Agro-morphological response of cocoa tree (Theobroma cacao L) hybrid families to water deficit in Côte d'Ivoire

 Corresponding author: Tchrewa Stanislas KOUAME Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Agro-morphological response of cocoa tree (Theobroma cacao L) hybrid families to water deficit in Côte d’Ivoire Tchrewa Stanislas KOUAME 1, 2, *, Sahin Brigitte GUIRAUD 2, Diane Estelle GNAPI 3, Inago Caudou TREBISSOU 1, Yves Mathurin ATCHI 1, 4, Firmin Vanié Gouré Bi 1, 2, Attiapo Pépin ASSI 1, 2, Okayo Sandrine MINAKOU 1, 2, Gnion Mathias TAHI 5 and Doffou Sélastique AKAFFOU 2 1 National Center for Agronomic Research (CNRA), Divo Research Station and Genetics Laboratory, BP 808, Divo, Côte d'Ivoire. 2 Jean Lorougnon Guédé University, UFR Agroforestry, Laboratory of Agricultural Production Improvement, Research and Training Unit in Agroforestry, BP 150, Daloa, Côte d'Ivoire. 3 National Center for Agronomic Research (CNRA), Cotton Research Station, BP 633 Bouaké, Côte d'Ivoire. 4 Félix Houphouët-Boigny University of Abidjan, UFR Biosciences, Genetics Laboratory, BP 582, Abidjan 22, Côte d’Ivoire. 5 Coffee-Cocoa Council, Directorate of Research and Climate Change Management, BP 808, Divo, Côte d’Ivoire. World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 Publication history: Received on 19 September 2025; revised on 26 October 2025; accepted on 29 October 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.28.1.3672 Abstract Drought caused by climate change is triggered by deforestation. It has altered rainfall distribution, humidity, and air temperature. This situation threatens the sustainability of cocoa cultivation in certain regions where rainfall is between 900 and 1,200 mm. A study was conducted in a zone with insufficient rainfall (Toumodi) and a zone with normal rainfall (Divo). The objective of this study was to determine the impact of drought on 25 hybrid families through agromorphological parameters. The experimental design was a factorial block including region and family as factors. Drought caused an increase in mortality and a reduction in growth and development of the hybrid families, as well as a decline in production in the Toumodi area. Across the two agro-ecological zones, eleven (11) out of the twenty-five (25) hybrid families (F23, F22, F7, F19, F18, F25, F15, F1, F16, F24, and F13) exhibited the best agro-morphological performance. Moreover, in the drought-affected area of Toumodi, five (05) other hybrid families (F4, F12, F14, F10, and F21) showed superior performance for the evaluated parameters. These hybrid families are potentially resistant to water deficit associated with drought. Keywords: Evaluation; Cocoa Tree; Agro-Morphological Parameters; Climate Change 1. Introduction The cocoa tree (Theobroma cacao L.) is a perennial plant belonging to the family Malvaceae. It is cultivated for its beans, which are the raw material for chocolate production [10]. West Africa accounts for approximately 74% of the global cocoa production, estimated at about 4.5 million tons of marketable cocoa [14]. Côte d’Ivoire is the world’s leading cocoa producer, with an annual output estimated at 1.8 million tons of marketable cocoa [14]. This production contributes 15% to the national GDP and represents about 40% of export revenues [14]. Despite these impressive performances, Ivorian cocoa production is currently facing several constraints, including: the aging of orchards [3; 18] the low level of use of improved plant material [18;27], high pest pressure [16; 17; 19; 21] drought. Over the past few decades, cocoa-producing areas in Côte d'Ivoire have been marked by high climate variability [8 ;11 ;15]. This climate variability has led to a drop in rainfall below threshold values (1,200 mm) [8], thereby World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2104 increasing the number of dry months per year (from 3 to 6 months). The water deficit not only affects the survival of cocoa trees, but also their vegetative growth and physiological development [23]. To address this issue, the National Center for Agronomic Research (CNRA) has developed high-yielding cocoa varieties that combine good technological qualities with resistance to pathogens under optimal growing conditions. However, with the advent of climate change, it has become necessary to study the performance of these varieties under waterdeficit conditions. In this context, the present study aims to evaluate the impact of drought on the agro-morphological performance of 25 hybrid families of cocoa (Theobroma cacao L.) planted in Divo (normal rainfall zone) and Toumodi (low rainfall zone). 2. Material and methods 2.1. Study area The study was conducted on two experimental plots, one located in Toumodi (a low-rainfall zone at 6°55’ N latitude and 5°03’ W longitude) and the other in Divo (a normal-rainfall zone at 5°48’ N latitude and 5°18’ W longitude). Table 1 presents the climatic characteristics (rainfall and temperature) of the two study zones. Table 1 Rainfull and temperatures in the areas where the study sites are located Rainfull (mm) Temperature (°C) Minimum Maximum Average Minimum Maximum Average Divo 24 249 1469 24,5 27,6 26,2 Toumodi 12 180 1091 25,5 28,4 26,591 2.2. Study area The plant material consists of twenty-five (25) hybrid families obtained through controlled hybridization (Table 2). Twenty-seven (27) plants were evaluated per hybrid family. A total of 1,450 genotypes spread over two (02) plots in two (02) areas with different rainfall patterns were monitored. These plants were planted for testing in June 2013. Table 2 Hybrid families resulting from crosses between parents Manual hybridization Hybrid family codes Females Males UPA402 X UF676 F1 UPA409 X IFC1 F2 UPA608 X IFC412 F3 UPA413 X IFC1 F4 UPA603 X UF667 F5 UPA409 X POR F6 T85/799 X IFC15 F7 SCA6 X ICS1 F8 PA150 X IFC5 F9 T79/501 X IFC5 F10 IFC720 X ICS46 F11 IMC67 X IFC1 F12 World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2105 MOQ413 X SCA6 F13 POR X T60/887 F14 PA150 X POR F15 IFC303 X IFC1 F16 SCA6 X LAF1 F17 IFC29 X IFC303 F18 T60/887 X IMC67 F19 PA150 X T60/887 F20 P7 X GU175A F21 P7 X GU284 A F22 IFC303 X GU175A F23 IFC303 X GU284 A F24 P7 X IMC67 F25 3. Methodology 3.1. Experimental The experimentation consisted of a Fisher block for each zone. Treatments were applied to the twenty-five (25) hybrid families, with three (03) replications of nine (09) trees each, totaling twenty-seven (27) trees per hybrid family in the Divo zone, and three (03) replications of seven (07) trees, totaling twenty-one (21) trees per hybrid family in the Toumodi zone. The standard planting density of 1,333 trees per hectare (3 m between rows and 2.5 m between trees) was maintained. Considering both zones and hybrid families together, the study was conducted as a two-factor trial (zone*family). In total, 4,092 trees (genotypes) were evaluated. 3.2. Evaluated Parameters Two types of parameters were evaluated: (1) the mortality rate and (2) growth and development parameters. 3.3. Mortality Rate The mortality rate was assessed nine (09) years after field planting. It was expressed as a percentage and calculated as the ratio of the number of dead trees to the total number of trees planted. 3.4. Growth and Development Parameters These included the collar diameter at 30 cm above the ground, tree cross-sectional area, and leaf dimensions. The collar diameter was measured at 30 cm above the ground using a caliper. The tree circumference was measured at 1.5 m above the ground, and the cross-sectional area was calculated using the following formula: (𝒄𝒎𝟐)=(𝑪𝒊𝒓)𝟐 𝟒𝝅 Leaf dimensions (length and width) were measured using a graduated ruler on three (03) leaves per tree, and the individual leaf area was calculated following the formula of [26]: 𝑺 (𝒄𝒎𝟐) = 𝛑 𝐚𝐛 𝟒 Where a=A/2 and b=B/2; A= leaf length, B = leaf width. The total leaf zone was calculated by summing the individual leaf zone World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2106 3.5. Statistical data analysis To identify the sources of variation within hybrid families and between zones, one-way (ANOVA) and two-way (MANOVA) analyses of variance were performed. The Newman-Keuls test at a significance level of α = 5% was used to determine the existence of homogeneous groups among hybrid families and between zones. For each analyzed variable, this test allowed comparison of the mean values of hybrid families within each zone. Subsequently, principal component analysis (PCA) was conducted based on the mean values obtained from the variance analysis, aiming to establish correlations between parameters and the principal axes. Finally, hierarchical cluster analysis (HCA) was performed to structure homogeneous groups around discriminant variables. All analyses were conducted using SAS 9.4 (SAS Institute, 2018), XLSTAT version 2014, and R version 4.1.2. 4. Results 4.1. Effects of zones on cocoa tree mortality, growth and development The zones exhibited significant differences for all evaluated parameters across all hybrid families. The zone * family interactions were significant for the mortality rate (p = 0.0014), collar diameter at 30 cm above the ground (p = 0.0241), cross-sectional area at 1.5 m above the ground (p = 0.0017), and total leaf area (p = 0.01876) (Table 3). The mortality rate of cocoa trees, nine (09) years after field planting, varied highly significantly according to the agroclimatic zones. It averaged 6.15% in the Divo zone, which recorded the lowest mean among all 25 families, compared to 42.29% in the Toumodi zone, which exhibited the highest rate. The largest collar diameters at 30 cm above the ground were obtained in the Divo zone (13.81 cm), whereas the smallest diameters were recorded in the Toumodi zone (12.49 cm). Regarding tree height, the Divo zone showed the highest average value (5.60 m), while the Toumodi zone had the lowest (4.14 m). For cross-sectional area, Divo presented the largest mean (109.96 cm²), and Toumodi the smallest (87.55 cm²). For total leaf area, the Divo zone exhibited the highest values with a mean of 201.57 cm², whereas the Toumodi zone showed the lowest values (198.38 cm²). Table 3 Comparison of study zones based on mortality rate and growth and development parameters of cocoa trees Growth and development parameters Zones Mortality Rate (%) Collar diameter at 30 cm Above Ground (cm) Cross-Sectional Area at 1.5 m Above Ground (cm2) Total Leaf Area (cm2) Divo 6.15± 0.00b 13.81±2,71a 109.96±52.68a 201.57±67.72a Toumodi 42.29±0.03a 12.49±3.58b 87.55±51.90b 198.38±73.41b Mean 24.22 13.37 102.58 200.52 CV (%) 15.45 21.92 49.68 26.7 P-value < 0.05 <.0001 <.0001 <.0001 <.0001 Zone*family 0.014 0.0241 0.0017 0.01876 In each column, means followed by the same letter are not significantly different at the 5% significance level 4.2. Influence of Zones on the Growth and Development Parameters of Cocoa Trees Since the zone*family interaction was significant for all evaluated parameters, the ranking of families was performed separately by zone (Table 4). The mortality rate showed uniformity in the Divo zone and significant differences among hybrid families in the Toumodi zone. The highest mortality rate was observed in family F6 (81%) in the Toumodi zone, while the lowest rates were recorded in families F21 and F24 (16.71%). Collar diameter at 30 cm above the ground showed significant differences among hybrid families in the Divo zone and uniformity in the Toumodi zone. The largest diameter was recorded in family F10 (15.76 cm) in Divo, whereas the smallest diameters were observed in families F7 (13.53 cm) and F17 (13.33 cm) in Divo. Cross-sectional area exhibited significant differences among hybrid families across all zones. The largest cross-sectional areas were recorded in family F21 (157 cm²) in Divo and F14 (128.57 cm²) in Toumodi, while the smallest areas were observed in families F23 (80.69 cm²) in Divo and F3 (55.81 cm²) in Toumodi. Total leaf area also showed significant differences among hybrid families in all zones. The largest leaf areas were obtained by family F13 (245.4 cm²) in Divo and families F1 (218.47 cm²) and F22 (215.02 cm²) in Toumodi. Conversely, the smallest total leaf areas were observed in families F3 (155.39 cm²) and F8 (154.95 cm²) in Divo, and F2 (134.35 cm²) in Toumodi. World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2107 Table 4 Comparison of hybrid families based on mortality rate, growth, and development parameters across different zones Mortality Rate (%) Collar diameter at 30 cm Above Ground (cm) Cross-Sectional Area at 1.5 m Above Ground (cm2) Total Leaf Area (cm2) Famill e Divo Toumodi Divo Toumodi Divo Toumodi Divo Toumodi F1 6.18±0.03a 66.33±0.04bdac 13.52±0.48ba 12.84±2.07a 95.63±10.5bc 62.35±13.2bc 215.74±9.34bdac 218.74±18.3a F10 5.63±0.02a 28.33±0.14egf 15.67±0.31a 14.56±0.73a 114.88±8.4bac 114.92±13.8ba 187.65±9.4fdehcg 166.39±8.6ba F11 8.37±0.02a 52.33±0.12ebdacf 14.49±0.61ba 12.63±0.74a 117.53±11bac 106.81±15.1ba 224.22±11.38ba 151.94±16.4ba F12 10.18±0.07a 34.52±0.15edgf 14.63±0.5ba 11.58±1.25a 124.81±11.08bac 66.62±10.2bc 193.67±8.85fbdecg 173.55±10.7ba F13 2.89±0.01a 43±0.08ebdgcf 14.21±0.51ba 11.48±0.98a 100.18±10.21bc 80.11±11.2bac 245.4±12.17a 195.98±18.5ba F14 5.63±0.02a 33.33±0.09edgf 13.12±0.58ba 14.36±0.71a 110.43±11.6bc 128.57±16.8a 182.57±10.08fdehg 176.44±9.6ba F15 5.63±0.02a 25.19±0.11egf 13.45±0.45ba 11.9±0.87a 129.73±11.34bac 76.11±9.2bac 221.11± 12.22bac 193.75±10.3ba F16 5.63±0.02a 29.52±0.20egf 13.68±0.47ba 11.86±0.88a 107.83±6.82bc 81.97±13.2bac 217.76±25.62bdac 164.61±8.3ba F17 6.18±0.03a 71.67±0.14bac 13.33±0.59ba 14.32±1.49a 120.19±10.42bac 84.96±34.1bac 165.24±8.53hg 158.46±13.3ba F18 8.93±0.03a 28.67±0.08egf 13.26±0.5ba 11.99±1.24a 102.68±11.65bc 74.32±16.8bac 201.7±12.25fbdec 180.48±17.5ba F19 2.89±0.0a 38.33±0.09edgcf 13.91±0.62ba 12.29±0.98a 104.87±11bc 89.46±17.6bac 202.53±10.15fbdec 204.96±11.4ba F2 5.63±0.02a 47.67±0.04ebdagcf 12.54±0.38b 11.57±1.05a 94.32±8.88bc 68.39±14.1bc 168.73±11.2fhg 134.35±17.2b F20 6.18±0.03a 66.67±0.12bdac 13.72±0.68ba 9.36 ±1.39a 112.3±13.84bc 60.73±15.5bc 186.44±11.2fdehcg 186.86±11.1ba F21 2.89±0.00a 16.71±0.13g 15.17±0.49ba 13.33±0.89a 157.53±11.32a 86.55±9.5bac 207.32±11.68bdec 200.83±12.2ba F22 2.89±0.00a 25.19±0.11egf 13.44±0.59ba 12.73±1.05a 125.14±13.46bac 85.76±10.2bac 203.36±14.48fbdec 215.02±9.5a F23 6.18±0.03a 20.19±0.11gf 12.43±0.37b 13.71±0.78a 80.69±7.36c 113.96±14.3ba 214.17±7.72bdac 199.97±9.1ba F24 9.3±0.06a 16.71±0.13g 12.93±0.5ba 13.14±0.72a 100.36±9.92bc 99.31±10.4ba 216.05±12.36bdac 186.9±9.2ba F25 2.89±0.00a 20.52±0.08gf 14.03±0.54ba 13.14±1.05a 110.82±7.74bc 108.31±15.3ba 219.07±13.13bac 166± 8.4ba F3 2.89±0.00a 76±0.05ba 13.33±0.36ba 9.92±1.76a 100.29±8.75bc 55.81±17.1c 155.39±9.09h 166.91±20.4ba F4 2.89±0.00a 24.86±0.16egf 13.99±0.45ba 11.93±0.51a 106.12±7.83bc 78.6±8.2bac 174.59±9.49fehg 188.14±9.6ba F5 6.18±0.03a 52.33±0.12ebdacf 13.69±0.67ba 10.69±0.95a 101.94±10.55bc 63.84±13.1bc 193.81±9.06fbdecg 177.51±7.9ba World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2108 F6 16.26±0.08a 81±0.05a 14.6±0.58ba 12.9±1.55a 98.6±9.7bc 86.27±17.2bac 187.98±12.9fbdehcg 159.85±14.3ba F7 2.89±0.00a 29.86±0.15egf 13.53±0.51ba 12.13±0.77a 86.21±8.05bc 83.63±13.1bac 198.23±13.3fbdecg 165.84±12.2ba F8 2.89±0.00a 57±0.14ebdac 14.13±0.59ba 12.38±0.79a 138.39±11.3ba 88.15±20.3bac 154.95±8.1h 162.59±12.2ba F9 15.71±0.06a 71.33±0.08bac 14.54±0.71ba 11.66±1.16a 103.95±9.21bc 68.17±16.2bc 218.34±12.7bdac 182.15±13.1ba Mean 6.15 42.29 13.8 12.48 109.96 87.55 201.566 181.18 CV (%) 9.96 48.96 19.27 28.349 46.427 31.15 29.557 24.24 P<0.05 0.4214 0.0007 0.0029 0.1865 <.0001 0.037 <.0001 0.0003 In each column, means followed by the same letter are not significantly different at the 5% significance level World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2109 4.3. Structuring of Hybrid Families Based on Mortality and Growth and Development Parameters In the Divo zone, the two principal axes from the principal component analysis (PCA) of hybrid families explained 72.17% of the observed variability. Axis 1 accounted for 42.53% of the total variability and was primarily defined by mortality rate and collar diameter at 30 cm above the ground, with squared cosines ranging from 0.485 to 0.723. Axis 2 explained 29.29% of the variability and was mainly associated with total leaf area (squared cosine = 0.654) (Figure 1A). Hierarchical cluster analysis (HCA) (Figure 1B) identified three groups of cocoa trees based on growth and development parameters. The first group, comprising families F2, F14, F20, F17, F4, F3, and F8, was characterized by low values for total leaf area, mortality rate, and collar diameter. The second group included families F23, F22, F7, F19, F5, F18, F25, F15, F1, F16, F24, and F13 and exhibited high total leaf area, low mortality rates, and intermediate collar diameter. The third group, consisting of families F11, F21, F12, F9, and F6, showed high values for total leaf area, collar diameter, and mortality rate. In the Toumodi zone, PCA explained 81.13% of the observed variability. Axis 1 accounted for 48.58% and was defined by total leaf area and collar diameter at 30 cm above the ground (squared cosines = 0.586 and 0.578, respectively). Axis 2 explained 32.55% of the variability and was primarily associated with mortality rate (squared cosine = 0.512) (Figure 2). HCA in Toumodi also revealed three groups. The first group, composed of families F3, F20, F5, and F9, was characterized by high mortality rates and low total leaf area and collar diameter. The second group, including families F8, F11, F17, F2, and F6, displayed high collar diameter and moderate total leaf area but moderate mortality rates. The third group, consisting of families F1, F13, F19, F15, F4, F18, F12, F16, F7, F25, F14, F10, F22, F24, F21, and F23, was characterized by high total leaf area and collar diameter and low mortality rates. Figure 1 Structuring of Hybrid Families into Homogeneous Groups Based on Vigor Variables and Mortality Rate Evaluated in the Field in the Divo Zone World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2110 Figure 2 Structuring of Hybrid Families into Homogeneous Groups Based on Vigor Variables and Mortality Rate Evaluated in the Field in the Toumodi Zone 5. Discussion The study conducted on twenty-five (25) cocoa hybrid families across two zones with different rainfall regimes demonstrated the depressive effect of drought on growth and development parameters, including trunk diameter, trunk cross-sectional area, and total leaf area. However, the mortality rate increased proportionally with the severity of the drought. The effect of drought altered the visual appearance of cocoa trees in the Toumodi zone, which experiences low rainfall, compared to those in the Divo zone. Cocoa leaves exhibited folding of the lamina around the central vein. Simultaneously, leaf color changed from deep green to light green, with yellowing patches appearing from the apical tip and spreading inward. This phenomenon marks the onset of water deficit. As the duration of drought increased, necrotic areas spread across the leaf lamina, which appeared less turgid, followed by progressive desiccation of the cocoa plants from the apex toward the roots, ultimately causing tree death. Hybrid families F21, F24, F23, F25, F4, F22, and F15 showed the lowest mortality rates. These findings are consistent with those of [9]and [24], who reported that leaf growth and development are strongly disrupted under limited water conditions. Plants subjected to severe water deficit due to drought generally exhibit accelerated leaf senescence, and excessive water loss can lead to cell death and, consequently, the death of the entire tree [22; 5]. The growth and development parameters (trunk diameter, trunk cross-sectional area, and leaf area) of cocoa genotypes decreased according to the severity of drought in the Toumodi zone. Hybrid families F14, F17, and F24 were less affected in collar diameter growth at 30 cm above the ground compared to their controls in the Divo zone, while families F14, F23, F25, and F24 showed higher trunk cross-sectional area relative to other hybrids in the same zone. This enhanced capacity for diameter and cross-sectional growth may be attributed to the hybrid vigor (heterozygosity) of these families under water stress conditions. These findings are consistent with Boyer [6; 7; 26; 21] , who demonstrated that vegetative growth parameters such as diameter and cross-sectional area can be used to discriminate varieties subjected to drought-induced water stress. The depressive effect of drought was also observed on total leaf area in the Toumodi zone. However, only hybrid families F22, F1, F19, and F21 produced the largest leaf areas. This high variability among hybrid families for total leaf area confirms the sensitivity of cocoa trees to minor fluctuations in soil moisture. According to [25], one of the first plant responses to water deficit is the reduction of leaf area and the number of functional leaves. Our results also corroborate those of [12; 4; 1; 2; 21], who reported that vegetative development under limited water availability in the field is World Journal of Advanced Research and Reviews, 2025, 28(01), 2103-2112 2111 strongly disrupted, primarily due to a significant decrease in the number of functional leaves and leaf area. This reduction in vegetative growth represents a plant response to dehydration, aimed at conserving water resources and ensuring survival [25; 21]. Leaves of plants subjected to water deficit typically reach smaller final sizes than those of control plants [13], with denser venation and enhanced peripheral protections, including a thicker cuticle and increased leaf pubescence. 6. Conclusion The objective of this study was to evaluate the agromorphological parameters of 25 cocoa hybrid families (Theobroma cacao L.) planted in two zones with different rainfall regimes. The results provided insights into how the cultivation zone can impact the agromorphological performance of these hybrid families. The findings revealed substantial genetic variability for vigor, growth, and development parameters in both the Divo and Toumodi zones. In the Divo zone, families F23, F22, F7, F19, F5, F18, F25, F15, F1, F16, F24, and F13 were characterized by large collar diameters at 30 cm above the ground, large trunk cross-sectional areas, and large total leaf areas. In the Toumodi zone, families F1, F13, F19, F15, F4, F18, F12, F16, F7, F25, F14, F10, F22, F24, F21, and F23 stood out for collar diameter, trunk cross-sectional area, and total leaf area. Across the two agroecological zones, eleven (11) hybrid families (F23, F22, F7, F19, F18, F25, F15, F1, F16, F24, and F13) demonstrated the best overall agromorphological performance among the 25 families. In the drought-prone Toumodi zone, five (5) additional hybrid families (F4, F12, F14, F10, and F21) exhibited superior performance for the evaluated parameters. Compliance with ethical standards Disclosure of conflict of interest The authors declared no conflict of interest Statement of informed consent All contributing authors read and approved the final manuscript for publication. References [1] Adra M (2010). Caractères physiologiques et biochimiques de tolérance du blé dur (Triticum durum Desf.) au stress hydrique. Thèse de doctorat. Univ. Mentouri. Constantine: 118 p. [2] Apshara SE, Rajesh MK, Balasimha D (2013). Assessment of morphological, physiological and molecular characteristics of cocoa accessions from central and South America in relation to drought tolerance. 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