FORTH/ICE-HT

Identification of most promising strategies to increase oil and biomass yield of sunflower in European Union

F. Flénet, A. Quinsac 24 April 2009, Foggia

FORTH/ICE-HT

Introduction

• Sunflower is the

second most important oilseed crop

UE, but the area has decreased in • Sunflower is mainly cultivated in

Southern Europe

: Romania (900 000 ha in 2007), Spain (613 000 ha), Bulgaria (540 000 ha), France (537 000 ha), Hungary (470 000 ha) and Italy (130 000 ha) • The strategies

to increase seed yield

were investigated : – 1) To increase the seed yield potential – 2) To decrease the effect of water stress, 3) diseases and 4) other limiting factors • Little information was available about oil content, and very little information about optimizing biomass yield • In this presentation, the main strategies are discussed

FORTH/ICE-HT

Strategy 1 : to increase the potential seed yield

(1)

• Potential seed yield increased by 40 % from 1970 to 2000, due to : – An increase in harvest index

Varieties

Mirasol Primasol Albena Vidoc Santiago Prodisol Melody LG5660 Heliasol

Year of official registration

1978 1979 1988 1989 1993 1995 1996 1998 2000

125 120 115 110 105 100 95 90 85 80 75 1975 Montpellier (2001 - 2002) Toulouse (2002) 1980 1985 1990 1995 2000 2005 Year of offical registration of the variety

(Results from Debaeke et al., 2004)

– A greater efficiency to intercept solar radiation per unit of leaf area • No obvious increase in seed oil content was observed

FORTH/ICE-HT

Strategy 1 : to increase the potential seed yield

(2)

• Further improvements in seed yield potential are possible – The main physiological processes explaining seed yield potential are, in order of importance : • biomass allocation • light interception through the canopy architecture; • phenology – No cultivars optimize all the physiological processes, hence

improvements are still possible

– Quantitative genetic methods such as QTL can be used to evaluate the variability of these physiological processes, and to

increase the efficiency of breeding programs

FORTH/ICE-HT

Strategy 2 : to decrease the effect of water stress

(1)

• Water stress is a major limiting factor –

Under water stress, sunflower is able to produce greater seed yields than most other crops



sunflower is mainly cultivated without irrigation

(96 % of the area in France…), or with a limited amount of irrigated water 

plant available water is the most limiting factor

of dryland agriculture in semiarid regions

FORTH/ICE-HT

Strategy 2 : to decrease the effect of water stress

(2)

• Strategies to decrease the effect of water stress –

To increase the drought tolerance of varieties

Crop models can be useful to test varieties and to identify the best physiological characteristics

–

To better adapt crop management to water availability

To optimize the choice of variety, date of sowing, planting density and N fertilizer, depending on climate and soil water holding capacity

–

To increase the irrigation of sunflower

If less water is available for agriculture, this crop with a low water requirement could replace current irrigated crops

–

To convince farmers to follow recommendations, because better cultural practices would improve yields

For instance, in South-West of France there is a tendency to reduce the cost of inputs, resulting in plant population densities below the recommendations in half of the area…

FORTH/ICE-HT

Strategy 3 : to decrease the effect of diseases

(1)

• Some diseases are major limiting factors

Main diseases

Downy mildew Broomrape White rot Phomopsis stem canker Alternaria blight Phoma black stem

Main countries affected

All countries in EU Bulgaria, Romania, Spain Bulgaria, France, Hungary, Romania Romania, Hungary, France All countries in EU France 100 %.

Effects of the disease

If entire areas are affected, the decrease in yield ranges from 50 % (late development) to 100 % (early development) in the infected areas In case of severe infections, losses can reach up to 50 % and near Almost 100 % of yield losses if infection occurs near anthesis, but on a regional basis losses are generally from 1 to 5 % The disease occurrence has lessened in the past years Infestations can cause defoliation and yield losses as high as 60 to 80 %.

At a regional scale, in France yield losses range from 0.2 to 0.5 t/ha

FORTH/ICE-HT

Strategy 3 : to decrease the effect of diseases

(2)

• Strategies to decrease the effect of diseases

Main diseases Strategies to control the diseases

Downy mildew Genetic and chemical control, but adaptations of the pathogen give continuous challenge to scientists Broomrape White rot Genetic resistance, but it is rapidly overcome by evolutions of the parasite.

To use CLEARFIELD sunflowers (resistant to imidazolinone herbicide family) and the application of imidazolinone herbicide to control broomrape To avoid dissemination by machinery movement along the different growing areas The most effective control is an integrated program of cultural practices (no excessive N fertilization, wide row spacing…), spatial isolation, genetic resistance and chemicals Phomopsis stem canker Alternaria blight Genetic resistance has been very efficient, because it is polygenic (difficult to overcome) Chemical application Cultural practices (density < 50 000 plants/ha, N < 60 kg/ha and deep incorporation of stalks) and spatial isolation Resistance breeding Phoma black stem Susceptibility of cultivars (there is a need to study the tolerance of hybrids) One fungicide is effective, but it is not available for farmers (homologation is needed) Cultural practices (limited N fertilization and irrigation help to control the disease)

FORTH/ICE-HT

Strategy 4 : to decrease the effect of other factors

• The main other limiting factors – Some weeds are not controlled by pre-plant or pre-emergence herbicides The recent introduction of herbicide-tolerant sunflowers (CLEARFIELD and EXPRESS) makes possible a post-emergent weed control option – Insect damages are mainly a problem in eastern Europe (Bulgaria, Hungary and Romania) The use of chemical insecticides is a primary tool, but alternative pest management strategies are possible (rotating crops, altering planting dates, increasing natural ennemies, sex pheromones…) – Slugs, birds and game animals : in France, the yield loss (0.3 to 0.4 t/ha in some areas) is greater than that attributed to insects The strategy should focus on seed treatments and sowing practices to obtain a better seedling emergence, while a better understanding of the biology of animals would be helpful

FORTH/ICE-HT

Conclusion

• A global strategy is needed to increase seed yield

– The best combination of decisions must be taken in order to obtain high yields, at low costs and with little impact on environment :

Decisions to be taken are : the distribution of crops in the landscape, machinery movements along the growing areas, crop rotation, the choice of variety, cultural practices and chemical applications The risks of drought, diseases and other limiting factors must be taken into account

– Studies are needed to design and to test these combinations of decisions, but the conformation of farmers to adopt the recommended practices is also a challenge – Breeding will help to obtain better results (increased yield, lower costs and lower impacts on environment)

Breeding should focus on seed yield potential, but also on drought tolerance, and on resistance to diseases and insects