The effects of different water stress (control, medium, and severe) on some morphological, physiological, and biochemical characteristics and bud success of M9 apple and MA quince rootstocks were determined. The results showed that water stress significantly affected most morphological, physiological, and biochemical characteristics as well as budding success on the both rootstocks. The increasing water stress decreased the relative shoot length, diameter, and plant total fresh and dry weights. Leaf relative water content and chlorophyll index decreased while electrolyte leakage increased with the increase of water stress in both rootstocks. An increase in water stress also resulted in reduction in budding success in Vista Bella/M9 (79.33% and 46.67%) and Santa Maria/MA (70.33% and 15.33%) combinations. However, the water stress in Santa Maria/MA was more prominent. The increase in water stress resulted in higher peroxidase activities as well as phenol contents in both rootstocks. Although catalase activity, anthocyanin, and proline contents increased with the impact of stress, this was not statistically significant. The results suggest that the impact of stress increased with the increase of water stress; therefore, growers should be careful when using M9 and MA rootstocks in both nursery and orchards where water scarcity is present.

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The aim of this study was to investigate long-term seasonal trends and decadal change patterns of monthly mean water vapor pressure (WVP) observation series at 16 meteorological stations scattered point-wisely over the Southeastern Anatolian Project (GAP) area in Turkey, where large-scale soil and water development projects have been put into practice since the 1970s. The record length of WVP observation series of each station varied between 31-and 41-years between 1962 and 2002. The monthly mean WVP observation series of each station was rearranged on seasonal basis. Sequential MannKendall trend test, Sen's slope estimator, and Spearman's rank-order correlation tests were employed for detection of likely trends, and Kruskall-Wallis test was used to detect decadal variations in WVP series of each observation station. A possible area of representation for each meteorological station was determined by using the Thiessen polygons technique in a geographical information systems media. It was found that 15 seasonal WVP series have a positive trend covering 97% of the GAP area in the summer season; although one WVP series has a negative trend direction. However, in the spring season, 33% of the area had a positive trend, and a negative trend did not appear in any stations. WVP records in the winter season showed an increasing trend over 19% of the GAP area, whereas a decreasing trend prevailed in 9% of the area. The study results led us to conclude that the substantial increase of WVP observations in summer season could be attributed to both the shift from rain-fed agriculture to irrigated agriculture being made increasingly spacious year by year and building large water reservoirs in the GAP located in a semi-arid region. The results also indirectly suggested that the historical trends in the WVP parameters might be related to global climate change phenomenon.

Water stress treatments on some morphological, biomass, physiological, biochemical characteristics and budding success of apricot and plum cultivars/Myrobolan 29 C plum rootstock have been studied in a pot-experiment trial. Three different water stress levels (control-100 %, medium-75 %, and severe-50 % of the pot capacity) were applied. The results showed that measured morphological, biomass, physiological and biochemical characteristics as well as budding success of cultivars on the rootstocks were affected by water stress. Water stress, both moderate and severe, significantly decreased the relative shoot length, diameter and shoot stem cross sectional area, plant total fresh and dry weights. Increases in water stress led to increases in peroxidase activities, phenol and proline contents in plum rootstock. Increases in water stress also resulted in reduction in budding success in both Formosa (plum cv)/Myrobolan 29 C (90.00 % and 48.33 %) and San Castrese (apricot cv)/Myrobolan 29 C (87.50 % and 42.83 %).Key words: antioxidant enzymes, apricot, budding success, rootstock, water stress.Résumé : Les auteurs ont étudié des traitements au stress hydrique pour certains paramètres morphologiques, physiologiques et biochimiques, la biomasse et le bourgeonnement des cultivars d'abricotier et de prunier sur le prunier porte-greffe Myrobolan 29 C dans le cadre d'un essai en pot. À cette fin, ils ont appliqué trois degrés de stress hydrique (témoin-100 %, modéré-75 % et grave-50 % de la capacité du pot). Les résultats indiquent que le stress hydrique affecte les paramètres associés à la morphologie, la biomasse, la physiologie et la biochimie de même qu'au bourgeonnement des cultivars sur porte-greffe. Un stress hydrique modéré ou grave réduit de manière significative la longueur, le diamètre ainsi que la surface transversale de la tige des pousses, le poids frais de la plante et son poids sec. La hausse du stress hydrique entraîne une plus grande activité de la peroxydase, de même que la concentration de conphénol et de proline chez le prunier porte-greffe. L'augmentation du stress hydrique entraîne de surcroît une diminution respective du bourgeonnement chez le cultivar de prunier Formosa/Myrobolan 29 C (90,00 % et 48,33%) et le cultivar d'abricotier San Castrese/Myrobolan 29 C (87,50 % et 42,83 %). [Traduit par la Rédaction]