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Background: Canopy architecture is critical in determining the fruit-zone microclimate and, ultimately, in determining an orchard's success in terms of the quality and quantity of the fruit produced. However, few studies have addressed how the canopy environment leads to metabolomic and transcriptomic alterations in fruits. Designing strategies for improving the quality of pear nutritional components relies on uncovering the related regulatory mechanisms. Results: We performed an in-depth investigation of the impact of canopy architecture from physiological, metabolomic and transcriptomic perspectives by comparing pear fruits grown in a traditional freestanding system (SP) or a flat-type trellis system (DP). Physiological studies revealed relatively greater fruit sizes, soluble solid contents and titratable acidities in pear fruits from DP systems with open canopies. Nontargeted metabolite profiling was used to characterize fruits at the initial ripening stage. Significant differences in fruit metabolites, including carbohydrates, nucleic acids, alkaloids, glycerophospholipids, sterol lipids, and prenol lipids, were observed between the two groups. Transcriptomic analysis indicated that a series of organic substance catabolic processes (e.g., the glycerol-3-phosphate catabolic process, pectin catabolic process and glucan catabolic process) were overrepresented in fruits of the DP system. Moreover, integrative analysis of the metabolome and transcriptome at the pathway level showed that DP pear fruits may respond to the canopy microenvironment by upregulating phenylpropanoid biosynthesis pathway genes such as PpPOD. Transient assays revealed that the contents of malic acid and citric acid were lower in the pear flesh of PpPOD RNAi plants, which was associated with regulating the expression of organic acid metabolism-related genes. Conclusions: Our results provide fundamental evidence that at the physiological and molecular levels, open-canopy architecture contributes to improving pear fruit quality and is correlated with increased levels of carbohydrates and lipid-like molecules. This study may lead to the development of rational culture practices for enhancing the nutritional traits of pear fruits. [ABSTRACT FROM AUTHOR]

Peach trees were trained to four systems, viz. Yshaped, Hedge row, Espailer and V trellis. Irrespective of the training system in upper canopy total PAR increased from January to July and then a decrease was recorded. However, in lower canopy an inverse trend was recorded. The total radiation intercepted during the year was maximum (59.99%) in Espailer system followed by V trellis (57.76%). Minimum radiation interception (49.05%) was recorded in trees trained to Hedge row. Upper canopy part of the tree received more PAR which influenced fruit quality in terms of size, weight, acidity, total sugars, firmness. [ABSTRACT FROM AUTHOR]

While the adoption of high-density apple orchards during the last decades has resulted in a significant improvement in yield and fruit quality, there is great disparity of opinion on the optimum density or the optimum tree shape. A 2-ha replicated field trial was planted in 1997 at the New York State Agricultural Experiment Station in Geneva, New York and continued through 2016, with 4 apple cultivars (‘Empire’, ‘Fuji’, ‘Gala’, and ‘McIntosh’), where we compared 8 tree planting densities (598, 840, 1026, 1283, 1655, 2243, 3262, and 5382 trees/ha), and two tree shapes (conic and V). At the lowest 2 densities, trees were planted on M.7 rootstock (598 trees/ha) and M.26 rootstock (840 trees/ha). At all of the higher tree densities, trees were planted on M.9. After 20 years, there was a strong negative correlation of tree planting density and trunk cross sectional area for all the cultivars and training systems, with the exception of ‘McIntosh’ in a V tree shape where no clear differences were observed. A different pattern for each cultivar was observed with respect to yield and planting density. High-density plantings were more appropriate for ‘Fuji’ and ‘Gala’, where conic tree shapes were better than V shapes. On the other hand, with ‘Empire’ and ‘McIntosh’ high planting density was not as beneficial. The highest yields from ‘McIntosh’ were realized at less than 3000 trees/ha with V tree shapes, or ∼3500 trees/ha with conic tree shapes. Planting density significantly affected firmness, soluble solids, fruit color, and fruit size. Light interception for each density and shape was measured only with ‘Empire’. Planting density had a strong positive effect on light interception. There were no significant differences in interception between tree shapes through the 4th leaf, however, after that more light was intercepted by the V shaped trees. Cumulative yield was a linear function of light energy intercepted by the canopy. While V tree shapes had more light interception, conic shapes seemed to have a better efficiency converting intercepted energy into yield. Planting density improved light interception, but decreased tree partitioning because of the need for more pruning leading to unbalanced trees. Tall Spindle at high planting density seemed to be the best option for cultivars with similar bearing habits such as ‘Fuji’ and ‘Gala’. [ABSTRACT FROM AUTHOR]

• Fruit trends and challenges for future peach production in Spain. • Labour is the main cost of production. • Vigour controlling rootstocks for getting early yields, reducing the cost of production, increasing fruit quality and labour efficiency. • Intensive training systems with planar canopies improved accessibility to labour and machines. In Spain, the total surface occupied by deciduous fruit species in 2019 was 190,414 ha. Peach is the second most important Prunus species with 77,464 ha and a production of 1,480,000 t per year. Labour is the main production cost, amounting to 45% of the total cost in 2020 and primarily involving pruning, thinning and harvesting. The common trend regarding agronomical orchard models, in deciduous fruit species, is planting intensification, combining mid to low vigour rootstocks and training systems based on small, bi-dimensional canopies. Size-controlling rootstocks such as Rootpac-40, Isthara or Adesoto-101, Among others, resulted in better yield efficiency and improved fruit quality compared with GF-677. In 7-year-old trees of 'Luciana' nectarine cultivar, the use of size-controlling rootstock Rootpac-40 and an intensive orchard trained in central leader allowed both earlier and higher yields, resulting in a difference of 102 tha−1 compared with the standard Spanish gobolet system on GF-677. With 'Noracila' and the same combinations, the difference was 109 tha−1. The central leader/single row and central leader/double row training systems, despite requiring a greater orchard establishment cost, gave earlier and higher yields in 'Ambra' and 'Luciana' cultivars grafted on G-677, around 48% for double row and 30% for single row, compared to the Spanish gobelet system. Planar canopies allowed an efficient use of mechanical and manual pruning and flower thinning, which improved harvest efficiency (kg.h−1) by 28%. As a result, a production cost reduction of around 15% was recorded in comparison to the Spanish gobelet system. Greater efficiency in total labour per season enabled a reduction of 39%, from 651 h.ha−1 for the Spanish gobelet system to 398 h.ha−1 for the central leader system. Additionally, an increase in fruit quality, particularly fruit size and SSC content, due to a more uniform light distribution was observed. In these planar intensive systems, including palmette, a reduction in light interception of 17% was recorded when compared to the open vase system. Yields obtained were more related to planting density and canopy architecture than the average of intercepted light. Currently, the central leader and bi-axis are the most important systems used in intensive orchards in Spain, with planting densities from 1,900 to 3,100 trees.ha−1. All these results support the sustainable intensification concept and make peach tree production more economically sustainable for growers. [ABSTRACT FROM AUTHOR]

An intensive field planting of ‘Edda’, 'Opal’ and 'Mallard’ plum trees (Prunus domestica L.) all grafted on the semidwarf rootstock St. Julien A was established in 1993 at Ullensvang Research Centre, western Norway at 60° North. Four different single row planting systems (vertical axis, free spindle, hedgerow and Y-trellis) and three planting densities (0.5, 1.0, 1.5×4 m for the Y-trellis and hedge trees and 2.0×4 m for the central leader trees) were evaluated. This field planting gave a rapid canopy development and crop yields at early tree age. Trunk cross sectional area of the trees increased with increasing tree spacing. ‘Opal’ was the most vigorous cultivar. During the first four cropping years, the yields/ha were positively correlated with tree density. After nine years, cumulative yield per ha was highest on the Y-trellis and hedge trees with the highest density (5000 trees per ha). The two central leaders showed similar yield pattern, but yielded less than the two other systems. Plums produced on these canopy systems showed minor differences in the average fruit weights, and no significant differences were found among the spacings. The soluble solid contents of the plums were in general high. Neither planting density nor system had much impact on the sugar content of these cultivars. ‘Opal’ had significantly smaller plums and lower contents of soluble solids than the two other cultivars. [ABSTRACT FROM AUTHOR]

Peach production in the USA has been in decline in recent decades due to poor fruit quality, reduced consumption and increased cost of production. Productivity and fruit quality can only be enhanced in the orchard through optimizing preharvest factors such as orchard design and training systems. Transition from low-density plantings (LDP) to high-density plantings (HDP) in peach is associated with the availability of reliable size controlling rootstocks. Increased densities must be combined with modern training systems to diffuse vigor and further increase light interception and yields, while optimizing light distribution, fruit quality and cost of production. Several training systems have been tested in peach with various objectives and goals, such as increasing light, water use and labor efficiencies, along with designing canopy architectures to facilitate mechanization and robotics. In general, increased planting densities increase yields, but excessive densities can promote shade, while excessive crop load can deteriorate quality. An ideal peach cropping system should optimize light interception and light distribution to balance maximum yield potential with maximum fruit quality potential. Successful management of high-density peach fruiting wall systems can lead to enhanced and uniform fruit quality, and ensure a sustainable industry. [ABSTRACT FROM AUTHOR]