The experiment was carried out at the Bananal do Norte Experimental Farm of the Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (Incaper), located at 20º45' S and 41º17' W, in Espírito Santo state, southeast Brazil. The site, at 140 m of altitude, has an undulating topography and a Cwa climate with rainy summers and dry winters according to the Köpen classification, precipitation and average annual temperature of 1,200 mm and 23°C respectively. The region has three dry months (June, July and August) with local variations to semi-humid from four to five months (May to September). The average maximum temperature of the warmest months is approximately 33.0°C and the average minimum temperature of the coldest months is 14.3°C.
The conilon coffee tree clones (Coffea canephora Pierre ex A.Froehner) were evaluated in two different environments, one being the agroforestry system and the other the intercropping. The agroforestry system is composed of rows of “urograndis” hybrid eucalyptus trees (Eucalyptus grandis W.Hill x E. urophylla S.T.Blake) and prata-type banana herbs (Musa spp.) spaced 5.0 m apart, surrounding two conilon coffee lines spaced 2.5 m between rows and 0.8 m between plants. In the intercropping, the ‘Bahia’ sweet orange trees (Citrus sinensis (L.) Osbeck) are arranged at 5.0 m between plants and between cultivation lines, and the coffee trees are positioned 2.5 m from the orange trees lines and 0.8 m from each other. Eucalyptus trees, banana herbs and orange trees were implanted in 2017 following the fertilization and liming recommendations for the state of Espírito Santo (Prezotti et al. 2007). The banana herbs were managed in the “Mãe-Filha-Neta” system, which consists of eliminating excessive shoots, allowing up to three aerial stems (composed of pseudostem, leaves and reproductive parts) of different ages per clump. The implantation, management, nutritional and phytosanitary management of the conilon coffee tree followed the current recommendations for C. canephora (Ferrão et al. 2019).
In May 2021 the coffee trees were implanted in Federer's enlarged block design (Federer 1956), with two plants per plot, with four controls, in six blocks in the agroforestry system and four for the intercropping. Ninety clones of different origins were evaluated, some from the genetic improvement program of C. canephora from Incaper, elite clones of commercial varieties and genotypes from crops in the south of the state of Espírito Santo. The four controls used were: Control 1 (T1 – clone 3 of the variety 'ES8142 – Vitória'); Control 2 (T2 - clone 5 of the variety 'ES8122 – Jequitibá'); Control 3 (T3 - clone 9 of the variety 'ES8112 - Diamante'); Control 4 (T4 – clone 2 of the variety ‘ES8132 – Centenária’).
At six, 12 and 18 months after planting the coffee trees, the following morphophysiological characteristics were evaluated:
1. PH: Plant height was measured with a graduated ruler, by the length of the largest orthotropic branch (cm);
2. SBD: Stem base diameter was measured with a precision digital caliper (0.01 mm) in the intermediate position of the soil up to the first plant node perpendicular to the planting line (mm);
3. CH: Canopy height was measured with a graduated ruler, by the vertical distance between the beginning of the coffee tree canopy and its end (cm);
4. NPB: Number of plagiotropic branches per plant was estimated by directly counting the number of plagiotropic branches of the coffee tree (unit);
5. NDVI: Normalized Difference Vegetation Index was measured with a PlantPen NDVI-300 portable sensor (Photon Systems Instruments PSI, Drásov, Czech Republic), using two leaves of the third or fourth pair, from the plagotropic branch, from the middle position of the plant (unit);
6. SPAD: Chlorophyll Index was obtained with the aid of the portable sensor SPAD-520 (Soil Plant Analysis De-velopment), measuring two leaves of the third or fourth pair, from the plagotropic branch, from the middle position of the plant (unit);
7. NN: Number of nodes was measured by directly counting nodes in the largest orthotropic branch of the plant (unit);
8. MIL: Mean internode length was obtained by the ratio between CH and NN;
9. NL: Number of leaves, was obtained by counting the number of leaves in the plant (unit);
10. ALU: Unit leaf area (cm²) estimated by the equation of Schmildt et al. (Schmildt et al. 2015) (Eq. 1)
$$ALU=0.6723 + 0.6779*\left(LL*LW\right)$$
1
where LL is the leaf length, it was measured with a graduated ruler, measuring the length of the leaf from the base to the apex of the leaf blade, in the longitudinal direction. Leaves of the third or fourth pair were used, in the plagiotropic branches of the middle third of the plant, starting from the apex of the branch in the direction towards the center of the coffee tree canopy (cm); LW is the leaf width, it was measured with a graduated ruler using the leaf evaluated for LL, measuring the largest width of the leaf in the transverse direction (cm);
11. ALT: Total leaf area, was estimated by the product of NL and ALU (cm²);
12. CV: Canopy volume (m³) estimated by the equation of Favarin et al. (Favarin et al. 2002) (Eq. 2)
$$\text{C}\text{V}=\frac{\left(\frac{{\pi }{*CDA}^{2}\text{*}\text{C}\text{H}}{12}\right)}{1000000}$$
2
where CDA is the canopy diameter average of the coffee tree, was estimated by the average between canopy diameter of the coffee tree in the transverse direction and canopy diameter of the coffee tree in line;
13. LAI: Leaf area index (m².m-²) estimated by the equation of Favarin et al. (2002) (Eq. 3)
$$\text{I}\text{A}\text{F}=0.0134 + 2.7791\text{C}\text{V}$$
3
The NDVI, SPAD, LL and LW measurements were performed on the same leaves.
Data analysis was performed using the restricted maximum likelihood method and best linear unbiased prediction (REML/BLUP), using the Selegen software (Resende 2007a; Resende 2016), model 70, applied to block designs increased with random effects witnesses, according to Eq. 4 below.
$$\text{y}={\text{X}}_{\text{m}}+{\text{Z}}_{\text{g}}+{\text{W}}_{\text{b}}+{\text{T}}_{\text{p}}+\text{e}$$
4
where y is the data vector, m is the vector of the effects assumed to be fixed (measurements), g is the vector of the genotypic effects (assumed to be random), b is the vector of the environmental effects of blocks (assumed to be random), p is the vector of the effects of permanent environments (assumed to be random), and e is the vector of errors or residuals (random). The capital letters represent the incidence matrices for these effects.
The significance of the random effects of the statistical models was tested using the likelihood ratio test (LRT) according to the following expression:
$$\text{L}\text{R}\text{T}=-2\left(\text{L}\text{o}\text{g}\text{L}-{\text{L}\text{o}\text{g}\text{L}}_{\text{R}}\right)$$
5
where, LogL is the logarithm of the maximum (L) of the restricted likelihood function of the full model; and LogLR is the logarithm of the maximum (LR) of the restricted likelihood function of the reduced model (without the effect being tested).
The selection of superior clones was performed using the Mulamba-Rank index (Resende 2007b). This index consists of classifying the genotypes in order of performance for each trait then calculating the average rank of each genotype for all categories. Based on the results of this index, the gains from selection were estimated, considering the predicted genotypic values of the selected.