Irrigation of Sunflower

Sunflower is grown in many parts of the world as a rain-fed, dryland, or irrigated crop. The plant’s deep root system is responsible for providing drought tolerance, as it can absorb water at a depth of 1,5 meters from the soil surface. With an extensive (up to 2 m = 6 feet) and heavily branched root system, sunflower can extract water and nutrients from deeper soil layers that most other annual crops cannot reach. When there is plenty of water available in the environment-soil, the plant can use 50.8-76.2mm more water during the growing season than wheat but less than corn and soybean (1).

Throughout the growing season, the sunflower needs approximately 500-670 mm of water (7.1 mm per day) (Yawson et al., 2011, 1). As a dryland crop, sunflower depends on the soil stored water and the rainfalls to satisfy these needs. However, even if the total amount of water is covered by rainfalls, the irregularity of the water supply during different plant growth stages can cause drought stress and, as a result, yield loss. The yield gain was outstanding when the crop was grown under irrigation. More specifically, irrigated oil-type sunflower hybrids produced on average 92 kg seeds per hectare more than the dryland (1). Scientists’ and farmers’ experiments confirm this positive impact of irrigation in sunflowers with a 100 to 200% yield increase under irrigation (2). This expected increase can be calculated more easily by considering the following principle. Sunflower can extract up to 190 mm of water stored in 1.8 m (6 feet) soil depth. For every 25 mm of water used above that plant capacity, the yield increases on average by 168.13 kg per hectare (150 lb/acre) (3).

Growth stages and water requirements of sunflower

The crop requirements concerning the moment and amount of irrigation depend on the variety, the plant population, the environmental conditions, and the soil profile. As mentioned before, it is vital to supply the plants with sufficient water when they need it most. In general, rainfall or irrigation is needed every 14 days to keep soil moisture at a desirable level and maximize crop yield. The average daily water use increases as the plant grows. More specifically, until plant emergence, it is around 0.5-0.7 mm per day, reaching 6-8 mm per day from head development and flowering until grain filling. These numbers may vary depending on the temperature.

The most critical period to avoid water stress is between flowering and achene filling. Water scarcity during these stages can decrease the yield and quality of the seed oil (Hussain et al., 2018). Depending on the region, zero to six irrigation sessions may be needed. There are generally two to three cost-effective applications that can balance the yield gain and watering expenses and cover the plant’s needs at the critical stages of bud initiation, flower opening, and seed filling. As a result, the first one should ensure adequate moisture at planting to facilitate crop establishment and encourage root development. The farmer may need to apply the second irrigation session when the sunflower bud reaches about 1.9-2.5 cm (0.75-1 in) in diameter (R5.9 reproductive stages). Lack of sufficient water during this phase can cause up to 50% yield reduction. If the temperature is high and no rains occur, 1-2 more applications may be needed, one 20 days after the previous and one in late grain fill (4, 2). Finally, the plants may succeed in optimum water utilization and maximum yields if their nutritional needs (N, P, K) are also sufficiently covered.

Irrigation Methods used in sunflower

Unfortunately, many farmers misinterpret the benefits of irrigating sunflowers and use excessive water amounts choosing furrow or basin irrigation (Ebrahimian et al., 2019). However, such applications have been linked with increased plant lodging risk. Sunflower lodging may be further categorized as root lodging and stem lodging. Root lodging is more common in the case of a water surplus in the soil because of the heavy top weight of the head and the lack of support due to softened soil in the root zone (Sposaro et al., 2010). Other systems like drip irrigation or irrigation with sprinklers limit this risk (Zou et al., 2020). A common option is using a multiple-meter hose reel irrigation boom. Sophisticated drip irrigation in sunflower farming has also been found to substantially increase plant height, stem diameter, head diameter, leaves weight per plant, head weight per plant, seeds weight per head, seed yield and oil yield (5). 

References

1. https://www.ag.ndsu.edu/publications/crops/sunflower-production-guide#section-1
2. https://www.ndsu.edu/agriculture/ag-hub/ag-topics/crop-production/crops/sunflowers/irrigated-sunflowers
3. https://www.ars.usda.gov/ARSUserFiles/30100000/1990-1999documents/342%201998%20Nielsen%20FS.pdf
4. https://sanangelo.tamu.edu/extension/agronomy/agronomy-publications/sunflower-production-guide/
5. https://www.academia.edu/19712095/Growth_productivity_and_water_use_of_sunflower_crop_under_drip_irrigation_system

Ebrahimian, E., Seyyedi, S.M., Bybordi, A., Damalas, C.A., 2019. Seed yield and oil quality of sunflower, safflower, and sesame under different levels of irrigation water availability. Agric. Water Manage. 218, 149–157.

Zou, H., Fan, J., Zhang, F., Xiang, Y., Wu, L., Yan, S., 2020. Optimization of drip irrigation and fertilization regimes for high grain yield, crop water productivity and economic benefits of spring maize of Northwest China. Agric. Water Manage 230, 105986. 

Sposaro, M.M., Berry, P.M., Sterling, M., Hall, A.J., Chimenti, C.A., 2010. Modelling root and stem lodging in sunflower. Field Crops Res. 119, 125–134. 

Yawson, D. O., Bonsu, M., Armah, F. A., & Afrifa, E. K. (2011). Water requirement of sunflower (Helianthus annuus L.) in a tropical humid-coastal savanna zone.

Hussain, M., Farooq, S., Hasan, W., Ul-Allah, S., Tanveer, M., Farooq, M., & Nawaz, A. (2018). Drought stress in sunflower: Physiological effects and its management through breeding and agronomic alternatives. Agricultural Water Management, 201, 152-166. doi: 10.1016/j.agwat.2018.01.028

Sunflower: History, Uses and Plant information

Sunflower Variety Selection

Sunflower Soil preparation, Soil requirements and Seeding requirements

Irrigation of sunflower

Sunflower Fertilizer Requirements

Weed Management in Sunflower Farming

Sunflower pests and diseases

Yield, harvest, storage of sunflower