This paper reviews field measurements of evapotranspiration from paddy rice fields (ET) in an experimental station in the Gharb region of Morocco, during the summer seasons in 1995 and 1996. The results showed that the seasonal average water consumption of rice was 6.7 mm•day-1 with a maximum value of 8.3 mm•day-1 during the panicle enlargement stage (R2). The average daily ET for 1996 was compared with US Class 'A' open pan evaporation (Ep) and with reference evapotranspiration (ET 0) calculated using a validated FAO Penman-Monteith equation. Both methods gave good estimates of ET with a correlation coefficient of 0.78 (P < 0.001, slope = 1.06) with Ep and 0.79 with ET 0 (P < 0.001, slope = 1.3). The derived mean crop coefficients were 1.06 and 1.3, respectively, for the average of the two years. The cumulated ET over the growing season was nearly equal to the cumulated Ep, and greater by about 20% of cumulated ET 0. This superiority might be attributed to an advective energy transferred from areas surrounding the rice zone activated by wind speed. rice (Oryza sativa) evapotranspiration / crop coefficient / reference ET Résumé-Calcul de l'évapotranspiration du riz sous les conditions marocaines : recherche d'une relation simple entre l'évapotranspiration calculée expérimentalement et l'évapotranspiration de référence estimée à partir de l'équation FAO Penman-Montheith et l'évaporation bac. Cet article traite de l'évapotranspiration du riz (ET) mesurée expérimentalement au niveau du champ dans la région rizicole au nord-ouest du Maroc durant la période estivale de 1995 et 1996. Les résultats obtenus ont été comparés à ceux de l'évaporation à partir d'un bac ouvert class 'A' (Ep) et avec l'évapotranspiration de référence calculée à partir de l'équation FAO Penman-Monteith (ET 0) calibrée sous les conditions marocaines. Les résultats obtenus ont été comparés à l'ET 0 et à l'Ep. Des coefficients culturaux ont été alors établis. Les résultats obtenus ont montré que la moyenne saisonnière des besoins en eau du riz était de 6,7 mm•jour-1 avec un maximum atteint de 8,3 mm•j-1 durant la deuxième décade du grossissement de la panicule avant l'épiaison. L'ET saisonnière en 1996 a montré une corrélation très hautement significative avec les deux modèles, de 0,78 (P < 0,001, pente = 1,06) avec Ep et 0,79 avec ET 0 (P < 0,001, pente = 1,3). les coefficients culturaux moyens des deux années, étaient respectivement de 1,06 (Kcp = ET•Ep-1) et 1,3 (KC 0 = ET•ET 0-1). L'ET cumulée durant la saison de croissance égalise avec l'Ep cumulée et dépasse l'ET 0 cumulée de 20 %. Cette supériorité pourrait provenir d'une énergie advective transmise des zones sèches, entourant la zone rizicole, activée par le déplacement des vents. riz (Oryza sativa) évapotranspiration / coefficient cultural / évapotranspiration de référence
One of the common features of the Mediterranean climate in North Africa is the uncertainty of rainfall immediately after wheat (Triticum durum Desf) emerges. Relatively little work has been done to compare the drought resistance of spring durum wheat cultivars under early-season drought stress. There is a limited insight into the physiological basis of spring durum wheat drought resistance in rainfed Mediterranean regions. Field experiments were conducted in 1995 and 1996 growing seasons, and a greenhouse experiment was conducted in 1996 to examine differences in some physiological characters among six spring durum wheat cultivars in response to different durations of early-season drought, and rewatering; and to determine the relationships of these characters to drought resistance. Six spring durum wheat cultivars were evaluated under four water regimes. Water regime treatments were: a well-irrigated treatment; and three water deficit treatments imposed during the period from emergence through either the onset of tillering, mid-tillering or the end of tillering. Cultivars differed widely in their response to early season water stress. Under drought stress conditions, grain yield, aboveground dry matter yield, water use efficiency for the grain (WUEg) and for the total dry matter (WUEdm) were strongly positively associated with net CO2 uptake:transpiration ratio (A/E), and osmoregulation capacity. It is concluded that drought-induced changes in A, A/E, stomatal resistance, and osmotic adjustment are possible key control points in determining the drought-resistance of a cultivar. Furthermore, there is a substantial degree of intraspecific variation for the above mentioned physiological attributes to explore as a selection tool. Selection for high osmoregulation capacity and high A/E ratio would seem to be a justifiable means of improving total dry matter and grain yield under conditions of early-season water stress. Key words: Wheat, Triticum durum Desf., physiological attributes, early-season drought
A pool of genetic variability is a prerequisite for any practical approach to improving crop salt tolerance. The objective of this study was to determine how epinasty, a morphological response of tomato to salt stress, can be used as a measure of salt tolerance and how it is related to ethylene production and water relations in tomato. Three Lycopersicon esculentum cultivars (Edkawy, Ramy, and Vemar) and one Lycopersicon sheesmanii accession were subjected to four levels of salt stress at the roots (0, 50, 100, and 200 mM NaCl). Epinasty increased with increasing levels of salinity depending on genotype, leaf age and duration of the salt stress. Relative ethylene production by tomato petioles also increased with the intensity of salt stress, genotype and leaf age; salt tolerant varieties exhibited less epinasty and a lower relative ethylene production. epinasty / ethylene / salt stress / tomato Résumé-Effet du stress salin sur l'épinastie en relation avec la production d'éthylène et les relations hydriques chez la tomate. La recherche de la variabilité génétique est l'approche la plus efficiente pour améliorer la tolérance des cultures à la salinité. L'objectif de cette étude est de déterminer comment l'épinastie, une des réponses morphologiques de la tomate au stress salin, peut être utilisée comme critère de tolérance à la salinité. Pour atteindre cet objectif, trois cultivars de Lycopersicon esculentum (Edkawy, Ramy et Vemar) et une accession de Lycopersicon sheesmanii ont été soumis à 4 niveaux de salinité (0, 50, 100 et 200 mM de NaCl). Les données ont montré que l'épinastie a augmenté avec l'augmentation des niveaux de salinité. Son amplitude a dépendu du génotype, de l'âge de la feuille et de la durée du stress. Parallèlement, la production relative d'éthylène était fonction du niveau du stress salin, du génotype et de l'âge la feuille. Les génotypes tolérants ont manifesté, sous stress salin, une faible épinastie et une faible production relative d'éthylène (% de témoin).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.