Cristian Meriño-Gergichevich

Calcium sulfate ameliorates the effect of aluminum toxicity differentially in genotypes of highbush blueberry (Vaccinium corymbosum L.)

Abstract The effect of gypsum (CaSO 4 ) amendment in the reduction of Al phytotoxicity of blueberry cultivars differing in Al resistance (Legacy and Brigitta, Al-resistant and Bluegold, Al-sensitive) was studied in a Hoagland’s nutrient solution under acidic conditions for 2 weeks. Treatments were: Control (Hoagland solution), 2.5 mM CaSO 4 , 5 mM CaSO 4 , 100 µM Al (AlCl 3 ), 100 µM Al + 2.5 mM CaSO 4 , 100 µM Al + 5 mM CaSO 4 . Physiological, biochemical and chemical features of leaves and roots were determined to establish the amendment efficiency in the reduction of Al toxicity in these cultivars. Results showed that under Al toxicity the three investi-gated cultivars accumulated high Al concentrations in leaves and roots. These con-centrations decreased with CaSO 4 application. Statistically significant interactions among Al in leaves but not in roots ( p =0.719) and cultivars ( p <0.001), were found. The lowest Ca concentration was found in the most Al-sensitive cultivar (Bluegold) and the highest in the more Al-resistant cultivars (Legacy and Brigitta). Among the underlying processes affected by Al stress in these blueberry cultivars the most evident changes were exhibited by the Al-sensitive cultivar Bluegold, where the photosynthetic performance decreased showing a slight recovery in presence of gyp -sum amendment at the end of experiment. Instead, the more Al-resistant cultivar (Legacy) did not change its photosynthetic parameters in presence of the gypsum amendments during the treatment, whereas in Brigitta, only a slight recovery at the end of treatment was evidenced by the gypsum application. Thus, in relation to these parameters the gypsum amendment was efficient in complete recovery from the toxic Al effect in the Al-resistant cultivar Brigitta and a slight recovery of the toxic Al effect in the Al-sensitive cultivar Bluegold. Nonetheless, this amendment is a good alternative to ameliorate Al toxicity in Al-sensitive cultivars and additionally provides a good source of Ca and S.

Anatomical, physiological, and biochemical traits involved in the UV-B radiation response in highbush blueberry

The effects of a long-term simulated spring-summer UV-B daily course on some anatomical, physiological, and biochemical features were studied in new and old leaves of blueberry (Vaccinium corymbosum L.) cultivars Legacy, Brigitta, and Bluegold. The results show that under UV-B exposure, leaf thickness increased in Bluegold due to an increased intercellular cavities. By contrast, Brigitta maintained its leaf thickness. The net photosynthetic rate was not significantly affected by the UV-B radiation in any of the cultivars; however, Brigitta presented a better photosystem II performance, since this cultivar had more efficient photochemistry under the UV-B radiation. In addition, Brigitta also maintained enhanced total phenol and total anthocyanin content compared to the other cultivars. In conclusion, Brigitta was more resistant to the UV-B radiation than the other two cultivars.

Comparative study of methodologies to determine the antioxidant capacity of Al-toxified blueberry amended with calcium sulfate

Blueberry (Vaccinium corymbosum L.) is well adapted to acidic soils where aluminum (Al3+) can be linked to oxidative stress and antioxidant capacity (AC). Calcium sulfate (CaSO4) is used to alleviate Al3+ because it does not alter soil acidity. However, the role of Ca addition in AC, based on a single electron transfer reaction (SET), remains unknown.The aim was to evaluate the AC using SET methodologies, i.e., 2,2-diphenyl-2-picrylhydrazyl (DPPH), 2,2´-Azinobis-bis (3 ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing-antioxidant power (FRAP). Blueberry cultivars Elliot and Jersey were grown and exposed to the following treatments for 15 days: Control (nutrient solution alone, pH 4.5); control+Al (Al); control+Al+Ca (Al+Ca) and control+Ca (Ca). The Ca and Al concentrations, total phenol (TP) content and radical scavenging activity (RSA) were evaluated at 7 and 15 days. The Al+Ca and Ca treatments increased the Ca concentration in the leaves (22%) and roots (40%) of both cultivars compared with the control. The Ca in the tissues varied with cultivar and time. After 15 days, increases in TP, DPPH, ABTS and FRAP were detected. The cultivars showed positive relationships between the TP and AC in the leaves and roots. Thus, CaSO4 is an important tool to improve the AC in Al-stressed fruit crops grown in acid soils.

Physiological and nutritional responses in two highbush blueberry cultivars exposed to deficiency and excess of boron

Boron (B) is an essential micronutrient required for physiological and biochemical processes in fruit crops such as highbush blueberry (Vaccinium corymbosum L.), well adapted species to acidic soils (pHwater ≤ 5.5) with relatively low B availability. However, an optimal range of B supplies is quite narrow, particularly among cultivars, making it easy to underor over-fertilize which could lead to boron toxicity. Under controlled conditions, cultivars Brigitta and Legacy were grown in a peat moss substrate (pH 4.5) with five B concentrations (0, 50, 200, 400 and 800 μM). Plant biomass, nutrient concentration, water potential (Ψleaf), oxidative stress and antioxidant activity were determined at 30 d. Concentrations of 400 and 800 μM B reduced shoot and root growth in both cultivars, and 800 μM B decreased Ψleaf in Legacy and significantly increased it in Brigitta. Boron applied at 400 μM resulted in the highest B accumulation in leaves of Brigitta (5-fold) and Legacy (2-fold), whereas Brigitta roots showed up to 60% increased B accumulation in comparison with 50 μM B, respectively. High B caused more severe oxidative stress in leaves of Legacy than B deficiency. The antioxidant activity was increased from 50 to 400 μM B in both cultivars. Boron added at 400 and 800 μM impaired physiological and biochemical performance probably due to toxicity, demonstrating that highbush blueberry in a genotype-dependent manner has relatively low B requirement.

The effect of foliar boron spraying on the fruit features of Brigitta and Legacy highbush blueberry (Vaccinium corymbosum) cultivars

Boron (B) is associated with reproductive and antioxidant metabolism in plants, and in southern Chile, the deficiency of this micronutrient is ameliorated through foliar applications that are a part of agricultural management, thus ensuring the productivity of crops including highbush blueberry ( Vaccinium corymbosum L.). However, the appropriate B dosage for this species is unknown, so the aim of this study was to evaluate foliar B application on fruit quality in highbush blueberry in southern Chile. During the 2014-2015 season, Brigitta and Legacy cultivars were sprayed with B at rates of 0 (control), 200, 400 and 800 mg L-1 three times (10% bloom, full bloom, and fruit set), and fruit set (%), firmness (g mm-2), soluble solids (°Brix), weight (g) and size (mm) of the fruits were determined. In addition, antioxidant activity was measured by ORAC (oxygen radical absorbance capacity) and DPPH (2,2-diphenyl-1-picrylhydrazyl). The results showed that a low rate of B (200 mg L-1) increased the fruit set and soluble solids in Brigitta, whereas Legacy required higher B concentrations (400 and 800 mg L-1). In both cultivars, firmness, fresh fruit weight, dry matter (%) and antioxidant activity increased under the 200 and 400 mg B L-1 treatments, whereas this last parameter was reduced under a high B concentration. A low B rate showed to be more effective at improving fruit quality in Brigitta, while Legacy required higher B application rates. Future research should be performed over several seasons and different cultivars to confirm these results. El boro (B) esta asociado al metabolismo reproductivo y antioxidante en plantas. En el sur de Chile, su deficiencia es resuelta con aplicaciones foliares de este micronutriente como parte del manejo agronomico, asegurando asi la productividad en cultivos como arandano alto ( Vaccinium corymbosum L.). Sin embargo, la informacion sobre dosis adecuadas para esta especie es escasa. Se evaluo la aplicacion foliar de B sobre parametros de calidad en fruta de arandano alto del sur de Chile. En la temporada 2014-2015, plantas de cultivares Brigitta y Legacy, fueron asperjadas con B en dosis de 0 (control), 200, 400 y 800 mg L-1 en tres momentos durante la temporada (10% floracion, plena flor y fruto cuajado), determinandose: frutos cuajados (%), firmeza (g mm-2), solidos solubles (oBrix), peso (g) y calibre (mm), ademas de la actividad antioxidante mediante ORAC (oxygen radical absorbance capacity) y DPPH (2,2-diphenyl-1-picrylhydrazyl). Una baja dosis de B (200 mg L-1) incremento la cuaja y solidos solubles en Brigitta, mientras que Legacy requirio mayores concentraciones de B (400 y 800 mg L-1). En ambos cultivares aumento la firmeza, peso fresco y seco de la fruta, asi como la actividad antioxidante al ser tratada con 200 y 400 mg B L-1, mientras en alta concentracion disminuyo este ultimo parametro. Una baja dosis de B resulto ser efectiva mejorando la calidad de la fruta en el cultivar Brigitta, mientras que Legacy requirio dosis de B mas alta. Futuras investigaciones deberian ser realizadas en diferentes temporadas y cultivares para confirmar esta tendencia.