The Influence of Biostimulants on Tomato Plants Cultivated under Hydroponic Systems

Two biostimulants, RutfarmMaxifol (Ascophyllum nodosum extract 17.5%, amino acids, macro- and microelements, Agromaster, Russia) and Radifarm (polysaccharides, glycosides, amino acids, and micro-elements; Valagro, Italy), were applied at different concentrations on tomato plants of the hybrid cultivar ‘Merlice’, grown under a hydroponic system. Biostimulants were applied in the form of seed soaking and twice as foliar sprayings at flowering and at the initial fruit development stages. Biostimulants were applied as water solutions at concentrations of 2.5, 5.0, and 7.5 mg·L−1. Plant growth, productivity, and fruit quality parameters were determined at three points: 35, 70, and 105 days after seeding. All biostimulant treatments resulted in higher values of growth parameters and yield productivity in relation to the control. The application of biostimulants improved the parameters of the fruits’ quality by increasing the total soluble solids and antioxidants, ascorbic acid, and carotenoid contents but it did not affect tomato fruit acidity; therefore, tomato fruits from the treated plants were tastier than those from control.

Influence of irrigation regimes on yield, pomological parameters and population development of Tetranychus cinnabarinus Boisd. (Acari: Tetranychidae) in strawberry

In this study, the effect of full (IR100), 50% (IR50), 75% (IR75) and 125% (IR125) irrigation levels on population development of the carmine spider mite (CSM) as well as on yield and some pomological properties of ‘Fortuna’ strawberry cultivar grown in high tunnels were evaluated in two consecutive growing seasons (2016–2017 and 2017–2018). The numbers of CSM were significantly lower on strawberry leaves which were irrigated by IR50 and IR75 in both growing seasons. Full (IR100) and highest (IR125) irrigation levels were the most favorable for the development of CSM populations. On the other hand, in the CSM thriving period (2017), the fruit weight was generally high in the plots with the highest irrigation (IR125) level. Although there was no interaction with the CSM population, fruit acidity (%) increased in the IR100 and IR125 irrigation levels, possibly due to stress in plants, when CSM population was highest (in March). In the absence of CSM, fruit acidity was significantly high in the plots where water stress was experienced. While no significant interaction was found between the pomological characters and the CSM population, the mites affected the yield significantly in that plants were more productive under IR 75 even when there was a CSM population. This study suggests that the application of IR75 level in Fortuna strawberry is related to lower CSM population growth and significantly higher yields.

Leaf Removal Applied to a Sprawling Canopy to Regulate Fruit Ripening in Cabernet Sauvignon

Under the effects of climate change, it is becoming increasingly common to observe excessively fast grape sugar accumulation while phenolic and flavour development are lagging behind. The aim of this research was to quantify the impacts of three different leaf removal techniques on the canopy architecture and ripening of Cabernet Sauvignon trained in a sprawl trellis system. Treatments were performed at veraison (~14 °Brix) and included (i) control; (ii) leaf plucking in the bunch zone; (iii) leaf plucking the top two-thirds of shoots, apical to the bunches; and (iv) shoot trimming. On the date of harvest, no significant difference in total soluble solids was observed between treatments. Other results including the effect of the treatments on fruit acidity, anthocyanins, phenolics, and tannins were somewhat inconclusive. While various other studies have shown the potential of leaf removal to achieve slower grape sugar accumulation without affecting the concentration of anthocyanins, phenolics, and tannins, the results of this study do not indicate a decrease in the rate of grape sugar accumulation as a result of the investigated defoliation techniques. Given the cost of implementing these treatments, the results of this study do not support the use of these methods for the purpose of delaying fruit ripening in a hot Australian climate.

Classifying Cider Apple Germplasm Using Genetic Markers for Fruit Acidity

The organic acid concentration in apple (Malus ×domestica) juice is a major component of hard cider flavor. The goal of this study was to determine if the malic acid markers, Ma1 and Q8, could classify the titratable acidity concentration in cider apple accessions from the United States Department of Agriculture Malus germplasm collection into descriptive classifications. Our results indicate that for diploid genotypes, the Ma1 marker alone and the Ma1 and Q8 markers analyzed together could be used to predict cider apple acidity (P < 0.0001). Alone, the Ma1 marker categorized acidity into low (<2.4 g⋅L−1), medium (2.4–5.8 g⋅L−1), and high (>5.8 g⋅L−1) groups. The combination of Ma1 and Q8 markers provided more specificity, which would be useful for plant breeding applications. This work also identified a significant difference (P = 0.0132) in acidity associated with ploidy. On average, the triploids accessions had 0.33 g⋅L−1 higher titratable acidity than the diploid accessions. Based on the results of this work, we propose a genetics-based classification system for cider apples with the acidity component defined by the Ma1 and Q8 markers.

Paclobutrazol in the flowering management affects the quality of Malpighia emarginata fruits

ABSTRACT Floral management using the growth regulator paclobutrazol may be an alternative for promoting the uniformity of flowering and fruiting in West Indian cherry (Malpighia emarginata D.C.) plants. However, the effects of its use on fruit quality are still unknown. This study aimed to evaluate the effect of paclobutrazol doses on the fruit quality of M. emarginata. The experimental design was randomized blocks, in a 2 x 5 factorial arrangement, with three replications and three plants per plot, with the studied factors consisting of two M. emarginata cultivars ('Junko' and 'Flor Branca') and five paclobutrazol doses (0, 0.4, 0.8, 1.2 and 1.6 g a.i. m-1 of canopy diameter). The following variables were evaluated: fruit mass, fruit transverse and longitudinal diameters, pH, soluble solids content, titratable acidity, soluble solids/titratable acidity ratio and vitamin C content. The use of paclobutrazol, to some extent, promoted the increase of fruit mass, longitudinal diameter and soluble solids contents. The 'Junko' cultivar presented a higher vitamin C content than that for 'Flor Branca', and the maximum vitamin C contents were obtained with the paclobutrazol doses of 0.64 and 0.81 g a.i. m-1, respectively for the 'Junko' and 'Flor Branca' cultivars. None of the studied factors promoted differences for pH and fruit acidity.