WATER STRESS OF ALFALFA DURING STRESS AND RECOVERY

1982 ◽  
Vol 62 (3) ◽  
pp. 639-647 ◽  
Author(s):  
ROBERT G. HALL ◽  
KENNETH L. LARSON
Keyword(s):  
Water Stress ◽  
Medicago Sativa ◽  
Developmental Stages ◽  
Water Status ◽  
Leaf Conductance ◽  
Daily Maximum ◽  
Full Bloom ◽  
Water Deficits ◽  
Medicago Sativa L

Water status and stomatal activity of alfalfa (Medicago sativa L.) cultivars Cody and Sonora were evaluated under greenhouse conditions during water stress and recovery at the 7th leaf and full bloom developmental stages. Following onset of stress predawn LWP declined linearly and plants remained visibly wilted as potentials approached 1.8 MPa in both cultivars and developmental stages. Significant (P = 0.05) relationships were evident between predawn LWP and days after onset of stress (R2 > 0.90) and between daily maximum leaf conductance (KL) and predawn LWP (R2 > 0.80) when averaged over both cultivars at each stage. Recovery of LWP of both cultivars was complete within 24 h after rewatering. Ability of stomatal activity to recover was similar for both cultivars and developmental stages and was attained within 32 h after rewatering. Results indicate that these cultivars, which differ in winterhardiness, do not differ in water status and stomatal activity with increasing water deficits.

scholarly journals Photosynthetic parameters of Juglans nigra trees are linked to cumulative water stress

2019 ◽  
Vol 49 (7) ◽  
pp. 752-758
Author(s):  
Martin-Michel Gauthier ◽  
Douglass F. Jacobs
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Net Photosynthesis ◽  
Juglans Nigra ◽  
Future Research ◽  
Photosynthetic Parameters ◽  
Water Deficits ◽  
Growth And Survival ◽  
Physiological Processes ◽  
Influence Of Water

The influence of water deficits and drought on tree physiological processes, growth, and survival has been the focus of substantial research efforts and debate over the past decades, but there is still a need to quantitatively link finer scale mechanistic explanations of the influence of water status with the physiological responses of trees, particularly for those past the sapling stage. Hence, the objective of this study was to link accumulated water stress during the growing season to leaf physiological response mechanisms of Juglans nigra L. trees. Results showed that trees subjected to higher cumulative water stress had lower maximum light-saturated photosynthesis (Amax), initiated net photosynthesis at higher light levels (Ic), and displayed reduced effectiveness of CO2 fixation per photons absorbed (Qe) at the bottom and upper positions along the vertical canopy gradient. Results suggest that water stress integral (Sψ), a variable that takes into account accumulated water deficits, would be useful to help future research efforts aimed at investigating responses to drought in trees past the sapling stage.

scholarly journals EFEITO DO ESTRESSE HÍDRICO E DOSES DE POTÁSSIO NA PRODUTIVIDADE DA ALFAFA (Medicago sativa L.)

Irriga ◽  
2000 ◽  
Vol 5 (2) ◽  
pp. 110-118
Author(s):  
Hatiro Tashima ◽  
Antonio Evaldo Klar
Keyword(s):  
Water Stress ◽  
Medicago Sativa ◽  
Nitrogen Concentration ◽  
Water Levels ◽  
The Other ◽  
Natural Soil ◽  
The Third ◽  
Aerial Parts ◽  
Medicago Sativa L ◽  
Nitrogen Contents

EFEITO DO ESTRESSE HÍDRICO E DOSES DE POTÁSSIO NA PRODUTIVIDADE DA ALFAFA (Medicago sativa L.)  Hatiro TashimaFundação Faculdade de Agronomia “Luiz Meneghel”, DEER,  Cx. Postal 261, CEP 86.350 -000, Bandeirantes - Pr - Fone: (0xx43) 543 8046 - E'mail: [email protected] Evaldo Klar2Dep. de Eng. Rural -FCA -UNESP - Cx. Postal 237 - CEP 18603-970 - Botucatu - SPFone: (0xx14) 6820 - 7165; Fax: 6820 - 7194 -E'mail: [email protected]  1 RESUMO Foi estudada, em condições de campo, a produtividade da alfafa (Medicago sativa L.) submetida  a cinco níveis de água e quatro doses de potássio. O delineamento experimental foi inteiramente ao acaso em um esquema fatorial 5x4 com 3 repetições.  Os níveis de água foram definidos como A1, A2, A3, A4 e A5, os quatro primeiros  corresponderam às tensões mínimas de -0,01; -0,05; -0,1; -1,5 MPa, respectivamente, e o nível A5 recebeu apenas água da chuva. As doses de potássio foram definidas como: K1 correspondeu o teor natural de potássio no solo (2,5 mmolc dm-3), K2, K3 e K4 corresponderam as aplicações de 117,3; 351,9 e 821,1 g de K / parcela de 6 m2, respectivamente.O experimento foi avaliado do terceiro até o oitavo corte. Pelos resultados obtidos, pode-se concluir que: as combinações entre níveis de água A2 e A3 com doses de potássio K3 e K4 produziram maior quantidade de massa seca no  total de seis cortes; os níveis de água não afetaram a concentração do nitrogênio (N) na parte aérea, exceto no 6º corte em que o tratamento A5 foi significativamente superior  e no 7º o tratamento A4 foi significativamente inferior em relação a outros tratamentos; as maiores doses de potássio aplicadas no solo propiciaram maiores teores do elemento na parte aérea da  planta, no entanto verificou que a concentração do nitrogênio diminuiu.   UNITERMOS: Alfafa, estresse hídrico, potássio.  TASHIMA, H., KLAR, A. E. Effect of water stress and potassium doses on alfalfa (Medicago sativa L .) yield.  2 ABSTRACT             This study was developed to evaluated the effect on alfalfa (Medicago sativa L) of four minimum soil water potentials (MPa): - 0.01 (A1); - 0.05 (A2); 0.1 (A3); 1.5 (A4) and A5, without any irrigation and four doses of potassium (mmol/dm3 ): K1 – 2.5 natural soil content; K2 – 117.3;  K3 – 351.9; K4 – 821.1 of K per plot of 6 m2. The harvest was divided in 8 cuts, but only 6 of them were evaluated, from the third to eight.            The combinations among A2 and A3 with K3 and K4 resulted on higher dry material of plants; water levels did not affected nitrogen concentration of plants, except the 6th cut, when A5 showed significantly higher and A4, at the 7th cut,lower values in relation to the other treatments. The highest potassium doses showed highest potassium doses in aerial parts of plants, but decreased the nitrogen contents. KEYWORDS: alfalfa, water stress, potassium.

scholarly journals Forage productivity of alfalfa (Medicago sativa L.) in the pedo-climatic conditions from

2012 ◽  
Vol 69 (1) ◽  
Author(s):  
Mihai STAVARACHE ◽  
Vasile VáŽNTU ◽  
Costel SAMUIL ◽  
Iulian MUNTIANU ◽  
Constantin Iulian POPOVICI ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Dry Matter ◽  
Growth Stage ◽  
Climatic Conditions ◽  
Control Plot ◽  
Full Bloom ◽  
Shoot Ratio ◽  
Medicago Sativa L ◽  
Second Year

The research in the period 2010-2011, within the Ezareni Farm from Iasi, were focused on the influence of inoculation, fertilization and harvesting growth stage on the leaf/shoot ratio and dry matter (DM) yield, at alfalfa ( medicago sativa L.) in the second year after sowing at the first harvest. The results indicated that the interaction between inoculation, fertilization and harvesting growth stage determined increases of yield in the range of 23-110%. The control plot where fertilization was not applied, without inoculation, which was harvested at early bud registered the lowest yield, 3.21 t/ha D.M., and the biggest yield (6.72 t/ha) was registered at the plot with inoculation, fertilized with N 75P50, harvested at 10% blooming. The leaves/shoots ratio registered differences in the range of +11% to -42%, accordingly to the interaction between the inoculation, fertilization and harvesting growth stage. The highest leaves/shoots ratio, 0.64% was observed at the plot with inoculation, unfertilized, harvested late bloom, and the lowest leaves/shoots ratio (0.33) was observed at the plot without inoculation, fertilized with N 75P50 harvested at full bloom.

scholarly journals Impacts of water stress, environment and rootstock on the diurnal behaviour of stem water potential and leaf conductance in pistachio (Pistacia vera L.)

2016 ◽  
Vol 14 (2) ◽  
pp. e0804 ◽  
Author(s):  
Houssem Memmi ◽  
Jose F. Couceiro ◽  
Carmen Gijón ◽  
David Pérez-López
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Leaf Conductance ◽  
Irrigation Season ◽  
Stem Water Potential ◽  
Stem Water ◽  
Diurnal Behaviour ◽  
Pistachio Trees

Little information is available on the diurnal behaviour of water potential and leaf conductance on pistachio trees despite their relevance to fine tune irrigation strategies. Mature pistachio trees were subject to simultaneous measurements of stem water potential (Ψx) and leaf conductance (gl) during the day, at three important periods of the irrigation season. Trees were grown on three different rootstocks and water regimes. An initial baseline relating Ψx to air vapor pressure deficit (VPD) is presented for irrigation scheduling in pistachio. Ψx was closely correlated with VPD but with a different fit according to the degree of water stress. No evidence of the variation of Ψx in relation to the phenology of the tree was observed. Furthermore, midday Ψx showed more accuracy to indicate a situation of water stress than predawn water potential. Under well irrigated conditions, gl was positively correlated with VPD during stage II of growth reaching its peak when VPD reached its maximum value (around 4 kPa). This behaviour changed during stage III of fruit growth suggesting a reliance of stomatal behaviour to the phenological stage independently to the tree water status. The levels of water stress reached were translated in a slow recovery of tree water status and leaf conductance (more than 40 days). Regarding rootstocks, P. integerrima showed little adaptation to water shortage compared to the two other rootstocks under the studied conditions.

Estimación de biomasa aérea de forrajes de invierno bajo riego a través de un dron

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Francisco Gavi Reyes ◽  
César Botello-Aguillón ◽  
Leonardo Tijerina-Chávez ◽  
Arturo Galvis-Spíndola ◽  
Rodrigo Roblero-Hidalgo
Keyword(s):  
Medicago Sativa ◽  
Avena Sativa ◽  
Medicago Sativa L

E Objetivo: Desarrollar un procedimiento para estimar biomasa con imágenes digitales captadas desde un dron y modelación 3D (ID-Dron-3D) aplicable en alfalfa (Medicago sativa L.) y avena forrajera (Avena sativa L.). Diseño/metodología/aproximación: Con una cámara digital acoplada al dron se obtuvieron imágenes antes de la cosecha de los cultivos, que fueron procesadas con software para luego estimar volumen de biomasa. En cada cultivo se midió altura de la planta y área cosechada, volumen aparente y real de biomasa, y peso de biomasa fresca y seca. Resultados: Con base en el análisis de regresión se obtuvieron modelos lineales a una p<0.05 para predecir: biomasa fresca en avena (R2=0.70) y alfalfa (R2 =0.47); y biomasa seca en avena (R2=0.78) y en alfalfa (R2=0.31) mediante ID-Dron-3D. Limitaciones del estudio/implicaciones: Considerando las R2 de los modelos obtenidos, los resultados en la avena forrajera fueron mejores, respecto a los detectados en alfalfa, lo cual se puede deber a la mayor variabilidad de la cobertura vegetal, ya que, en algunas unidades de muestreo, las plantas de alfalfa no cubrían completamente el suelo. Hallazgos/conclusiones: El rendimiento de biomasa fresca y seca de ambos cultivos se correlacionó significativamente con su respectivo volumen aparente estimado con imágenes digitales tomadas desde un dron y su procesamiento 3D (ID-Dron-3D).

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