Assessment of discretely measured indicators and maximum daily trunk shrinkage for detecting water stress in pomegranate trees

8 páginas.-- 7 figuras.-- 3 tablas.-- 50 referenciasMeasurements obtained by the continuous monitoring of trunk diameter fluctuations were comparedwith discrete measurements of midday stem water potential and midday leaf conductance (gl)in adult pomegranate trees (Punica granatum L. cv. Mollar de Elche). Control plants (T0) were irrigateddaily above their crop water requirements in order to attain non-limiting soil water conditions in 2009 and 2010, while T1 plants were subjected to water stress by depriving them of irrigation water for34 days in 2010, after which time irrigation was restored and plant recovery was studied for 7 days.T1 plants showed a substantial degree of water stress, which developed slowly. Maximum daily trunkshrinkage (MDS) was identified to be the most suitable plant-based indicator for irrigation scheduling inadult pomegranate trees, because its signal:noise ((T1/T0):coefficient of variation) ratio was higher thanthat for midday stem water potential((T1/T0):coefficient of variation) and gl((T0/T1):coefficient of variation). MDS increasedin response to water stress, but when the stemfell below ¿1.67 MPa, the MDS values decreased. Fornon-limiting water conditions, MDS could be predicted from mean daily air temperature (Tm) throughexponential equations fitted to pooled data across several seasons. First-order equations were alsoobtained by pooling data across several seasons to predict MDS from crop reference evapotranspira-tion (ETo), mean daily air vapour pressure deficit (VPDm), Tmand solar radiation (Rs), but these should beused only within a certain range of values (ETo, 2.1¿7.4 mm; VPDm, 0.64¿2.96 kPa; Tm, 12.1¿28.3¿C; Rs,119.4¿331.3 Wm¿2). Hence, automated MDS measurements have the potential to be used in irrigationscheduling of pomegranate, and these values can be normalized to non-limiting water conditions bylocally derived empirical relationships with meteorological variables.This research was supported by Ministerio de Ciencia e Innovación (MICINN) (CICYT/FEDER AGL2010-19201-C04-01AGR) and Agencia Española de Cooperación Internacional para el Desarrollo (AECID) (A1/035430/11) grants to the authors

Changes in the Diversity of Soil Arbuscular Mycorrhizal Fungi after Cultivation for Biofuel Production in a Guantanamo (Cuba) Tropical System

The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems

Efecto del Quitomax en el crecimiento, las relaciones hídrica y el rendimiento y sus componentes en plantas de frijol (Phaseolus vulgaris L.) sometidas a dos manejos del agua de riego

Conferencia presentada en el XIX Congreso Científico Internacional del Instituto Nacional de Ciencias Agrícolas, At San José de las Lajas, Mayabeque (Cuba), Volume: EFV-P.01Con el objetivo de evaluar el efecto del QuitoMax en el crecimiento, las relaciones hídricas y en otras variables fisiológicas en plantas sometidas a dos niveles de abastecimiento hídrico, se realizó el presente trabajo en condiciones semicontroladas (canaletas) en el Instituto Nacional de Ciencias Agrícolas durante el período de enero a abril del 2013. Los tratamientos utilizados consistieron en dos controles sin aplicación del producto, uno en el que se le aplicó el agua equivalente al 100 % de la ETc y otro al que se le suministró el 50 % de la ETc y dos tratamientos en los que en ambos tratamientos de abastecimiento hídrico se aplicaron 200 mg.ha-1 de QuitoMax a los 23 días después de la siembra y otra similar al inicio de la floración. Los tratamientos fueron distribuidos en el campo de acuerdo a un diseño de bloques al azar con tres repeticiones, realizándose el análisis de los datos mediante un modelo de clasificación doble. Las variables evaluadas fueron: la longitud y el diámetro de los tallos, el número de foliolos, la superficie foliar, las masas secas de raíz, tallos y hojas, los potenciales hídrico foliar, osmótico actual, turgencia y osmótico saturado, la conductancia estomática, el número de vainas por planta, el número de granos por vaina, la masa fresca de 100 granos y el rendimiento estimado. De manera general las diferencias reflejadas por las variables del crecimiento son poco destacables desde el punto de vista biológico, las relaciones hídricas se manifestaron de acuerdo al abastecimiento hídrico recibido por las plantas, mientras que el rendimiento y sus componentes fueron favorecidos con la aplicación del QuitoMax en ambos manejos del agua de riego.EFV-P.01Peer Reviewe

Evidence of Differences between the Communities of Arbuscular Mycorrhizal Fungi Colonizing Galls and Roots of Prunus persica Infected by the Root-Knot Nematode Meloidogyne incognita▿

Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens

Long-term effects of irrigation with waste water on soil AM fungi diversity and microbial activities: the implications for agro-ecosystem resilience.

The effects of irrigation with treated urban wastewater (WW) on the arbuscular mycorrhizal fungi (AMF) diversity and soil microbial activities were assayed on a long-term basis in a semiarid orange-tree orchard. After 43 years, the soil irrigated with fresh water (FW) had higher AMF diversity than soils irrigated with WW. Microbial activities were significantly higher in the soils irrigated with WW than in those irrigated with FW. Therefore, as no negative effects were observed on crop vitality and productivity, it seems that the ecosystem resilience gave rise to the selection of AMF species better able to thrive in soils with higher microbial activity and, thus, to higher soil fertility

Number of clones detected for each fungal type in the native vegetation soil and <i>Ricinus communis</i> and <i>Jatropa curcas</i> soil (<i>n</i> = 5).

<p>Number of clones detected for each fungal type in the native vegetation soil and <i>Ricinus communis</i> and <i>Jatropa curcas</i> soil (<i>n</i> = 5).</p

Canonical correspondence analysis (CCA) of the different AMF sequence types and soil properties detected in the three soils studied.

<p>The eigenvalues of the first and second axes in the two-dimensional ordination diagrams are as follows: CCA1: 0.59 and CCA2: 0.55. C: native vegetation soil, R: <i>Ricinus communis</i> soil, J: <i>Jatropa curcas</i> soil, MBC:.microbial biomass C, CRL: colonized root length, AS: aggregate stability, OC: organic C, N: total N, EC: electrical conductivity.</p

Pearson's coefficients of correlation and significance level between the soil parameters measured, the root length colonised and the AMF diversity (n = 5).

<p>Pearson's coefficients of correlation and significance level between the soil parameters measured, the root length colonised and the AMF diversity (n = 5).</p

Biological, chemical and physical properties of native vegetation soil and <i>Ricinus communis</i> and <i>Jatropa curcas</i> soil (n = 5).

<p>Degree of AM fungal colonization in roots of <i>R. communis</i>, <i>J. curcas</i> seedlings and native vegetation soil.</p><p>MBC: microbial biomass C; Means ± standard errors; Values in row followed by the same letter do not differ significantly (<i>P</i><0.05) as determined by the LSD test.</p