Massimo Noferini

Perspectives on the use of a seaweed extract to moderate the negative effects of alternate bearing in apple trees.

Summary Alternate bearing is a serious problem in many apple varieties. In fact, each year, apple trees have to be thinned in order to ensure a correct and constant balance between the reproductive and vegetative tendencies of the plant. In organic fruit growing, there is no alternative to the expensive and time-consuming process of hand-thinning. Under these conditions, the use of natural bio-stimulants which enhance the efficiency of nutrient uptake, plant fitness to different pedoclimatic conditions, and plant tolerance to stress, offers new opportunities to reduce the negative effects of alternate bearing. The aim of this work was to evaluate the effects of Actiwave®, a metabolic enhancer derived from the alga, Ascophillum nodosum, on ‘Fuji’ apple trees affected by experimentally-imposed alternate bearing. The experiments were carried in open field conditions over four consecutive years. Although the effect of Actiwave® was erratic from year-to-year, the compound generally reduced those problems linked to alternate bearing. Actiwave® had its most significant effect on alternate bearing plants that were also affected by nutrient deprivation due to the absence of fertilisation. In these trees,Actiwave® decreased the oscillations in yield between “on” and “off” years and increased the average fruit weight on plants affected by too-high a crop load. Treated trees also showed higher leaf chlorophyll contents (increased by 12%), with a consequent increase in the rates of photosynthesis and respiration. On the other hand, under standard conditions, in well-fertilised balanced plants, Actiwave® did not have any significant effect. This evidence corroborates the hypothesis that Actiwave® may be a useful tool to reduce alternate bearing in organic and low-input farming.

On the role of ethylene, auxin and a GOLVEN-like peptide hormone in the regulation of peach ripening

BackgroundIn melting flesh peaches, auxin is necessary for system-2 ethylene synthesis and a cross-talk between ethylene and auxin occurs during the ripening process. To elucidate this interaction at the transition from maturation to ripening and the accompanying switch from system-1 to system-2 ethylene biosynthesis, fruits of melting flesh and stony hard genotypes, the latter unable to produce system-2 ethylene because of insufficient amount of auxin at ripening, were treated with auxin, ethylene and with 1-methylcyclopropene (1-MCP), known to block ethylene receptors. The effects of the treatments on the different genotypes were monitored by hormone quantifications and transcription profiling.ResultsIn melting flesh fruit, 1-MCP responses differed according to the ripening stage. Unexpectedly, 1-MCP induced genes also up-regulated by ripening, ethylene and auxin, as CTG134, similar to GOLVEN (GLV) peptides, and repressed genes also down-regulated by ripening, ethylene and auxin, as CTG85, a calcineurin B-like protein.The nature and transcriptional response of CTG134 led to discover a rise in free auxin in 1-MCP treated fruit. This increase was supported by the induced transcription of CTG475, an IAA-amino acid hydrolase. A melting flesh and a stony hard genotype, differing for their ability to synthetize auxin and ethylene amounts at ripening, were used to study the fine temporal regulation and auxin responsiveness of genes involved in the process. Transcriptional waves showed a tight interdependence between auxin and ethylene actions with the former possibly enhanced by the GLV CTG134. The expression of genes involved in the regulation of ripening, among which are several transcription factors, was similar in the two genotypes or could be rescued by auxin application in the stony hard. Only GLV CTG134 expression could not be rescued by exogenous auxin.Conclusions1-MCP treatment of peach fruit is ineffective in delaying ripening because it stimulates an increase in free auxin. As a consequence, a burst in ethylene production speeding up ripening occurs. Based on a network of gene transcriptional regulations, a model in which appropriate level of CTG134 peptide hormone might be necessary to allow the correct balance between auxin and ethylene for peach ripening to occur is proposed.

Determination of harvest maturity of D'Agen plums using the chlorophyll absorbance index

R. Infante, P. Rubio, L. Contador, M. Noferini, and G. Costa. 2011. Determination of harvest maturity of D’Agen plums using the chlorophyll absorbance index. Cien. Inv. Agr. 38(2): 199-203. The objective determination of the optimal harvest date for plums intended either for industrial processing or for consumption as fresh fruit is a fundamental concern of the fruit industry. A portable visible/near infrared (Vis/NIR) spectroscopic device was used to sort D’Agen plums harvested around the traditional commercial harvest date. The chlorophyll absorbance index was found to be capable of segregating plums into classes of maturity according to various concentrations of soluble solids and fruit compression strenght values. Fruits with a chlorophyll absorbance index value of less than 1.59 showed no differences in flesh firmness. Plums harvested with chlorophyll absorbance index values of 1.20-1.29 had a fruit compression strenght of 1.25 N and a soluble solids concentration of 23.3%. Both of these values correspond to adequate thresholds for harvesting plums for industrial purposes. The chlorophyll absorbance index may be valuable in allowing the identification of high-quality plums either for fresh consumption or industrial processing.

Non-destructive Assessment of Highbush Blueberry Fruit Maturity Parameters and Anthocyanins by Using a Visible/Near Infrared (vis/NIR) Spectroscopy Device: A Preliminary Approach

We evaluate the use of a portable and non-invasive technology based on visible and near infrared (vis/NIR) spectroscopy (Cherry-Meter) for monitoring fruit maturity parameters and anthocyanins in two highbush blueberry (Vaccinium corymbosum L.) cultivars (Misty and Sharpblue). This device measures an Index of Absorbance Difference (I AD ), which showed high correlations with fruit quality parameters in other fruit crops. We found positive but differential correlations between I AD values and fruit anthocyanins, which was higher for Misty (r = 0.970, p≤0.01) than for Sharpblue (r = 0.714, p>0.05). Interestingly, Cherry-Meter measurements were also correlated with solid soluble concentrations (r = 0.685, p≤0.01) and fruit firmness (r = -0.714, p≤0.01), but only in Sharpblue. For both cultivars, I AD values were also significantly (p≤0.01) related with fruit FW (0.447 for Sharpblue and 0.559 for Misty). The High Performance Liquid Chromatography (HPLC) data indicated that I AD variations were associated with significant changes in single berry anthocyanidins levels. These findings are the first approach, highlighting the potentialities of Cherry-Meter for the non-destructive assessment of fruit maturity and anthocyanidin profile in blueberries.

1-MCP effects on ethylene emission and fruit quality traits of peaches and nectarines

1-methylcyclopropene (1-MCP), an ethylene antagonist, is an effective device to improve the shelf life and quality of fruits, vegetables and ornamentals. It also represents an useful tool in studies aimed at clarifying the ethylene physiology in plants. Peaches and nectarines are climacteric fruits which exhibit a sharp rise in ethylene synthesis at the onset of ripening associated with changes in colour, texture, aroma and other biochemical features. Therefore, treatments with ethylene antagonist such as 1-MCP has been performed for extending post-harvest storage and shelf life of peach fruit. Fruit developmental stage must be considered when applying 1-MCP, as its effects vary with fruit maturity. In fact, the efficacy of 1-MCP treatment decreases with advanced fruit development. In order to study the effects of 1-MCP on peaches and nectarines at different ripening stages, the fruit was divided into homogeneous classes by using a non-destructive technology (NIRs = near-infrared spectroscopy). This technology allowed to correlate the difference of absorbance at two specific wavelengths (DA index) to ethylene emission levels in peach fruit. Immediately after harvest, three groups of fruit were set, with different AD index intervals: the first one included ‘pre-climacteric’ fruit, characterised by very low or undetectable ethylene emission levels, the second one included ‘early-climacteric’ fruit (low ethylene emission levels) and the third one ‘late-climacteric’ fruit (high ethylene emission levels). The fruit of the three classes was treated with 1-MCP (1 μl l) for 12 h at 25°C. Treated and control fruit was then kept at 25°C for about 1 week and the effects on ethylene emission and fruit quality traits (flesh firmness, total soluble solids content, titratable acidity) were evaluated.