Responses of Papaya Seedlings (Carica papaya L.) to Water Stress and Re-Hydration: Growth, Photosynthesis and Mineral Nutrient Imbalance |
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Authors: | Jalel Mahouachi Ana Rosa Socorro Manuel Talon |
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Institution: | (1) Departamento de Suelos y Riegos, Instituto Canario de Investigaciones Agrarias, Apdo 60, E–38200 La Laguna, Santa Cruz de Tenerife, Spain;(2) Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias, E-46113 Moncada, Valencia, Spain |
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Abstract: | The effects of water stress and subsequent re-hydration on growth, leaf abscission, photosynthetic activity, leaf water potential
and ion content were investigated in papaya seedlings (Carica papaya L.) cv. “Baixinho de Santa Amalia”. Water stress was imposed by suspending irrigation during 34 days. Thereafter, plants
were regularly re-watered. Drought arrested plant growth, induced leaf abscission and drastically decreased photosynthetic
rate. However, leaf water potential was hardly reduced. Water deficit also induced sodium, potassium and chloride accumulation
in leaves and roots, and did not modify nitrogen levels in both organs. Re-hydration stimulated growth, promoted emergence
of new leaves, reactivated photosynthetic machinery function and reduced ion content to control levels. The results indicated
that the ability of papaya plants to improve drought tolerance is not mediated through the reduction of leaf abscission, the
detention of growth or the decrease of net CO2 assimilation. In contrast, the data suggested that under water stress conditions these plants appear to posses a certain
capacity to increase ion content, which might contribute to osmotic adjustment. |
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Keywords: | abscission chloride photosynthesis potassium sodium water stress |
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