Relationship between fruit weight and the fruit-to-leaf area ratio, at the spur and whole-tree level, for three sweet cherry varieties

Fruit weight is the main quality parameter of sweet cherries and leaf area/fruit is the most important characteristic influencing fruit weight. The objective of this study was to determine the relationship between Mean Fruit Weight (MFW) and the Fruit Number to Leaf Area Ratio (FNLAR) for `Bing¿, `Van¿ and `Lapins¿, grown under tatura-trellis and vase training systems, at both the spur and whole-tree level. The research was performed through regression analysis with FNLAR as the independent variable and MFW as the dependent variable. There were no significant interactions between training system and cultivar for the effect of FNLAR on MFW at either the spur or whole-tree level. Also, there were no significant differences between training systems. The R2 for the relationships per cultivar were higher at the whole-tree level than at the spur level. At both levels, `Lapins¿ had the highest fruit weight potential and `Van¿ the lowest. At the spur level, the slopes of the regression were similar for the different cultivars, but at the whole-tree level, `Van¿ was less sensitive. The better fit at the whole-tree level suggests that fruits of a spur are supplied not only by the leaves on that spur, but also from other less fruit-loaded spurs, from non-fruiting shoots and from reserve

Fruit dry weight and quality of 'bing' sweet cherries grown without source limitations

Understanding the seasonal pattern of potential fruit growth is important for identification and timing of possible management operations, and quantification of this pattern is an important prerequisite to serve as input for crop growth models. `Bing¿ sweet cherry trees were heavily thinned at 63 degree-days (DD) (=8 days) after full bloom so weight and quality of the remaining fruit could be monitored under conditions of limiting and non-limiting carbohydrate supply. The effect of fruit thinning on mean shoot growth and trunk cross-sectional area also was analysed to detect possible translocation from reproductive to vegetative growth. Mean Fruit Dry Weight (MFDW) of tagged fruit was estimated weekly, based on fruit diameter, to identify the moment of the onset of competition between fruit within trees. At harvest, Fruit Number to Leaf Area Ratio (FNLAR, fruits m-2 LA) was 52% lower in heavily-thinned trees than in non-thinned trees. Yield per tree was higher (

Estimation of Leaf area in sweet cherry using a non-destructive method

Leaf area measurement can be a time consuming process and requires sophisticated electronic instruments. The objective of this research was to develop a simple, accurate, non-destructive and time saving predictive model for leaf area (LA) estimation in sweet cherry trees. Linear regression equations were fitted and evaluated for three cultivars and two training systems using alternatively the length (L), the width (W) and their product (L*W) as independent variables. Regression using L*W variable fitted the data better (R2 = 0.994) than L or W (R2 = 0.863 and 0.787, respectively). The slopes using L*W as the explanatory variable were between 0.6776 and 0.6442 for different combinations of cultivar and training system. Combinations of cultivar training system showed different slopes (P<0.05), except for «tatura-Bing» and «vase-Lapins». A general equation had a slope of 0.6612 with R2 = 0.993 (slightly lower than considering all combinations of cultivar and training system). Validation of the general equation using extra data from a «Lapins/ Mahaleb» orchard showed high accuracy (R2 = 0.9826), but underestimated LA. However, the general equation can be used for predicting LA for practical purposes, such as estimating Leaf Area Index of commercial orchards

Effect of fruit-to-leaf area ratio on fruit quality and vegetative growth of 'bing' sweet cherry trees at optimal leaf area index

Fruit yield and quality determine grower income from commercial sweet cherry orchards. The objective of this study was to determine the effect of Fruit Number to Leaf Area Ratio (FNLAR, fruit m-2 LA) on Mean Fruit Weight (MFW), firmness (F), soluble solids content (SSC), titratable acidity (TA) and SSC:TA ratio of `Bing¿ sweet cherries trees of near-optimal leaf area index (LAI). The effect of FNLAR on Mean Shoot Growth (MSG) and trunk cross-sectional area increment (TCSAI) also was analysed to determine possible competition between reproductive and vegetative growth. Regression analysis was used with FNLAR as the independent variable. While SSC:TA, MSG and TCSAI were not significantly correlated to FNLAR (P>0.05), MFW, TA and SSC decreased linearly with increasing FNLAR (

Sweet cherry production in South Patagonia

In South Patagonia, the total sweet cherry (Prunus avium L.) area has increased from 176 ha in 1997 to 507 ha in 2004, of which 232 ha are located in Los Antiguos (46°19¿ SL; 220 m elevation), 158 ha in the Lower Valley of Chubut River (LVCHR) (43°16¿ SL; 30 m elevation), 52 ha in Sarmiento (45°35¿ SL; 270 m elevation), 35 ha in Esquel (42°55¿ SL; 570 m elevation) and 30 ha in Comodoro Rivadavia (45°52¿ SL; 50 m elevation). The most common varieties are `Lapins¿, `Bing¿, `Newstar¿, `Sweetheart¿, `Stella¿, `Sunburst¿ and `Van¿ grafted on `Mahaleb¿, `Pontaleb¿, `SL 64¿, `Colt¿ or `Mazzard¿ rootstocks. Trees generally are drip-irrigated and planted at high densities, using training systems such as Tatura, central leader and modified vase (2700, 1100 and 1000 trees ha-1, respectively). Growers in Los Antiguos are more traditional, planting mainly as vase (400 to 1000 trees ha-1) or freestanding trees (280 trees ha-1) and irrigating by gravity (74% of the area). Only 4.4% of the area of Los Antiguos is frost protected, as growers rely strongly on the moderating effect of Lake Buenos Aires. Frost control systems are absent in Comodoro Rivadavia because the established orchards are located next to the sea, in an area with low risk of frost. The frost-protected area is 49% in Sarmiento, 35% in Esquel and 57% in LVCHR. Fruit are harvested from November (LVCHR) to the end of January (Los Antiguos and Esquel), and the harvest-only labour demand during the 2004/2005 season was 100,000 h. In that season, seven packinghouses exported 390 t (45% of the total production) to Europe. Most orchards have not yet reached their mature stage and new ones are being established. Therefore, fruit volumes will continue to increase and shortages of labour and packing facilities may become a constraint

Sweet cherries from the end of the world: options and constraints for fruit production systems in South Patagonia, Argentina

In South Patagonia, development of the fruit production sector has been almost exclusively based on the production of sweet cherry, with an area increase from 176 ha in 1997 to 578 ha at the end of 2006. These orchards are designed as intensive systems and oriented to export markets. Even though sweet cherry seems currently the most profitable crop in the region, other crops may be interesting to increase the use efficiency of the resources, to complement income and to spread risk. The general objective of this thesis was to assess constraints and opportunities for fruit production systems in Chubut and Santa Cruz Provinces, with emphasis on sweet cherry. In the context of cherry production for export, it is important to define fruit quality and how this can be affected. Although quality has different meanings for different stakeholders, consumer acceptance seems to be the most important factor to be considered, but independent of consumer liking, firmness is a key aspect for marketing cherries overseas. To estimate the optimal combination of yield and fruit quality, a “target-tree” approach to maximize gross value of product (GVP) at farm gate was developed and applied to cherry orchards, integrating eco-physiological information, model estimates and expert knowledge. Minimum fruit quality thresholds define the suitable market for the fruit, with their associated price ranges. In addition, on both domestic and export markets, price depends mainly on fruit size. The fruit number to leaf area ratio determines fruit quality (and indirectly fruit price), but in combination with mean fruit weight and leaf area index, also yield. GVP is calculated as the product of yield and fruit price. Quantification of frost damage risk is important in planning the development of new orchards and to decide on design and installation of frost control systems. Therefore, a comprehensive method to quantify frost damage risk was developed and the potential impact of frost control systems on risk reduction was estimated. Frost damage for any specific day of the season was assumed to occur when the minimum temperature on that day was below the specific lethal temperature for the phenological stage predicted at that moment. Frost damage probability was estimated for each production location of the region as the frequency of years in which at least one damaging frost occurs, at any time during the growing season until harvest. Frost damage risk was compared among cultivars and locations, and also the effect of active frost control methods on frost damage risk reduction was analyzed. Due to the long lifespan of orchard systems, an explorative modelling study was performed. OPTIFROP is a dynamic farm model, developed as an Interactive Multiple Goal Linear Program, capable of allocating, throughout the time horizon of the run, production activities to different land units, while optimizing different (conflicting) objectives, subject to several constraints. For deriving land use options and quantifying the TCs, a software called FRUPAT was developed. This allows combining crop-tree species, edaphic environment, training, irrigation and frost control system, and moment of installation of the frost control system. Feasible land use options were completely characterised by their inputs and outputs at each orchard age until their maximum lifespan. The aim of OPTIFROP was to support strategic decision-making, such as ‘when to plant’, ‘what to plant’, ‘with which technology’, and ‘how much area of each activity’. Thus, the model allowed identification of the options for development plans for Patagonian farms (‘window of opportunities’). The model allowed quantifying the trade-off between conflicting objectives. The different methods developed in this thesis contribute significantly to the fruit industry in South Patagonia by supporting growers, extensionists and researchers in developing structured thinking for analyzing and processing available (fragmented) information