Practical yield loss models for infestation of cocoa with cocoa pod borer moth,Conopomorpha cramerella (Snellen)

The cocoa pod borer, Conopomorpha cramerella (Snellen) (Gracillariidae: Gracillariinae), is an important pest of cocoa in Southeast Asia and Oceania, with devastating effects on yields. Using data on cocoa pod borer (CPB) infestation and cocoa yield from mixed-variety plantations in South Sulawesi, Indonesia, we developed models for estimating yield and yield loss under CPB attack. For six yield variables, two types of models were constructed: non-linear regressions based upon the presence or absence of infestation of pods (PI model), and multiple linear regressions for a four-point graded system of infestation severity (IS model). The IS models performed markedly better than PI models, in terms of percentage of variance explained, for all variables, also supported by Corrected Akaike Information Criterion values. But the explanatory power of the best-fit models was still poor for some variables. The fits were strongest for arguably the two most important variables in the industry, dry weight/pod and pod value (the number of pods required to achieve 1 kg of dry cocoa), with 62% and 69% of the variance accounted for, respectively. Validation of the dry weight/pod and pod value models against an independent dataset from South Sulawesi indicated that the models slightly under-estimated both yield indicators that increase concomitantly with the degree of yield loss. We propose the IS models, particularly that for pod value, as useful tools for industry, and argue that they will have broad utility given that they are based on mixed-cultivar plantations. Not only are these the first CPB yield-loss models to be based on commercial mixed plantings, they also represent the first attempt to employ a gradation of infestation severity based on simple visual assessment, which proved to be an important advance.     

The Effect of Liming on the Availability of Cadmium in Soils and Its Uptake in Cacao (Theobroma c acao L.) In Trinidad & Tobago

ABSTRACT

Cadmium (Cd) is absorbed and bio-accumulated by cacao (Theobroma cacao L.) trees, resulting in unacceptably elevated levels in cocoa beans, necessitating measures to reduce its uptake from soils. A field experiment, lasting 18 months, was carried out to assess the effectiveness of liming on pH, bioavailability of Cd in soils and its uptake in cacao tissues. The treatments were: (a) control (untreated) and (b) lime-treated trees. Results demonstrated a significant (P < 0.05) increase in the soil pH (lime treated) and a natural fluctuation in pH for the control. For the lime-treated trees, bioavailable Cd levels generally stabilized with no significant change (P > 0.05) compared to the significant (P < 0.05) increase showed by control trees. The Cd levels in the leaves of both treatments decreased, however, the rate of decline in leaf Cd concentrations for lime-treated trees (?0.1378) was 3x faster than control (?0.0497) trees demonstrating the effectiveness of liming.     

Spatiotemporal pattern analysis of Cacao swollen shoot virus in experimental plots in Togo

In order to quantitatively analyse the spatial pattern of cacao swollen shoot disease, particularly in cases of re‐emergence, three experimental plots were installed in a diseased area of cacao cv. Amelonado in Togo. After thorough cleaning and grubbing, the three plots were planted with less susceptible, hybrid plant material. Twenty years after replanting, a survey of healthy, diseased and dead trees was carried out during 2 consecutive years. Data were analysed using Ripley’s functions and join counts analysis. The re‐emergence of the disease occurred in patches or foci: following analyses with the two statistical methods, diseased trees and dead trees were found to be clearly aggregated on the three observed plots for the 2 years. The observed progress of the disease was not the same on the three plots and seemed dependent on the disease state of the first year: the higher the attack rate of the first year, the faster the disease progression. The use of less susceptible plants helped keep the land productive for 15 years. In conclusion, uprooting of the first infection focus can extend the life of cacao plots.     

Cultivating cacao Implications of sun-grown cacao on local food security and environmental sustainability

The reasons why upland farmerson the Indonesian island of Sulawesi areengaged in a cacao boom and its long termimplications are addressed in the context ofprotected area management regulations, andpolitical and economic conditions inPost-Suharto, Indonesia. In the remote casestudy village of Moa in Central Sulawesi, wefound that while few households cultivatedcacao in the early 1990s, all had planted cacaoby 2000. Furthermore, the vast majoritycultivate cacao in former food-crop focusedswidden fields under full-sun conditions.Farmers cultivate cacao to establish propertyrights in light of a land shortage driven inpart by the prohibition of farming and forestproduct collecting in a nearby national park,and to secure a future source of income, aconcern that has been exacerbated byIndonesia's economic crisis. However,conversion of swidden fields to sun-grown cacaoconstrains future food productionopportunities, increases susceptibility todrought stress and potential soil nutrient andorganic matter losses, and increases householddependence on a commodity that is subject toextreme price volatility. These factors raisesignificant concerns for local food securityand agricultural sustainability.     

可可种质抗黑果病离体鉴定方法研究

利用可可离体叶片和离体果实鉴定可可种质对黑果病抗性的方法。结果表明：接种方法、接种物浓度、叶龄或果龄等因素影响离体叶片、果实黑果病发生程度;离体叶片接种鉴定方法最适条件是采用针刺法接种、接种物浓度3 × 107 个/mL、叶龄50～60 d;离体果实接种鉴定方法最适条件为采用滴接法、接种物浓度为3×105 个/mL、果龄2～3个月。采用离体叶片接种和离体果实接种方法均能鉴定出可可种质对黑果病抗性的差异,鉴定结果与田间成株期的抗病性表现基本一致。     

可可体细胞胚胎发生及植株再生体系的构建

以可可（TheobromaCac0L.）的子叶为外植体,通过体胚发生途径,诱导再生可可植株。各培养阶段的优化培养基和培养条件为∶（1）愈伤组织诱导培养基（PCG）∶改良DKW+2,4-D3.0mgL+KT1.0mg几+TDZ 0.01mgL,在28+2）℃（以下培养温度均同）温度条件下,暗培养20d,诱导率为96.67%;（2）愈伤组织增殖培养基（SCG）∶改良DKW＋2,4-D 3.0mgA+KT1.0mg九,暗培养20d;（3）胚状体诱导培养基（ED）∶改良DKW+Sucrose30gL,暗培养60~150d,胚状体诱导产生并发育成熟,胚状体的诱导率为333%;（4）成熟胚诱导成苗∶①PEC培养基为∶改良DKW+Ghrose20gl+Sucrose10gL,光照为16h/d,培养60d;②采用RD培养基∶改良DKW+BA1.5mgl+AA0.5mgl,光照为16h/,培养3090d后,可得到完整的植株,再生植株的诱导率为 42%。     

Quantitative trait loci analysis in Theobroma cacao using molecular markers. Inheritance of polygenic resistance to Phytophthora palmivora in two related cacao populations

Two related segregating populations of Theobroma cacao L. were analysed for their resistance to Phytophthora palmivora. The first F₁ population was obtained by crossing two susceptible cacao clones of Catongo (a highly homozygous genotype) and Pound 12(a highly heterozygous genotype) and the second population was obtained by backcrossing a single F₁ tree with Catongo. The genetic maps obtained for each population were compared. The F₁ map includes 162 loci and the backcross has 140 loci. The two maps, F₁ and BC₁, exhibit high co-linear loci organization covering respectively, 772 and 944 cM.Phytophthora resistance was assessed by measuring the size increase of a lesion at five (DL5)and ten days (DL10) after pod inoculation. Six different QTL were detected in the F₁ and BC₁ populations. One QTL was found in both populations, and appeared to be a major component of disease resistance, and explaining nearly 48% of the phenotypic variance in the F₁ population. The absence of some yield QTL detection in the BC₁ in comparison with the F₁ population is due to the lack of transmission of the favouring alleles for these QTL from the single F₁ tree used for the backcross. The phenotypic variance explained by the action of the quantitative trait alleles indicated that genetic factors of both major and minor effects were involved in the control of the character studied. QTL conferring increased resistance to Phytophthorawere identified in both susceptible parents, suggesting the presence of transgressive traits and the possibility of selection in cacao. Pleiotropic and epistatic effects for the QTL were also detected. Finally, the use of marker assisted selection (MAS) in cacao breeding programs is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Differences in chemical constituents between vascular bundles and nonvascular bundles of cacao (<Emphasis Type="Italic">Theobroma cacao</Emphasis> L.) hull

 Cacao (Theobroma cacao L.) hulls were physically separated into vascular bundles (VBs) and nonvascular bundles (NVBs) to investigate their chemical compositions and the structural features of abundant polyphenolic compounds. Glucose content was determined to be 21.4% for VBs and 17.5% for NVBs, together with xylose content as 13.1% for VBs and 2.8% for NVBs. In addition, uronic acid in NVBs (12.9%) was much higher than that in VBs (5.2%). The content of total (poly)phenolic compounds (35.9%–39.1%) quantified as Klason residues (KRs) and acid-soluble phenolic compounds (ASPs) were similar in both cell types, although there were great differences in the structural characteris-tics of polyphenolic compounds. The pyrogram of VBs clearly showed high intensities of guaiacol and 4-vinylguaiacol together with low intensities of catechol and 4-methylcatechol. On the other hand, that of the NVBs showed opposite trends. These results were confirmed by alkaline nitrobenzene oxidation based on total yields of vanillin and syringaldehyde. Therefore, the accumulation of various polyphenolic compounds in cacao hulls relies strongly on the cell type and is correlated with the development of a secondary wall. Received: October 9, 2001 / Accepted: April 15, 2002 Present address: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA Acknowledgments This project was partially supported financially by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology (no. 13375007). We thank Dr. Hadi S. Arifin, Faculty of Agriculture, Bogor Agricultural University, Indonesia, for collecting cacao fruits at the Rajamandala Cacao Plantation at Rajamandala in West Java. Correspondence to:K. Iiyama     

Shade Effects on Growth and Development of Cacao Following Two Years of Continuous Dry Season Irrigation

ABSTRACT

The deployment of plantain shade and irrigation (5- and 10-day) intervals) for enhancing survival, field establishment, flowering and pod production of field-grown cacao seedlings in the dry season was investigated. The effects of dry season irrigation was profound on cacao growth, field establishment (over 90% seedling survival) and development, flowering and pod production. For the non-irrigated moderately shaded cacao, about 30% of the transplanted seedlings survived and the achievable percent survival from the various shade-irrigation combinations ranged from 47–90%. Open sun in combination with 5-day irrigation interval had best results in term of growth (root and shoot development and biomass accumulation) and establishment, flowering and pod production. Lower values of air and soil temperatures were obtained for combination of irrigation and shade regimes (dense and moderate) and higher soil moisture contents. The shade-irrigation combinations ameliorated microclimate and enhanced growth and development, seedling survival, root and shoot development, advanced flowering and promoted uniform fruiting/pod production and total bean yield. The effects of dry season irrigation at 5- or 10-day intervals was profound on cacao growth, field establishment (over 90% seedling survival), flowering and pod production. Irrigated unshaded (open sun) cacao had best results in term of growth (root and shoot development and biomass accumulation) and establishment, flowering and pod production. The achievable percent survival from the various shade-irrigation combinations ranged from 47–90%. The drip irrigation strategy adopted ameliorated dry season terminal drought (hydrothermal stresses) and promoted cacao growth, survival and flower/pod production.