Fruit Thinning and Shade Improve Bean Characteristics and Beverage

Journal of the Science of Food and Agriculture J Sci Food Agric 86:197–204 (2006) DOI: 10.1002/jsfa.2338

Fruit thinning and shade improve bean characteristics and beverage quality of coffee (Coffea arabica L.) under optimal conditions Philippe Vaast,1,2∗ Benoit Bertrand,2 Jean-Jacques Perriot,2 Bernard Guyot2 and Michel Genard´ 3 1Centro Agronomico´ Tropical de Investigacion´ y Ensenanza˜ (CATIE), Apdo 3, 7170 Turrialba, Costa Rica 2Centre de Cooperation´ Internationale en Recherche Agronomique pour le Developpement´ (CIRAD), 2477 Avenue du Val de Montferrand, BP 5035, F-34032 Montpellier, France 3Institut National de la Recherche Agronomique (INRA), Plantes et Systemes` de Cultures Horticoles, Domaine Saint-Paul Agroparc, F-84914 Avignon Cedex 9, France

Abstract: Under two contrasting light regimes (full sun and 45% shade) and the optimal coffee-growing conditions of the central valley of Costa Rica, production pattern, bean characteristics and beverage quality were assessed over two production cycles on dwarf coffee (Coffea arabica L. cv. Costa Rica 95) trees with varying fruit loads (quarter, half and full loads) imposed by manual fruit thinning. Shade decreased coffee tree productivity by 18% but reduced alternate bearing. Shade positively affected bean size and composition as well as beverage quality by delaying berry ﬂesh ripening by up to 1 month. Higher sucrose, chlorogenic acid and trigonelline contents in sun-grown beans pointed towards incomplete bean maturation and explained the higher bitterness and astringency of the coffee beverage. Higher fruit loads reduced bean size owing to carbohydrate competition among berries during bean ﬁlling. These results have important implications in terms of agricultural management (shade, fruit thinning, tree pruning) to help farmers increase coffee plantation sustainability, produce coffee beans of larger size and higher quality and ultimately improve their revenues, especially during times of world overproduction.  2005 Society of Chemical Industry

Keywords: bearing pattern; bean biochemical content; berry maturation; coffee beverage quality; fruit load; shade

INTRODUCTION Arabica coffee (Coffea arabica L.) is a cash crop Until recently the emphasis in coffee research has of major economic importance in Central American focused mainly on orchard management practices countries, which have a long-lasting reputation for to increase coffee productivity and on breeding pro- producing coffee of high quality. In this region, grammes to enhance resistance to pests and diseases. Arabica coffee was traditionally grown under shade in Owing to the current low market prices caused by complex agroforestry systems with up to three storeys world overproduction, there is a strong interest in of vegetation.7 In the late 1970s, however, the rapid producing and marketing coffee of higher quality to development of leaf rust disease (Hemileia vastatrix)led alleviate financial difficulties encountered by coffee to the planting of a new generation of resistant, dwarf farmers. Coffee quality is mainly assessed through the cultivars. Compared with traditional ones, these dwarf physical aspects of coffee beans such as bean colour, cultivars have a more compact canopy and shorter size, density and percentage of physical defects in branches, allowing higher planting densities under producing countries, whereas cup quality is the main their own dense shade and hence increased production criterion in consuming countries. Numerous factors per hectare.8 This has radically modified agricultural affect coffee quality,1 including soil water status,2 practices, especially pruning and fertilisation regimes, climatic conditions,3,4 maturity of coffee berries at and often resulted in the complete elimination of shade harvest and bean processing (fermentation, washing, trees. However, these full-sun and intensively managed drying, storage, roasting, beverage preparation), agri- coffee systems are not recommended in the absence cultural management (shade, pruning, fertilisation) of optimal ecological conditions. Furthermore, these and genetic properties of cultivars.5,6 systems are not only more economically risky but

∗ Correspondence to: Philippe Vaast, Centro Agronomico´ Tropical de Investigacion´ y Ensenanza˜ (CATIE), Apdo 3, 7170 Turrialba, Costa Rica E-mail: [email protected] Contract/grant sponsor: European Commission; contract/grant number: CASCA ICA4-CT-2001-10071 Contract/grant sponsor: Science and Cultural Cooperation Centre, French Embassy, Costa Rica (Received 23 March 2004; revised version received 7 December 2004; accepted 25 May 2005) Published online 10 October 2005  2005 Society of Chemical Industry. J Sci Food Agric 0022–5142/2005/$30.00 197 P Vaast et al. also less ecologically sustainable. The presence of 1/2, half of initial fruit load; 1/4, quarter of initial shade trees is known to improve soil organic fruit load) were imposed on the coffee trees, resulting matter content, alleviate high solar irradiance, buffer in six combinations of light levels and fruit loads detrimental diurnal changes in air temperature and with 16 replicates per combination. Fruit thinning was humidity9 and reduce nutrient leaching, especially performed manually a few days after flowering at the nitrate which contaminates aquifers.10 Additionally, beginning of the 1999 and 2000 production cycles. products derived from associated timber and fruit trees In 2001, fruit thinning was not undertaken, to test help farmers to diversify their income. Finally, shade the effects of previous fruit loads on tree productivity. trees play an important role in the region owing to the Furthermore, only coffee production was assessed for valuable impact of coffee agroforestry systems on the this third production cycle (2001). environment and natural resources (preservation of biodiversity, soil conservation, water quality, carbon Leaf area, leaf-to-fruit ratio, leaf temperature sequestration). Recent studies in Guatemala11 and and irradiance measurements Costa Rica12 have demonstrated that elevation and The area of individual leaves was measured with shade improved coffee quality owing to cooler climatic a LICOR 1800 area meter (LICOR, Lincoln, NE, conditions and probably a longer ripening period of USA). Measurements were performed on three coffee berries. In 1999 a collaborative research effort branches (branch positions 10, 17 and 25 as seen was developed in Central America to compensate low from the top of the coffee tree) positioned in the coffee market prices by promoting coffee agroforestry main producing zone of the canopy. From these systems to improve coffee farmers’ incomes through measurements at these three levels (U, upper; M, diversification (timber production), production and middle; L, low) in the canopy an average branch commercialisation of high-quality coffee and payment leaf area was computed, a total plant leaf area was of incentives for environmental services provided by estimated and leaf-to-fruit ratios were derived for each these ecologically sound coffee systems. Within this tree after counting the number of coffee berries. research framework, several scientific investigations To estimate light availability and temperature within have been undertaken to determine the importance the canopy, instantaneous measurements of PPFD and of factors such as microclimatic conditions, tree temperature were taken at leaf level in September 2000 productivity, berry position within the canopy, shade under clear sky conditions (ca 2000 µmol m2 s−1)using management and fertilisation regimes on coffee tree the quantum and temperature sensors of a DeltaT AP4 physiology and beverage quality. The present study porometer (DeltaT, Burwell, UK). Measurements focuses on the effects of tree productivity, manipulated were performed on the right leaf of leaf pairs 3, 6, 12, by fruit thinning, and light regime on the size and 15, 18, 21, 24 and 27 on the three selected branches, biochemical composition of coffee beans and their with leaf pair 3 being the closest to the tree trunk impact on beverage quality. inside the canopy and leaf pairs 18–27 the outermost ones. Values presented for each leaf position within a branch are means of the 16 spot readings, all taken MATERIALS AND METHODS between 10:00 and 12:00 (i.e. solar noon ±1h). Experimental location and design The study was carried out over three production Fruit parameters cycles, from March 1999 to February 2002, on Arabica Only fully ripe coffee berries, as determined by the coffee (C. arabica L.) trees of the dwarf cultivar ‘Costa bright red colour of their skin, were harvested from Rica 95’ planted under the optimal coffee-growing individual trees. Five to six harvests were necessary to conditions of the Coffee Research Centre (CICAFE), collect all the berries over a period of 3 months. The Heredia, Costa Rica at 1180 m elevation, with an fresh weight of berries was recorded at each harvest. annual average temperature of 20.5 ◦C, on an Andosol Coffee samples were prepared by the wet processing soil and with 2200 mm of annual rainfall. The plot was method (wet de-pulping, anaerobic fermentation for initiated in 1997 without shade. ‘Costa Rica 95’ has a 24 h, sun drying, de-husking) to obtain ready-to-be- maximum height, after four to five years, not exceeding roasted coffee beans (commonly named green coffee 2.5–3.0 m. Plant spacing was 2 m between rows and or green beans). For the production cycles of 1999 1 m within rows. Plants received 144 kg N, 24 kg P, and 2000, bean size was assessed for each tree and 80 kg K, 64 kg Mg and 4 kg B ha−1 annually, split into at each harvest with a series of sieves after sun drying two applications in May and August, and an additional beans to a water content of 120 g kg−1. The % of green application of 96 kg N ha−1 in early October. beans with larger sizes (bean diameter >6.75 mm) was In March 1999, four groups of 24 adjacent trees calculated. At each harvest, green beans of four trees were selected within the plot in adjacent rows; two per treatment were combined and a 50 g sample was groups of trees were maintained in full sun (sun) analysed for caffeine, trigonelline, chlorogenic acid, and the other two groups were shaded (shade) with fat and sucrose contents by near-infrared reflectance a net allowing the passage of only 55% of the spectrometry (NIRS) based on calibration curves photosynthetic photon flux density (PPFD). Within established for each compound.13 These compounds each group, three fruit loads (F, full initial fruit load; are considered important precursors for coffee aroma

198 J Sci Food Agric 86:197–204 (2006) Effects of productivity and shade on coffee quality and organoleptic properties of coffee beverage upon 1999 production, 6% for the second production and degradation during roasting through the Maillard 29% for the third production, resulting in a reduction reaction.14 These analyses were performed on an of 18% for the cumulative production over the three NIRS model 6500 spectrometer (NIRS System Inc., years. Fruit load also significantly affected coffee pro- Silver Spring, MD, USA) based on the reflectance of duction. In 1999, fruit thinning did not result in a ground (<0.5 mm) green coffee. The NIRS system was proportional decrease in production (Table 1). Coffee driven by NIRS2 (4.0) software (Intrasoft Int., Port production of trees with 1/4 load was only reduced by Matilda, PA, USA). Data of harvests were pooled per 50% in comparison with that of trees with full load. treatment for the purposes of this study. In the same manner, coffee production of trees with 1/2 load was only 25% lower than that of trees with Beverage quality assessment full load. In 2000, the trend was completely reversed: After eliminating most defective beans, 150 g samples trees with full load produced about 33% less coffee of green coffee were roasted for 7–8 min at 220 ◦Cin than trees with 1/2 load and about 50% less than a Probat BRZ2 laboratory roaster (Probat, Emmerich, trees with 1/4 load (Table 1). Cumulative production Germany). Cup quality tests were performed on of years 1999 and 2000, with imposed fruit thinning, an infusion prepared with 12 g of roasted and was not different for full and 1/2 loads. However, ground coffee. A panel of ten judges tasted three trees with 1/4 load produced 25% less coffee. Without cups of 120 mL of infusion for each sample. The any fruit thinning in 2001, coffee production was not four main beverage attributes (acidity, bitterness, significantly different between trees that had had dif- astringency and body) were estimated using scales ferent fruit loads during the previous two production ranging from 0 to 5, where 0 = null, 1 = very light, cycles (Table 1). Changes in productivity of trees with 2 = light, 3 = regular, 4 = strong and 5 = very strong. full load between the two production cycles (1999 and An additional preference score was also used: 0 = 2000) illustrated perfectly the alternate bearing pattern not good for drinking, 1 = bad, 2 = regular, 3 = good of coffee, as they produced the most during the first and 4 = very good. The tests were repeated three times year and the least during the second year. Interestingly, and values are means of three sessions. fruit thinning to a quarter of the production potential resulted in the most balanced production pattern, but Data analysis led to the highest productivity without fruit thinning Statistica software (version 5, Statsoft Inc., Tulsa, during the third year. Shade also reduced alternate OK, USA) was used to perform all statistical analyses. bearing (Table 1). The 2000 production was equiv- Data were analysed per year (only production for alent to 75% of the previous production (1999) and 2001) according to a factorial design with PPFD level 80% of the following one (2001) in shade conditions. (shade and sun) and fruit load (F, 1/2 and 1/4) as the In sun conditions, variation in productivity from one two factors. year to the next was much higher, as the 2000 production was equivalent to 69% of the previous production (1999) and only 60% of the 2001 production. RESULTS Effects of shade and fruit load on coffee Effects of fruit load and shade on light productivity and alternate bearing availability, leaf temperature and leaf-to-fruit Shade significantly decreased coffee production under ratio the optimal coffee-growing conditions of the site Shade considerably affected the microenvironment (Table 1). With fruit loads combined, coffee produc- in which fruits were developing. Shade had a very tion was 14% lower in shade than in full sun for the strong effect on light availability within the coffee

Table 1. Effects of PPFD regime (45% shade or full sun) and fruit load (full (F), half (1/2) or quarter (1/4) of initial fruit load) on coffee production, branch leaf area, individual leaf area, leaf-to-fruit ratio and % of beans with larger sizes

Yield (g berries Branch leaf Average leaf Leaf-to-fruit % of beans with per plant) area (cm2) area (cm2) ratio (cm2 per fruit) larger sizes

1999 2000 2001a 1999 2000 1999 2000 1999 2000 1999 2000

Shade 2340 1770 2220 730 590 36 42 18 18 63.5 72.1 Sun 2700 1880 3130 650 380 30 28 14 12 62.5 65.6 P 0.03 NS 0.001 0.001 0.001 0.001 0.001 0.05 0.001 NS 0.001 F 3463 928 2917 620 397 33 31 8 19 56.2 67.1 1/2 3210 1457 3074 730 549 34 38 11 17 61.7 70.7 1/4 1698 1889 3453 730 503 33 38 20 12 67.0 71.8 P 0.001 0.001 NS 0.05 0.05 NS NS 0.05 0.05 0.02 NS Pinteract NS NS NS 0.05 0.05 NS NS 0.05 0.05 NS NS a Without fruit thinning. NS, non-signiﬁcant (P > 0.05).

J Sci Food Agric 86:197–204 (2006) 199 P Vaast et al.

1600 fruit for sun versus 18 cm2 per fruit for shade in 1999 1400 A and a value of 12 cm2 perfruitforsunversus 18 cm2 )

-1 1200 s per fruit for shade in 2000. As expected, fruit thinning -2 1000 also resulted in strong alterations of the leaf-to-fruit 800 mol m

µ ratio. At the bean-ﬁlling stage in 1999, this ratio was 600 8cm2 per fruit for full load versus 11 and 20 cm2 for 400 PPFD ( 1/2 and 1/4 loads respectively. In 2000, owing to lower 200 production caused by alternate bearing, the trend was 0 36912 15 18 21 36912 15 18 21 24 36912 15 18 21 24 27 reversed and the leaf-to-fruit ratios were almost twice UM Las large for full and 1/2 loads compared with 1/4 load, Leaf position within branch with values of 19, 17 and 12 cm2 per fruit respectively. 1600 Incidentally, these higher leaf areas of shade trees also 1400 B explained the low light availability of shade trees in )

-1 1200 s comparison with sun trees as previously presented in -2 1000 Fig. 1. 800 mol m µ 600 400 PPFD ( 200 Effects of fruit load and shade on coffee berry 0 ripening 36912 15 18 21 3691215182124 36912 15 18 21 24 27 Shade and fruit load significantly affected the UM L berry-ripening process (Fig. 2). In a warmer micro- Leaf position within branch environment with high irradiance, coffee berries Figure 1. Measurements of PPFD levels at different leaf positions ripened faster in full sun than in shade. Therefore (from inner leaf position 3 close to tree trunk to outermost positions) the harvest peak was delayed by about 1 month owing on branches in upper (U), middle (M) and lower (L) parts of coffee to shade. During the first production cycle (1999) canopy of (A) sun-grown and (B) shade-grown trees at bean-filling stage during 2000 production cycle. and by the fourth harvest (19/01/2000), more than 85% of the coffee berries were already harvested in full sun compared with 65% in shade (Fig. 2). A canopy (Fig. 1). With the exception of the outermost clear trend could also be observed with fruit load: the − leaves, PPFD levels were below 200 µmol m 2 s−1 for lower the fruit load, the faster was the ripening of all leaves at all branch levels within the canopy of the coffee berries, irrespective of whether the coffee shade trees. In contrast, almost all leaves of sun trees plants were managed under sun or shade. By the − received PPFD levels well above 200 µmol m 2 s−1. third harvest (29/12/1999), 65% of the berries were Furthermore, leaves on the outer parts (leaf positions ripened at 1/4 load in full sun, whereas only 42% 12–18) of the upper and middle branches, where most were ready for harvest at full load. During the second of the coffee berries were produced, received PPFD production cycle (2000) the observations confirmed − levels above 500 µmol m 2 s−1. Leaf temperature the delaying effect of shade on coffee berry ripening, differences were also noticeable between shade and as 82% of berries were already harvested at the third ◦ sun trees. Differences of 4 C for inner leaves (up to harvest (07/01/2001) in full sun and only 60% in ◦ leaf 6) and 2 C for outer leaves were observed between shade (Fig. 2). The hastening effect of fruit load on shade and sun trees. berry ripening was not observed in 2000. This is due to Shade and fruit load considerably altered leaf-to- the fact that the overall productivity of trees was lower fruit ratios. Although coffee branch development is during this second cycle and therefore fruit thinning continuous and therefore leaf-to-fruit ratio evolves did not result in fruit load differences large enough to along the production cycle, the ratios presented here significantly affect coffee ripening as observed during (Table 1) are the ones registered at the peak of bean the previous production cycle. filling, the most critical time in terms of carbohydrate competition between developing vegetative parts and coffee berries. In 1999, shade increased the average Effects of fruit load and shade on coffee bean area of individual leaves, as values for shade and sun size leaves were 36 and 30 cm2 respectively. This trend Fruit load and shade had significant effects on was even more pronounced in 2000, with values of coffee bean size (Table 1). In 1999, it could clearly 42 and 28 cm2 for shade and sun leaves respectively. be observed that decreasing fruit load resulted in Furthermore, shade increased leaf lifespan by up to an increasing % of beans with larger sizes (bean 2 months (data not presented). This resulted in a diameter >6.75 mm). Owing to an overall lower tree higher average leaf area per branch, with a value of productivity caused by the alternate bearing pattern 650 cm2 for sun versus 730 cm2 for shade in 1999 and during the second year (2000), fruit thinning did a value of 380 cm2 for sun versus 590 cm2 for shade not result in fruit load differences large enough to in 2000. Consequently, leaf-to-fruit ratios were also significantly affect bean size. On the other hand, shade strongly affected by shade, with a value of 14 cm2 per enhanced bean size during this 2000 cycle.

200 J Sci Food Agric 86:197–204 (2006) Effects of productivity and shade on coffee quality

Harvests 1999 in Shade Harvests 1999 in Sun 24/02/00 10/02/00 19/01/00 24/02/00 10/02/00 19/01/00 29/12/99 05/12/99 22/11/99 29/12/99 05/12/99 22/11/99 100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0% F 1/2 1/4 F 1/2 1/4

Harvests 2000 in Shade Harvests 2000 in Sun 22/02/01 07/02/01 07/01/01 22/02/01 07/02/01 07/01/01 07/12/00 23/11/00 07/12/00 23/11/00 100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0% F 1/2 1/4 F 1/2 1/4

Figure 2. Effects of PPFD regime (45% shade or full sun) and fruit load (full (F), half (1/2) or quarter (1/4) of initial fruit load) on distribution of harvests during 1999 and 2000 production cycles.

Effects of shade, fruit load and year of Effects of shade, fruit load and year of production on coffee bean composition production on beverage quality In 1999, shade had significant effects on the Shade significantly affected beverage quality (Table 3). biochemical composition of coffee beans (Table 2). Negative attributes such as bitterness and astringency Caffeine and fat contents were higher in beans of were higher for coffee beverage prepared from sun- shade-grown plants, whereas sucrose, chlorogenic acid grown beans than for that prepared from shade-grown and trigonelline contents were higher in beans of sun- beans during the two consecutive production cycles. grown plants. In 2000, the same trends could be Furthermore, positive attributes such as beverage observed, but only significantly for caffeine, fat and acidity and preference were significantly higher for trigonelline. Fruit load had no significant effect on shade-grown beans. Fruit load had a significant effect coffee bean composition (Table 2). on beverage quality, with a trend indicating higher

Table 2. Effects of PPFD regime (45% shade or full sun), fruit load (full (F), half (1/2) or quarter (1/4) of initial fruit load) and year of production on coffee bean biochemical composition (g kg−1 bean dry weight)

Chlorogenic Caffeine Fat Sucrose acids Trigonelline

1999 2000 1999 2000 1999 2000 1999 2000 1999 2000

Shade 14.8 14.1 131 117 82 77.3 76.2 82.1 9.9 9.7 Sun 14.2 13.6 122 115 84 78.4 77.1 82.6 10.7 10.1 P 0.001 0.001 0.001 0.05 0.001 NS 0.001 NS 0.001 0.001 F 14.3 14.1 127 119 84 76.7 76.6 82.3 10.0 9.9 1/2 14.5 14.2 127 119 83 76.6 76.7 82.2 10.3 9.9 1/4 14.6 14.1 125 116 83 77.8 76.6 82.6 10.4 10.0 P 0.001 NS NS NS NS NS NS NS 0.01 NS Pinteract NS NS NS NS NS NS NS NS 0.007 NS

NS, non-signiﬁcant (P > 0.05).

J Sci Food Agric 86:197–204 (2006) 201 P Vaast et al.

Table 3. Effects of PPFD regime (45% shade or full sun), fruit load (full (F), half (1/2) or quarter (1/4) of initial fruit load) and year of production on beverage characteristics

Aciditya Bitternessa Astringencya Bodya Preferenceb

1999 2000 1999 2000 1999 2000 1999 2000 1999 2000

Shade 2.27 2.45 2.65 2.65 1.68 0.35 2.78 2.50 2.57 2.80 Sun 1.67 2.21 2.95 2.88 1.86 0.41 2.91 2.67 2.29 2.58 P 0.001 0.04 0.002 0.01 0.02 NS 0.05 0.05 0.01 0.02 F 1.91 2.47 2.86 2.83 1.82 0.46 2.92 2.66 2.42 2.76 1/2 2.02 2.41 2.75 2.73 1.80 0.36 2.89 2.53 2.64 2.70 1/4 2.13 2.27 2.75 2.75 1.79 0.34 2.72 2.66 2.73 2.74 P 0.03 0.05 NS NS NS NS 0.05 NS 0.001 NS Pinteract 0.09 NS NS NS NS NS NS NS 0.001 NS a The scores for acidity, bitterness, astringency and body were based on a scale of 0–5, where 0 = null, 1 = very light, 2 = light, 3 = regular, 4 = strong and 5 = very strong. b Overall preference was based on a scale of 0–4, where 0 = not good for drinking, 1 = bad, 2 = regular, 3 = good and 4 = very good. Each value is the average score of ten judges during three tasting sessions. NS, non-significant (P > 0.05). preference with decreasing fruit load, especially in coffee berries under shade and sun conditions. Many 1999 (Table 3). Interestingly, the overall beverage authors18– 24 have highlighted the strong effect of light quality (higher acidity, lower astringency and higher exposure of the fruit on its maturation, particularly its preference) was higher in 2000, when production was skin colour and flesh ripening. Although Montavon around 30% lower (Table 1), than in 1999 (Table 3). et al.25 have recently emphasised the fact that berry maturation clearly favours the development of high- quality flavour in the coffee brew, bean maturation is DISCUSSION certainly more critical than that of its surrounding 26 The results of this study show the importance of light flesh for coffee as for other nut trees. Adelay regime on coffee productivity and bearing pattern. In in ripening between the berry pulp and the bean 27 the optimal ecological conditions for coffee growing of has already been documented and proposed as the present study (the central valley of Costa Rica is one of the reasons explaining observed differences in one of the world’s coffee-producing regions with the beverage quality between shade-grown and sun-grown 11 highest commercial productivity, with up to 3000 kg coffee. In the present study, caffeine and fat contents coffee beans ha−1 year−1), a rather dense shade level were highest in beans of shade-grown plants, whereas of 45% reduced by only 18% the productivity of sucrose, chlorogenic acid and trigonelline contents trees over three consecutive production cycles. These were highest in beans of sun-grown plants. A similar results confirm previous studies showing that artificial negative relationship between fat and sucrose contents shade12,15,16 or shade trees9 reduce coffee fruit load has been reported for C. canephora28 and C. arabica29 through their effects on coffee physiology, such as coffee beans. Sucrose is a precursor of polysaccharides longer internodes, fewer fruiting nodes and lower and fat compounds in coffee beans.30 Therefore a flower induction. In sun conditions, biannual variation high sucrose content coupled with a low fat content in in productivity was much higher than under shade beans of sun-grown coffee could very well indicate that owing to the fact that sun-grown trees had higher fruit bean filling and fat synthesis were not fully achieved. loads and that coffee trees prioritized the allocation Higher chlorogenic acid and trigonelline contents of carbohydrates to berries at the detriment of in beans produced by sun-grown plants could also young vegetative branch parts, thus conditioning the point towards incomplete bean maturation and explain production level of the following year.4,5 Therefore the the higher bitterness and astringency of the coffee present results support the idea that shade decreases beverage. To decrease the number of hand pickings or the magnitude of the alternate bearing of coffee trees to allow mechanical harvesting, experimental spraying as often hypothesised in the literature.5,9,12 This is with ethylene-based products to group maturation particularly important for individual coffee growers of coffee berries has resulted in lower beverage or cooperatives, as it limits the need to invest in quality.31,32 This was attributed to the fact that processing facilities that are oversized every other year coffee berry flesh maturation was artificially hastened, and allows them to market a more constant volume whereas that of the bean was not. The present results and quality of coffee to buyers. demonstrate the beneficial synchronising effect of The present results confirmed the importance of shade through a decrease by half in the light intensity light regime regarding bean biochemical composition and by several degrees (up to 4 ◦C) in the temperature and quality of the coffee beverage.11,12,17 For the first around the berries, which slows down the ripening time they documented the large differences in light process of coffee berry flesh and allows more time exposure and air temperature that are experienced by for complete bean filling. This indicates that this

202 J Sci Food Agric 86:197–204 (2006) Effects of productivity and shade on coffee quality buffering effect of shade mimics that of increasing research was mostly focused on enhancing productivity altitude, as it is generally accepted in the tropics rather than coffee quality, tree longevity and plantation that each increase of 100 m in altitude decreases sustainability. Nonetheless, alternative techniques do the average daily temperature by 1 ◦C. Therefore exist. Through its effect on decreasing flower intensity, shade management can partially compensate the shade management is certainly a management practice altitude deficit of many low-altitude coffee-producing worth promoting to coffee farmers in order to zones of Central America and should permit coffee overcome the inability of dwarf coffee cultivars to production of good quality. Nowadays, time of harvest regulate their productivity. Selective pruning of heavy- is guesstimated on the basis of the number of weeks bearing branches is also a management technique that after flowering and accumulated experience of local deserves more attention. Recent works on the breeding conditions by coffee growers. It would be particularly of dwarf cultivars with traditional ones also appear to worth undertaking an investigation on the sum of be promising, as hybrids are more vigorous and exhibit degree days as an indicator of coffee bean maturation, lower biannual bearing patterns.29 In any case, these as commonly used for many other fruit trees. results highlight the need for further investigation The present results illustrate the antagonistic on carbohydrate production and allocation between relationships between coffee tree productivity and fruit vegetative and reproductive parts in different regions size and quality as already documented for many other of the coffee canopy to refine the existing model fruit tree species.18,33– 35 Cannell5 has already pointed predicting fruit growth at the coffee branch level,4 out the competition for carbohydrates among coffee extend its applicability to the whole plant level and berries during heavy production cycles and its negative explore new management practices. impact on bean size and beverage quality. The present results confirm this competitive effect among coffee CONCLUSION berries regarding bean size and beverage quality in It appears clearly that in full sun the dwarf coffee view of the effects of fruit thinning, shade and year of cultivar ‘Costa Rica 95’ poorly self-regulates its production. In 1999, the year of the highest overall productivity, produces beans of lower quality and tree productivity, decreasing fruit load resulted in a experiences stronger alternate bearing than in shade. larger bean size and higher coffee quality. Irrespective As dwarf cultivars (caturra, catuai and catimors) are of the light regime, trees produced coffee of higher now predominant in coffee plantations of Central quality in 2000 when the overall tree productivity was America, this greatly advocates for the promotion 30% lower than during the previous year. Through its of agricultural practices that improve plantation effects on limiting flowering intensity and hence tree sustainability and coffee quality to secure higher productivity, shade management consistently resulted revenues to farmers in the long term. Indeed, the in higher beverage quality over the two consecutive present differences due to shade and fruit load are production cycles. important enough to have economic significance for These results demonstrate that fruit thinning coffee farmers, since the premium paid for high enhanced bean size and hastened the maturation coffee quality can amount to more than 100% of process. Palmer et al.36 have also shown for apple trees the market price of standard coffee quality. Although that lighter crop loads resulted in earlier fruit maturity the present observations need to be confirmed under and enhanced quality compared with heavy crop loads. different producing conditions, they should result in In the present experiment the shorter duration of recommendations in terms of coffee management. the bean-filling period was counterbalanced by an Certainly, agricultural practices (particularly shade ample carbohydrate supply to growing fruits due to management and pruning) limiting fruit load, lowering high leaf-to-fruit ratios in their vicinity. As leaf-to- tree stress, better balancing leaf-to-fruit ratios and fruit ratios varied greatly within the coffee canopy, favouring slow ripening of coffee berry pulp and more investigation is under way to test the effect of adequate bean filling should help produce coffee of coffee berry position and yield distribution on bean higher quality and larger bean size. Bean size is characteristics and beverage quality. Fruit thinning particularly important, as it is often the main criterion is a common practice to improve fruit growth and along with bean colour and % of physical defects quality for many fruit trees such as peach, kiwi on which the exportability of coffee in producing 18,35– 37 and apple. However, this management practice countries is based. Since coffee unfit for export and (via chemical spraying or manual thinning) is rarely consumed locally is often sold at less than half the implemented by coffee growers worldwide despite the international market price in Central America, there fact that it has been long documented that coffee trees is considerable economic interest in producing the experience a biannual bearing pattern and overbearing highest proportion possible of exportable beans of branch die-back due to competition for carbohydrates large size. between coffee berries and developing young branch parts, thus conditioning the production level of the following year.5 This is due to the fact that neither ACKNOWLEDGEMENTS chemical spraying nor manual thinning has been The authors thank ICAFE (Coffee Institute of intensively studied in the case of coffee, because past Costa Rica) for maintenance of the experimental

J Sci Food Agric 86:197–204 (2006) 203 P Vaast et al. plot and usage of their processing facilities; Fabrice 18 Corelli-Grappadelli L and Coston DC, Thinning pattern and Davrieux, a researcher at the CIRAD laboratory of light environment in peach tree canopies influence fruit coffee technology, for the NIRS analyses; and the quality. Hort Sci 26:1464–1466 (1991). 19 Barritt BH, Rom CR, Konishi BJ and Dilley MA, Light level European Commission (INCO-DEV project CASCA influences spur quality and canopy development and light ICA4-CT-2001-10071) and the Science and Cultural interception influences fruit production in apple. Hort Sci Cooperation Centre, French Embassy, Costa Rica 26:993–999 (1991). for supporting part of the operational costs of this 20 Dann IR and Jerie PH, Gradients in maturity and sugar levels research. of fruit within peach trees. 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