

Figure (2). Effect of irrigation deficit on water productivity of  quinoa