It is tolerant of both low and high temperatures, however, more tolerant to low temperatures. The crop is particularly sensitive to high soil temperature during emergence. In South Africa, this problem is aggravated in the sandy soils of the Western Free State and North West, resulting in a poor or erratic plant stand. Sunflower seeds will germinate at 21 degree Centigrade, however, temperatures of at least 14 to 21 degree Centigrade are required for satisfactory germination. Seeds are not affected by vernalisation (cold) in the early germination stages. At later stages freezing temperatures could damage the crop. Temperatures lower than the freezing levels are required before maturing sunflower plants would die off. The optimum temperature for growth is 23 to 28 degree Centigrade , however, a wider range of temperatures up to 34 degree Centigrade show little effect on productivity. Extremely high temperatures have been shown to lower oil percentage, reduce seed fill and germination.
The rainfall requirement ranges from 500 to 1 000 mm. Sunflower is an inefficient user of water, as measured by the volume of water transpired per gramme of plant above-ground dry matter. It is a crop which, compared to other crops, performs well under drought conditions; this is probably the main reason for the crop's popularity in the marginal areas of South Africa. However, the crop is not considered highly drought tolerant, but often produces satisfactory results while other crops are damaged during drought. Its extensively branched taproot, penetrating to 2 m, enables the plant to survive times of water stress. A critical time for water stress is the period 20 days before and 20 days after flowering. If stress is likely during this period, irrigation will increase yield, oil percentage and test weight. Protein percentage, however, will decrease.
Sunflower will grow in a wide range of fertile soil types; sandy loam to clays with pH value ranging from 6,0 to 7,5. Traditionally, sunflower cultivation has been limited to soils where the clay percentage varies between 15 and 55 % (in other words, sandy loam to clay soil types). At present the major planting areas are in soils with a clay percentage of less than 20. Sunflower has a low salt tolerance, however, it is somewhat better than field bean or soya-bean in this respect. Good soil drainage is required for sunflower production, but this crop does not differ substantially from other field crops in flooding tolerance. Soils with good water-holding capacity (clays) will be preferred under dryland conditions.
Many different tillage systems can be used effectively for sunflower production. Soil preparation should be focused on decreasing runoff, especially in the case of soils with a low infiltration rate. These losses can be limited to a great extent by applying the correct soil cultivation practices. Conventional systems of seedbed preparation consist of mouldboard plowing or chisel plowing. The aim of the cultivation is to break up limiting layers, destroy weeds, provide a suitable seedbed and to break the soil surface and at 6 the same time to ensure maximum rainfall infiltration, as well as to prevent wind and water erosion. Both germination percentage and lodging have been shown to increase in ridge-till systems vs. level plantings. Several tillage systems have been used with some success in specific environments. Major considerations are:
The planting density for sunflower ranges from 25 000 to 35 000 plants per hectare, depending on the yield potential of the area. Row width has little influence on grain yield. It can range from 90 to -100 cm, however, wider rows such as 1,5 m to 2,1 m can also be used, particularly to accommodate other farm implements. The required spacing in the row is about 30 cm. In South Africa, sunflower is planted from the beginning of November to the end of December in the eastern areas and to mid-January in the western areas. Sunflower seeds are planted at relatively shallow depths. In soil with a high clay content, seeds are planted at a depth of 25 mm. In sandy soils, seeds can be planted at a depth of up to 50 mm.
Compared to grain crops, sunflower utilises soil nutrients exceptionally well. The main reason for this is the finely branched and extensive root system. The roots come into contact with nutrients which cannot be utilised by other crops.
Sunflower normally reacts well to nitrogen and phosphorus fertilisation, where there is a shortage of these elements in the soil. It is therefore essential that any fertilisation programme for sunflower should be based on soil analyses. Soil analyses will not only lead to more appropriate fertilisation levels, but can also significantly limit unnecessary fertilisation costs.
When there is a shortage, the growth rate decreases dramatically, leaves turn to pale green and the lower leaves die-off.
A shortage of phosphorus is characterised by retarded growth. In serious cases necrosis can be detected on the tips of the lower leaves. Factors which should be taken into account when planning a phosphorus fertilisation programme, are the following:
Although sunflower draws large quantities of potassium from the soil, potassium fertilisation is usually unnecessary, as South African soils generally have adequate quantities of this nutrient.
Shortages of boron and molybdenum often limit the growth and yield of sunflower in the eastern parts of the country. To avoid problems concerning these two elements, care should be taken to apply fertiliser containing boron and to ensure that seeds are treated with molybdenum prior to planting. Local seed companies usually treat their seed with molybdenum. If no soil analysis is available, 50 to 100 kg/ha of a 3:2:1 (25) fertiliser mixture applied at planting is adequate for a yield potential of 1 000 to 1 500 kg/ha.
In most cases South African sunflower is cultivated under dry land during the summer rainfall season (November to March). In areas with low rainfall, water supply can be supplemented with irrigation in order to increase yield. The method of irrigation will depend on the water availability and the available irrigation equipments. The pH of the irrigation water should be slightly neutral.
Efficient weed control is a prerequisite for high sunflower yields. It is achieved by a combination of mechanical and chemical practices. Young 9 plants are highly sensitive to strong weed competition and cannot develop fast enough to form a full shade covering which can suppress weed seedlings. Therefore, the first 6 weeks after planting are a critical period for the crop. Yields can be increased significantly by keeping fields free of weeds during this time.
Mechanical weed control can be very effective, provided it is done in time and with care not to damage the crop. Chemical weed control can be applied successfully together with mechanical methods and cultivation practices to bring about better weed control. The following tips are given for mechanical control:
The use of herbicides has many advantages, of which the most important is that effective weed control can be applied during wet periods when mechanical weed control is impossible. If sunflower is cultivated in crop rotation with maize, weeds can be controlled more effectively in both crops as grass and broadleaf herbicides can be used in continuous succession.
Insect pests have become major potential yield-reducing factors in sunflower producing areas.
Sunflower should be grown in rotation with other crops as:
Harvesting should commence as soon as 80 % of the sunflower heads are brown in order to minimise losses caused by birds, lodging and shattering. The leaves turn yellowish during harvesting maturity. Sunflower is generally mature long before it is dry enough for combining. The sunflower plant is physiologically mature when the back of the head has turned from green to yellow and the bracts are turning brown, about 30 to 45 days after bloom, and seed moisture is about 35 %. The total growing period (from seeding to harvesting) for sunflower ranges from 125 to 130 days.
Harvesting is done either manually or mechanically. Manual harvesting is practiced by cutting the crop with a sickle or knife. Commercially available sunflower headers are useful in decreasing loss of seed as the crop is direct combined. The combines are used to perform several operations such as cutting the crop, separating the grain from the straw, cleaning the grain from chaff and transporting grains to the storage tank. This equipment usually includes 20 to 90 cm width metal pans for catching matured seed and a three-armed or similar reel. A narrower (23 cm) pan width enables harvesting diagonal to the row, which produces smaller harvest losses in some situations. Harvesting with a combine harvester will save more time than manual harvesting.
Seeds should be below 12 % moisture for temporary storage and below 10 % for long-term storage. Seed up to 15 % moisture is satisfactory for temporary storage in freezing weather, however, spoilage is likely after a few days of warm weather. It is best to have on-farm storage available; however, storage in silos is the usual approach in South Africa. Aeration is essential, especially in the larger bins now available. Aeration may be accomplished with floor-mounted dusts or portable aerators. Sunflower should be rotated between bins when aeration is not available. An air space should be left in the top of the bin to facilitate checking the condition of stored seed. Sunflower can be stored more than one season under proper conditions (dry, clean, aerated, and in tight bins), however, processors of non-oilseed sunflower for human consumption prefer not to use seed that has been stored more than one season.
|Sunflower varieties and hybrids grown in India|
|Varieties||Developed By||Average yield||Characters|
|NSFH-36||Nuziveedu Seeds||8 to12||88-93days.8-12 q/acre in suitaible enviorment. 4-6 q/acre in unsuitable.175-190 cm. Oil content 42-44%. Suitable for rabi, kharif and summer seasons.|
|Chitra||JK Seeds, Hyderabad||8 - 10 q/acre||Duration 95-100 days in kharif and 100-105 days in rabi,Plant hight 165-170 cm. Oil content 38-40%|
|Surya||JK Seeds, Hyderabad||9-12 q/acre||Duration 90-95 days in kharif and 95-100 days in rabi,Plant hight 160-175 cm. Oil content 40-42%|
|JK 236||JK Seeds, Hyderabad||-||Duration 85-90 days, Oil content 42-44%|
|Market Year||Domestic Consumption (in 1000 MT)||Consumption Growth Rate||Production(in 1000 MT)||Production Growth Rate|
|1999||1300||8.33 %||1300||8.33 %|
|2000||1248||-4.00 %||1250||-3.85 %|
|2001||1449||16.11 %||1450||16.00 %|
|2002||1623||12.01 %||1625||12.07 %|
|2003||1698||4.62 %||1700||4.62 %|
|2004||1222||-28.03 %||1224||-28.00 %|
|2005||1547||26.60 %||1550||26.63 %|
|2006||1281||-17.19 %||1280||-17.42 %|
|2007||1116||-12.88 %||1120||-12.50 %|
|2008||995||-10.84 %||1000||-10.71 %|
|2009||816||-17.99 %||820||-18.00 %|
|2010||471||-42.28 %||425||-42.07 %|
|2011||466||-1.06 %||470||-1.05 %|
|2012||486||4.29 %||490||4.26 %|