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Ben-Gurion University of the Negev (2009)

Evapotranspiration, growth, yield and quality of pomegranate under combined drought and salinity stress

Bhantana Parashuram

Titre : Evapotranspiration, growth, yield and quality of pomegranate under combined drought and salinity stress

Auteur : Parashuram Bhantana

Université de soutenance : Ben-Gurion University of the Negev

Grade : Master of Science 2009

Résumé partiel
Plant growth, development and yield are limited by the nature’s wrath in the form of various biotic and abiotic stresses. Among abiotic stresses salinity and drought are prominent in limiting global food production. To cope with increasing food demand for the growing billions, incorporation of saline water and sustainable management of drought prone environments in agriculture are important. Thus the current study focused on evapotranspiration (ET), growth and yield of pomegranate (Punica granatum L.) in response to combined drought and salinity stress during 2008 and 2009. Experiments were conducted using eighty 0.2 m3 lysimeters with two varieties of pomegranate, ‘Wonderful’ and ‘SP-2’. The plants were grown with water having an electrical conductivity (ECiw) of 0.8, 1.2, 2.8, 5.0 and 8.5 dS m-1 and irrigated with 0.5, 0.75, 1.0 and 1.25 of the maximum lysimeter-measured ET (ETmax). ET data were recorded weekly based on the water balance method ; weekly measurements of the ECiw and drainage water electrical conductivity (ECdw) were done. Fruit yield was recorded during both years and the examination of various physical and chemical fruit parameters were performed. Daily ET was affected by salinity treatment, tree growth stages, and the climate during 2008 and 2009. Fluctuations of daily ET along the time were observed with the tree growth and climate, but the amplitude of fluctuation was higher in 2009 than 2008, which was due to increased tree growth. The highest and the lowest value of daily ET were recorded for the trees grown under ECiw of 0.8 and 8.5 dS m-1 respectively in both years. In the year 2008, ‘Wonderful’ and ‘SP-2’ varieties showed similar result in terms of daily ET. Thus measurement of daily ET was focused only for ‘Wonderful’ in the year 2009. Likewise, similar results were recorded for the cumulative ET (ETcum) both during the year 2008 and 2009. The ETcum was more than 3-fold higher in the 0.8 dS m-1 than 8.5 dS m-1 for both years. Linear reduction of total ET and trunk cross sectional area (TCSA) were observed while increasing ECiw from 0.8 dS m-1 to 8.5 dS m-1. The correlation between total ET and TCSA was stronger in the year 2009 than 2008. In agreement to the daily ET, a similar fluctuation of ECdw shown in the study, this was due to the influence of climate and tree growth on leaching fraction. Significantly higher ECdw were recorded at 8.5 dS m-1 than 0.8 dS m-1. Also similar fluctuation of crop coefficient (Kc) as daily ET was presented. Trees grown with ECiw of 0.8 dS m-1 showed higher Kc values than 8.5 dS m-1. Moreover the higher Kc values were presented in the year 2009 than 2008 under ECiw of 0.8, 1.2 and 2.8 dS m-1 but similar Kc values were presented at ECiw of 5 and 8.5 dS m-1 for both years. Measurement of total fruit yield showed a linear reduction in increasing ECiw levels. Fruit yield were reduced from 42,000 to 6,000 Kg ha-1 while increasing ECiw from 0.8 to 8.5 dS m-1. Besides, a tradeoff between the gross fruit yield and ECiw was experienced. Decreasing fruit yield was observed in increasing ECiw and vice versa. Based on the observation of various fruit quality parameters, improvement in overall fruit quality is not only possible by imposing salt stress but drought is helpful to some extent. An optimization among irrigation water quality, irrigation water regimes and fruit yield as well as various fruit quality parameters for instance fruit size, skin color, sugar and acid content, anthocyanin content, juice amount, antioxidant value etc need to be done for sustainable production

Mots Clés : Pomegranate — Effect of dought on. — Effect of salt on. — Effect of stress on.

Présentation (BGU)

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Page publiée le 7 janvier 2012, mise à jour le 22 novembre 2018