José Ignacio Covarrubias

Physiological and biochemical responses of the iron chlorosis tolerant grapevine rootstock 140 Ruggeri to iron deficiency and bicarbonate

Background and aimsIron (Fe) deficiency chlorosis associated with high levels of soil bicarbonate is one of the main nutritional disorders observed in sensitive grapevine genotypes. The aim of the experiment was to assess both the independent and combined effects of Fe and bicarbonate nutrition in grapevine.MethodsPlants of the Fe chlorosis tolerant 140 Ruggeri rootstock were grown with and without Fe(III)-EDTA and bicarbonate in the nutrient solution. SPAD index, plant growth, root enzyme (PEPC, MDH, CS, NADP+ −IDH) activities, kinetic properties of root PEPC, organic acid concentrations in roots and xylem sap and xylem sap pH were determined. A factorial statistical design with two factors (Fe and BIC) and two levels of each factor was adopted: +Fe and −Fe, and +BIC and −BIC.ResultsThis rootstock strongly reacted to Fe deficiency by activating several response mechanisms at different physiological levels. The presence of bicarbonate in the nutrient solution changed the activity of PEPC and TCA related enzymes (CS, NADP+-IDH) and the accumulation/translocation of organic acids in roots of Fe-deprived plants. Moreover, this genotype increased root biomass and root malic acid concentration in response to high bicarbonate levels in the substrate. Bicarbonate also enhanced leaf chlorophyll content.ConclusionsAlong with a clear independent effect on Fe nutrition, our data support a modulating role of bicarbonate on Fe deficiency response mechanisms at root level.

Postveraison Shoot Trimming Reduces Cluster Compactness without Compromising Fruit Quality Attributes in Organically Grown Sangiovese Grapevines

Vine performance following preveraison shoot trimming is well documented, but the consequences of this treatment later in the season are poorly understood. Here, a four-year study was conducted in a mature vineyard of Sangiovese (clone 12T) grafted onto Kober 5BB rootstock at a spacing of 1 m × 2.8 m (intra- and interrow) to analyze the influence of postveraison shoot trimming on vine growth characteristics, cluster architecture (cluster compactness), and yield from a physiological viewpoint. The treatments consisted of shoot trimming during postveraison in a randomized block design with eight replications (six vines each). Three treatments were imposed when soluble solids reached 15 Brix in August (40 to 45 days before expected harvest): light trimming (14 nodes), severe trimming (10 nodes), and an untrimmed control. Following the treatments, vine growth characteristics, cluster morphology, and fruit quality attributes were measured. Postveraison shoot trimming (especially severe trimming) reduced cluster weight, cluster compactness, productivity, and total yield. Effects on fruit quality included lowering of Brix and pH, with minor effects on titratable acidity, yeast assimilable nitrogen, the anthocyanin profile, and total anthocyanins. These results demonstrated that postveraison shoot trimming can be a valuable production practice by reducing cluster compactness without compromising overall fruit quality in Sangiovese.

Organic acids metabolism in roots of grapevine rootstocks under severe iron deficiency

Background and aimsIn many important viticultural areas of the Mediterranean basin, plants often face prolonged periods of scarce iron (Fe) availability in the soil. The objective of the present work was to perform a comparative analysis of physiological and biochemical responses of Vitis genotypes to severe Fe deficiency.MethodsThree grapevine rootstocks differing in susceptibility to Fe chlorosis were grown with and without Fe in the nutrient solution.ResultsRootstock 101-14, susceptible to Fe chlorosis, responded to severe Fe deficiency by reducing the root activity of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH), however, it accumulated high levels of citric acid. By contrast, rootstock 110 Richter, tolerant to Fe chlorosis, maintained an active metabolism of organic acids, but citric acid accumulation was lower than in 101-14. Similarly to 101-14, rootstock SO4 showed a strong decrease in PEPC and MDH activities. Nevertheless it maintained moderate citric acid levels in the roots, mimicking the response by 110 Richter.ConclusionsRoot PEPC and MDH activities can be used as tools for screening Fe chlorosis tolerance. Conversely, organic acids accumulation in roots may not be a reliable indicator of Fe chlorosis tolerance, particularly under conditions of severe Fe deficiency, because of their probable exudation by roots. Our results show that drawing sound conclusions from screening programs involving Fe deficiency tolerance requires short as well as long-term assessment of responses to Fe deprivation.

CHANGES IN PHYSICAL PROPERTIES OF A TYPIC HAPLOCAMBID BY ANNUAL CROP CULTURE

As an alternative to organic soil amendments used in the Copiapo Valley (northern Chile), this study analyzed the magnitude of changes in physical soil properties associated with different crop rotations on the rows on a grape orchard. The study was performed in the locality of Los Loros, Atacama Region, during the 2006-2008 seasons. In a Typic Haplocambid soil (2-5% slope, coarse loam) with a 6-year old grape plantation, a control and three crop rotations were established, each with four replicates. Soil samples were taken at three depths (0-10; 10-40; 40-60 cm), evaluating bulk density, penetration resistance, aggregate stability, pore size distribution and air and water flux. Crop rotation did not produce statistical differences in soil density compared with the control treatment; nevertheless, soil mechanical strength decreased compared to the control without crops. Aggregate stability increased on the surface horizon when Poaceae and Fabaceae were used separately, but not when they were planted together. Below the surface this effect vanished and no significant differences were observed compared with the control. The leguminous crops promoted a more continuous porous system, with an increase of coarse porosity and a higher air and water flux capability. A longer time period of crop rotation is required to improve the productive potential of grapes.

Physical properties of a fine textured haplocambid after three years of organic matter amendments management

AbstractIn Copiapo Valley, the 3 th Region of Chile, a three-year study (2007-2009) was conducted to evaluate the effect of organic amendments and cover crops on soil physical properties (Typic Haplocambid) in a table grape ( Vitis vinifera ) orchard. Four treatments were established during three seasons: control without organic amendments (T1), broad bean-corn-rape rotation (T2), goat manure addition (15 t ha -1 ) (T3) and corn-broad bean-barley rotation (T4). Soils measurements, bulk density, pore size distribution, aggregate stability, water repellence and air conductivity were conducted on soil samples collected at three soil depths (0-10, 10-30 and 30-50 cm). Saturated hydraulic conductivity and mechanical strength were also evaluated. On grape plant measurements, root development, pruning weight and harvested grape production were evaluated. Soil bulk density was reduced with goat manure addition in comparison with any other treatment, which resulted in lower mechanical strength in the top soils. None of the treatments had negative effects on water repellency. The crop treatments enhanced the coarse porosity throughout the soil profile, improving the continuity of porous system with their root development and inducing high air conductivity. Other hand, the control soil and manure application showed a pore discontinuity in a pre-existing plow pan. Aggregate stability and saturated hydraulic conductivity were greater in goat manure application, but the treatments which included crop rotation did not show significant differences compared with the control. Because of the short duration of the study, it is assumed that the soil improvements were not detected as expected in grape production yet. Keywords: Compaction, cover crops, aggregate stability, soil porosity

Control of plant-parasitic nematodes using cover crops in table grape cultivation in Chile

A study to evaluate the effect of a three-year rotation with cover crops for the management of plant-parasitic nematodes (PPNs) was performed in two vineyards producing table grapes ( Vitis vinifera L.) in a semiarid region in the north of Chile. In the first vineyard, located in Copiapo valley (trial I), the crops used in the rotations or monoculture were fava bean ( Vicia faba ) cv. Aguadulce, rape ( Brassica napus var. napus ) cv L-456, forage turnip ( B. rapa var. rapa ) cv. Barkant, barley ( Hordeum vulgare ) cv. Aurora, oat ( Avena sativa ) cv. Urano-INIA, and mustard greens ( Brassica juncea ). At the second vineyard employed in the study, located in Huasco valley (trial II), the same crops and varieties were used in a rotation system with the incorporation of crop/goat manure mixtures or manure only at a rate of 10 Mg ha -1 . In both studies, two control treatments were included: a nontreated control and a chemical control in which ethoprop was applied at a rate of 7 kg ha -1 . The results from trial I indicated no significant differences between the cover crop rotation treatments and controls for Xiphinema index and for the other PPNs populations. In trial II, treatments 4 (manure) and 5 (manure and crop rotation) showed significantly lower values compared to treatment 2 (chemical control), with the highest X. index levels, but no differences from the control. No differences were detected for the other PPNs. Se realizo un estudio destinado a evaluar el efecto de cultivos de cobertura en rotacion durante tres anos, sobre el control de nematodos fitoparasitos en dos plantaciones de uva de mesa en una region semiarida del norte de Chile. La primera plantacion correspondio a un parronal en Copiapo (ensayo I), donde los cultivos utilizados en rotacion o en monocultivo fueron haba ( Vicia faba ) cv. Aguadulce; raps ( Brassica napus var. napus ) cv L-456; rabano forrajero ( B. rapa var. rapa ) cv. Barkant; cebada ( Hordeum vulgare ) cv. Aurora; avena ( Avena sativa ) cv. Urano-INIA y mostacilla ( Brassica juncea ). El segundo parronal utilizado para el estudio esta ubicado en la localidad de Huasco (ensayo II), donde se utilizaron los mismos cultivos y variedades, en un sistema de rotacion, incorporandose ademas una mezcla de cultivos sembrados sobre guano de cabra y guano de cabra solo, en dosis de 10 Mg ha -1 . En ambos estudios se incluyo un control absoluto y un control quimico, ethoprop, en una dosis de 7 kg ha -1 . Bajo las condiciones de este estudio, los resultados indican que en el ensayo I, no hubo diferencias significativas en los tratamientos basados en los cultivos de cobertura en rotacion y el control de poblaciones de Xiphinema index asi como en el resto de los fitoparasitos. En el ensayo II, solo se observan diferencias entre los tratamientos en base solo a guano y guano y rotaciones con el tratamiento quimico, siendo este ultimo el menos efectivo de todos los tratamientos. En el resto de los fitoparasitos, no hay diferencias despues de tres anos de evaluaciones.