Evaluation of Agronomic Performance and Seed Oil Composition of 15 Sunflower Genotypes in South Madagascar

Sunflower (Helianthus annuus L.) is one of the world’s most important oilseed crops together with oil palm (Elaeis guineensis Jacq.), soybean (Glycine max (L.) Merr.) and rapeseed (Brassica napus L.). Despite the 8.5% of world sunflower cultivation is found in Africa, just few studies on oil seed performances and their chemical composition were carried out in tropical countries, thus reducing the knowledge on the adaptability and performances of this crop in humid areas. In this study the agronomic performance, environmental adaptability, oilseed production and fatty acid composition of 15 sunflower varieties cultivated in two underexploited areas of the Plateau de l’Horombe in southern Madagascar were evaluated. Results of this study indicated that: 1) sunflower has well performed in sub-arid localities thanks to its adaptability to harsh conditions, with similar performances to those obtained in other worldwide countries;2) the well-structured and fertile soil resulted to be the key driver of sunflower performances;3) the most productive hybrids between the sites were PR63D82 (conventional typology) and Klarika for yield and oil content, respectively;4) the oleic/linoleic ratio of both HO and conventional sunflowers was influenced by changes in temperature.

Predicted and measured soil retention curve parameters in Lombardy region north of Italy

Water retention characteristics are fundamental input parameters in any modeling study on water flow and solute transport.These properties are difficult to measure and for that reason,we usually need to use direct and indirect methods to determine them.An extensive comparison between measured and estimated results is needed to determine their applicability for a range of different soils.However this study attempts to make a contribution specifically in this connection.These properties were determined in two representative sites located in Landriano field,in Lombardy region,northern Italy.In the laboratory we used the pressure plate apparatus and the tensiometric box.Field soil water retention was determined including measurements of soil water content with SENTEK probes and matric potential with tensiometers.The soil waer retention curves(SWRC)were also settled on with some recently developed pedo-transfert functions(PTFs).Field retention curves were compared against those obtained from PTFs estimations and laboratory measurements.The comparison showed that laboratory measurements were the most accurate.They had the highest ranking for the validation indices(RMSE ranging between 2.4%and 7.7%and bias between 0.1%and 6.4%).The second best technique was the PTF Rosetta(Schaap et al.2001).They perform only slightly poorer than the laboratory measurements(RMSE ranging between 2.7%and 10%and bias between 0.3%and 7.7%).The lowest prediction accuracy is observed for the Rawls and Brakensiek(1985)PTF(RMSE ranging between 6.3%and 17%and bias between 5%and 10%)which is in contradiction with previous finding(Calzolari et al.,2001),showing that this function is well representing the retention characteristics of the area.Due to time and cost investments of laboratory and field measurements,we conclude that the Rosetta PTF developed by Schaap et al.(2001)appears to be the best to predict the soil moisture retention curve from easily available soil properties in the Lombardy area and further field investigations would be useful to support this finding.

Quantifying water stress effect on daily light use efficiency in Mediterranean ecosystems using satellite data

The capacity of six water stress factors(ε′(i))to track daily light use efficiency(ε)of water-limited ecosystems was evaluated.These factors are computed with remote sensing operational products and a limited amount of ground data:ε′1 uses ground precipitation and air temperature,and satellite incoming global solar radiation;ε′(2) uses ground air temperature,and satellite actual evapotranspiration and incoming global solar radiation;ε′_(3) uses satellite actual and potential evapotranspiration;ε′_(4) uses satellite soil moisture;ε′_(5) uses satellite-derived photochemical reflectance index;and ε′_(6) uses ground vapor pressure deficit.These factors were implemented in a production efficiency model based on Monteith’s approach in order to assess their performance for modeling gross primary production(GPP).Estimated GPP was compared to reference GPP from eddy covariance(EC)measurements(GPP EC)in three sites placed in the Iberian Peninsula(two open shrublands and one savanna).ε′_(i) were correlated to ε,which was calculated by dividing GPP EC by ground measured photosynthetically active radiation(PAR)and satellite-derived fraction of absorbed PAR.Best results were achieved by ε′(1),ε′(2),ε′(3) and ε′(4) explaining around 40% and 50% of ε variance in open shurblands and savanna,respectively.In terms of GPP,R^(2)≈0.70 were obtained in these cases.