Heat-stress Tolerance of Some Strawberry (Fragaria × ananassa) Cultivars

Physiological parameters were used to investigate genotypic variations in 15 strawberry cultivars [‘Aromas’, ‘Camarosa’, ‘Carmine’, ‘Cal. Giant 3’ (CG3), ‘Cal. Giant 5’ (CG5), ‘Elsanta’, ‘Fern’, ‘Festival’, ‘Honeoye’, ‘Kabarla’, ‘Redlands Hope’ (R.Hope), ‘Ruby Gem’, ‘Selva’, ‘Sweet Charlie’ and ‘Whitney’] and their relationship to heat-stress tolerance (HST). Cold stored (frigo) strawberry seedlings were grown in pots for six weeks and then transferred to a growth chamber. The temperature in the growth chamber was increased stepwise from 35 to 40, 45 and 50 °C to create a heat-stressed environment. Leaf relative water content (RWC), loss of turgidity and chlorophyll content were measured at each temperature. The ‘Elsanta’ and ‘R.Hope’ had the highest RWC, while the ‘Festival’ and ‘CG3’ had the lowest. However, ‘Elsanta’ and ‘R.Hope’ had the lowest loss of turgidity, while ‘Festival’ and ‘CG3’ had the highest. ‘Elsanta’ and ‘R.Hope’ showed the lowest chlorophyll content, and ‘CG3’ and ‘Whitney’ had the highest. To determine HST (LT50), leaf discs of each cultivar were exposed to 35, 40, 45, 50, 55 and 60 °C. A considerable decrease in the LT50 was observed with increasing temperature in all cultivars. The LT50 of the cultivars ranged from 51.8 to 52.9 °C. Based on the data collected, ‘Elsanta’, ‘R. Hope’ and ‘Camarosa’ were determined to be relatively heat-tolerant cultivars, while ‘Whitney’, ‘Fern’, ‘Festival’ and ‘CG3’ were heat-sensitive cultivars.

Full Text:PDF

Field Evaluation of Traditional Apple Cultivars to Induced Diseases and Pests

During the survey we studied traditional old apple cultivars in order to test disease resistance, as part of an apple breeding program. Diseases and pests assessments were made throughout the two growing season in 2008 and 2009 in traditional apple cultivars (‘Batul’, ‘Pónyik’, and ‘Sóvári’) from stray and commercial (‘Golden Delicious’ and ‘Starkrimson’) apple orchards. Our data add to a body of evidence indicating that traditional apple cultivars under natural selection and without pesticide regime are highly and/or moderately resistant to fire blight, apple powdery mildew and apple scab. High resistance was observed for green apple aphid (‘Sóvári’) and rosy leaf-curling aphid (all cultivars, except ‘Sóvári’) throughout the assessment. Susceptibility from mediate to high level was observed for fruit peel moth and pear-leaf blister moth, while resistance and/or moderate resistance for spotted tentiform leafminer and codling moth. The codling moth damages were significantly correlated with seed number in fruits throughout the whole vegetation period. We can conclude that old apple cultivars sustained in their original regions could be a significant source of genes for apple breeding programs.

Full Text:PDF

Growth and Photosynthetic Characteristics of Two Strawberry Cultivars in Response to Furostanol Glycosides Treatments

Furostanol glycosides represent a large group of steroid compounds of plant origin with a broad spectrum of biological activities (anabolic, antioxidant, anti-fungal and nematicidal). Most of the research exhibits this effect in stress induced response on different pathogen attacks and only a few studies show the effect of glycoside on plants growth and development. In order to investigate the effects of furostanol glycoside treatment on rooting, growth performance and photosynthetic system efficiency, young unrooted strawberry plants (cv. ‘Real’ and ‘Magic’) were immersed in different concentrations (0.03 mM, 0.3 mM, 3 mM) of G1 solution (glycoside extracted from Lycopersicon sp.) and G2 (extracted from Digitalis sp.) and morphometric parameters were determined. The results showed that immersion in 0.3 mM glycoside solution improved the quality of strawberry planting material by increasing the number and length of roots, as well as by stimulating formation of new leaves. Moreover, the influence of foliar spraying with G1 and G2 on plants growth, assimilator pigments content and photosynthesis was determined. Foliar spraying with both glycosides solutions improved radicular growth and development, but dimensions of foliar apparatus increased only in G1 treated variants. Although both glycoside treatments induced an increase in assimilator pigments content, photosynthetic rate decreased as a consequence of stomatal limitations associated with better efficiency of water use and of internal CO2, which suggests that these chemicals may have an antitranspirant action.

Full Text:PDF