Fruit quality of Redhaven and Royal Glory peach cultivars on seven different rootstocks

Two peach cultivars, Redhaven and Royal Glory, grafted on seven different rootstocks (Adesoto, Barrier 1, GF 677, Ishtara, Monegro, Penta, and peach seedling) were analyzed for tree vigor and yield. Fruit of similar ripeness (fruit firmness) was analyzed in terms of pomological (fruit weight, soluble solids content) and biochemical parameters (individual sugars, organic acids, phenolic acids in the flesh and peel, as well as flavonols and anthocyanins in the peel). A uniform effect of rootstock on tree size was evident in the cases of both cultivars. The Ishtara rootstock induced weak tree growth; Adesoto, Penta and peach seedling semivigorous growth; and Barrier 1, GF 677, and Monegro vigorous tree growth. We recorded higher yields in the Redhaven cultivar, while no significant differences in yield in the fourth growing season were found among the rootstocks for each cultivar. Rootstock had no effect on soluble solids in the Redhaven cultivar, while in the Royal Glory it did. Penta yielded the highest soluble solids content levels, while Adesoto and Monegro were associated with low levels. In the fruit from both cultivars, the rootstock had a significant influence on individual sugars, organic acids, and phenolic acids in the pulp. We also found that phenolic acids in the pulp and skin were more affected by the rootstock than other secondary metabolites analyzed, regardless of the cultivar.     

Bending affects phenolic content of William pear leaves

Abstract

The effect of branch bending on the phenolic content in pear leaves was investigated. Leaves were sampled from the tree branches which were bent in summer 2003 (1 September), in spring 2004 (15 May), and from unbent trees. Samplings were made during the growing season May to October 2004, on the following dates: 1st sampling, 15 May; 2nd sampling, 11 June; 3rd sampling, 9 July; 4th sampling, 6 August; 5th sampling, 2 September; and 6th sampling, 1 October. The leaves contained caffeic acid, chlorogenic acid, sinapic acid, syringic acid, vanillic acid, rutin, epicatechin and catechin. The lowest contents of phenolics were found on the first occasion. After that, in the sequence of sampling dates, an increase was noticed at first, but after reaching their highest point, the contents of phenolics decreased. In most cases fewer contents of phenolic compounds were found in leaves from bent branches (especially from branches bent in summer), and the highest ones in leaves from the control group. For all phenolics, apart from the caffeic and vanillic acids, significant differences were evident among treatments, with the highest contents in the control group and almost the lowest in the summer treatment. It is suggested that the change in branch angle caused the physiological response of pear tree, with different contents of phenolic compounds in its leaves from bent and non-bent branches.     

Changes in phenolic content induced by infection with Didymella applanata and Leptosphaeria coniothyrium,the causal agents of raspberry spur and cane blight

The phenolic profile of healthy and infected raspberry canes was investigated in three raspberry cultivars: Autumn Bliss, Himbo Top and Polka. The content of total phenols and tannins was determined using spectrophotometric methods, whilst individual phenolic acids, flavan‐3‐ols, ellagic acid derivatives and glycosides of quercetin were analysed using HPLC/MS analysis. The content of secondary metabolites varied considerably among the analysed raspberry cultivars. Moreover, Didymella applanata and Leptosphaeria coniothyrium infection significantly altered the metabolism of phenolic compounds. Flavanols represented the greatest share of all identified phenolics in raspberry canes (90%), followed by glycosides of quercetin (6%), derivatives of ellagic acid (3%) and traces of hydroxycinnamic acid derivatives. Spur and cane blight diseases caused an increase of flavan‐3‐ols and tannins but the levels of hydroxycinnamic acid derivatives, conjugates of ellagic acid and quercetin glycosides were significantly reduced. Cultivars Himbo Top and Polka contained higher levels of hydroxycinnamic acid and ellagic acid derivatives in healthy and infected canes compared to cv. Autumn Bliss. Cultivar Polka also contained the highest level of flavanols and tannins. However, despite high levels of flavanols and total phenols measured in cv. Polka, the canes were highly diseased following infection with D. applanata and L. coniothyrium. The results of the study provide evidence that the level of phenolic compounds in the canes could be causally linked to the differences in disease susceptibility.