Cláudio Pagotto Ronchi

Ecophysiology of coffee growth and production

, which together account for 99% of the world coffee bean production. Thisreview is organized into sections dealing with (i) climatic factors and environmental requirements, (ii) root and shootgrowth, (iii) blossoming synchronisation, fruiting and cup quality, (iv) competition between vegetative andreproductive growth and branch die-back, (v) photosynthesis and crop yield, (vi) physiological components of cropyield, (vii) shading and agroforestry systems, and (viii) high-density plantings.

Growth and photosynthetic down-regulation in Coffea arabica in response to restricted root volume

Coffee (Coffea arabica L.) plants were grown in small (3-L), medium (10-L) and large (24-L) pots for 115 or 165 d after transplanting (DAT), which allowed different degrees of root restriction. Effects of altered source : sink ratio were evaluated in order to explore possible stomatal and non-stomatal mechanisms of photosynthetic down-regulation. Increasing root restriction brought about large and general reductions in plant growth associated with a rising root : shoot ratio. Treatments did not affect leaf water potential or leaf nutrient status, with the exception of N content, which dropped significantly with increasing root restriction even though an adequate N supply was available. Photosynthesis was severely reduced when plants were grown in small pots; this was largely associated with non-stomatal factors, such as decreased Rubisco activity. At 165 DAT contents of hexose, sucrose, and amino acids decreased in plants grown in smaller pots, while those of starch and hexose-P increased in plants grown in smaller pots. Photosynthetic rates were negatively correlated with the ratio of hexose to free amino acids, but not with hexose content. Activities of acid invertase, sucrose synthase, sucrose-P synthase, fructose-1,6-bisphosphatase, ADP-glucose pyrophosphorylase, starch phosphorylase, glyceraldehyde-3-P dehydrogenase, PPi : fructose-6-P 1-phosphotransferase and NADP : glyceraldehyde-3-P dehydrogenase all decreased with severe root restriction. Glycerate-3-P : Pi and glucose-6-P : fructose-6-P ratios decreased accordingly. Photosynthetic down-regulation was unlikely to have been associated directly with an end-product limitation, but rather with decreases in Rubisco. Such a down-regulation was largely a result of N deficiency caused by growing coffee plants in small pots.

Source strength increases with the increasing precociousness of fruit maturation in field-grown clones of conilon coffee (Coffea canephora) trees

In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripening, photo-assimilates should be transported to fruits in a period shorter than that found in intermediate- or late-maturing clones. We hypothesised that at a given source-to-sink ratio, a presumably greater sink strength in early-maturing clones relative to intermediate- and late-maturing individuals should be correlated to increased rate of net carbon assimilation (A) and greater photo-assimilate transport to the fruits. Overall, earlier-maturing clones displayed greater A rates than the intermediate-maturing clones, which, in turn, had higher A than their late counterparts. Changes in A were largely associated with changes in stomatal conductance. Only marginal alterations occurred in the internal-to-ambient CO2 concentration ratio, the carbon isotope composition ratio, soluble sugars and chlorophyll a fluorescence parameters. Some changes in starch pools were detected among treatments. To the best of our knowledge, this is the first report showing evidence that increased precociousness of fruit growth and maturation results in higher A and thus increased source strength, a fact associated to a large degree with higher stomatal aperture.

THE EFFECTS OF PRUNING AT DIFFERENT TIMES ON THE GROWTH, PHOTOSYNTHESIS AND YIELD OF CONILON COFFEE ( COFFEA CANEPHORA ) CLONES WITH VARYING PATTERNS OF FRUIT MATURATION IN SOUTHEASTERN BRAZIL

The economics of coffee plantations is intrinsically linked to pruning, which can improve the canopy architecture and thereby increase productivity. However, recommended pruning times on conilon coffee plantations have been made on an entirely empirical basis. In this study, by evaluating growth, photosynthetic gas exchanges, starch accumulation and crop productivity, the effects of pruning at different times between harvest and flowering were investigated for six conilon coffee clones with distinct stages of fruit maturation (early, intermediate and late). Clones with an early maturation stage were pruned at four different times: 0, 30, 60 and 90 days after harvest (DAH). Intermediate clones were pruned at 0, 30 and 60 DAH, and late clones were pruned at 0 and 30 DAH. Overall, the rates of shoot growth and net photosynthesis, the stomatal conductance and the crop yield were not affected by the pruning treatments in any of the clones. In addition, pruning times did not affect the concentrations of starch or the photochemical efficiency of photosystem II. The carbon isotope composition ratio was marginally affected by the treatments. These results suggest that the pruning time after harvests is relatively unimportant and pruning operations can be scheduled to optimise the use of labour, which directly impacts the production costs of coffee.

INTERAÇÃO ENTRE TAMANHOS DE VASO E DOSES DE GLYPHOSATE NO CONTROLE DE BRAQUIÁRIA

The aim of this work was to evaluate pot size and glyphosate rate interaction on the growth, physiology and control of Brachiaria decumbens weed. It was sowed in 2, 5, 10 and 20 L-pots, which were kept in greenhouse. Plant growth was assessed from 41 to 63 days after plant emergence (DAE). Glyphosate was applied to all pot sizes at 0.0, 0.8, 1.6 and 3.2 kg ha-1, at 64 DAE. Leaf gas exchange was assessed along with chlorophyll fluorescence at two days after application (DAA); weed control level at 7, 14, 21 and 28 DAA; weed dry matter at 28 DAA; and weed sprouting dry matter at 28 days after weed cutting. B. decumbens growth increased linearly with increased pot size. Both weed gas exchange and chlorophyll fluorescence parameters were affected by glyphosate rates, but not by pot size. No significant interaction between glyphosate doses and pot size on weed control levels was found, but it increased strongly with increasing herbicide rates and only slightly with pot size, particularly up to 14 DAA. Weed dry matter at 28 DAA and plant regrowth differed according to pot size and glyphosate dose interaction. It was concluded that pot size should be precisely chosen to test systemic herbicide efficacy on the control of B. decumbens.

Optimizing the width of strip weeding in arabica coffee in relation to crop age

The aim of this study was to determine the weed strip control (WSC) required for adequate coffee growth after transplanting. A non-irrigated, field-planted (spaced 3.80 x 0.70 m) crop was used. The experimental design was a randomized block, with four replicates. The treatments were arranged in a 9 x 18 split-plot design to test the WSC of 0, 15, 30, 45, 60, 90, 120, 150, and 190 cm, which involved continuously hand-weeding at each side of the coffee row, and 18 coffee growth measurements. Multiple regression analyses were carried out relating to growth-variables as a function of both WSC and growth-evaluation times. Brachiaria decumbens was the main weed accomplishing 88.5% of the total weed dry mass. The minimum width of the WSC increases as the crop ages after transplanting. Assuming reductions of 2% and 5% in the maximum coffee growth, the recommended WSC was 75 and 52 cm at 4 months after transplanting (MAT), 104 and 85 cm at 6 MAT, 123 and 105 cm at 9 MAT, 134 and 116 cm at 12 MAT, 142 and 124 cm at 15 MAT, and 148 and 131 cm at 18 MAT, respectively. It was concluded that integrated weed management in young coffee crops must focus on the weed control only in a minimum range along coffee rows, which increases with coffee plant age, keeping natural vegetation in the inter-rows.

Micorrização, nodulação e produção da soja roundup ready após a aplicação de diferentes formulações de glyphosate

The aim of this study was to evaluate the effect of different glyphosate-based formulations on mycorrhizal colonization and nodulation in soybean cultivar RR TMG 125. The experiments were conducted under field conditions in Red-Yellow Latosol, during 2010/2011 and 2011/2012. The formulations Trop®, Roundup Original®, Roundup Ultra®, Roundup WG®, Roundup Transorb R® and ZappQi® were used at a glyphosate dose of 720 g a.e. ha-1. The experiment was arranged in a randomized block design with four replications and two controls (hoed control and non-hoed control). The variables shoot, nodule dry matter, and soybean yield were not influenced by the different formulations of glyphosate. For mycorrhizal colonization, it was verified that a positive effect of the herbicide Roundup Original® regarding the hoed control was not continuous in the two years of the experiment. The variable number of nodules was the most affected by the glyphosate formulations tested.

Períodos de interferência de plantas daninhas na cultura do girassol

A interferencia de plantas daninhas na cultura do girassol pode reduzir significativamente a produtividade de aquenios. O objetivo deste trabalho foi determinar o Periodo Anterior a Interferencia e o Periodo Total de Prevencao a Interferencia da comunidade infestante sobre a produtividade de aquenios e de oleo da cultura do girassol. O experimento foi conduzido em campo, na area da Faculdade de Ciencias Agronomicas FCA/UNESP, na Fazenda Experimental Lageado, municipio de Botucatu (SP), no ano agricola de 2007/2008. O delineamento experimental foi o de blocos casualizados, com quatro repeticoes. Os tratamentos foram compostos por parcelas constituidas por periodos de controle e de presenca de plantas daninhas. Para os periodos de controle, a cultura foi mantida livre das plantas daninhas pelos periodos crescentes de 7, 14, 21, 28, 35, 42, 49 e 110 dias apos a emergencia do girassol. Para os periodos de convivencia, a cultura foi mantida na presenca da comunidade infestante pelos mesmos periodos. Foram avaliadas as seguintes variaveis: Diâmetro de capitulos, produtividade de aquenios, rendimento de oleo de girassol, densidade e materia seca das plantas daninhas e indices fitossociologicos. O periodo anterior a interferencia foi de 35 DAE da cultura para a produtividade de aquenios, sendo que o periodo total de prevencao a interferencia estendeu-se ate 24 DAE. Para o rendimento de oleo, o periodo anterior a interferencia foi de 25 DAE, enquanto que o periodo total de prevencao a interferencia prolongou-se por 14 DAE.

Seletividade e controle de plantas daninhas com oxyfluorfen e sulfentrazone na implantação de lavoura de café

This study aimed to evaluate oxyfluorfen and sulfentrazone selectivity and weed control in young coffee plantations (Coffea arabica cv. Red Catuai). Three trials were conducted in a randomized complete block design, with 10 treatments and four replicates. In the first and second trials, at 30 and 90 days after transplanting (DAT), respectively, two doses of oxyfluorfen (0.36 and 0.72 kg a.i. ha-1) and sulfentrazone (0.4 and 0.6 kg a.i. ha-1) were tested by spraying the herbicides directly into soil (with seedling protection) or onto the total area. The same herbicides and doses were used in the third trial, but at 300 DAT and only directed to the soil, using two sprayer nozzles with different drift potentials being tested. Two additional control plots were added: hand-weeding control and weedy treatments. Weeds present in the inter-row spaces were eliminated by mowing operations. Weeds and their densities were identified. The toxicity of the herbicides to the coffee plants and its effectiveness in controlling the weeds were assessed. The main weed occurring in the experimental area was Brachiaria decumbens. Visual symptoms of herbicide toxicity were observed only when the herbicides were applied in the entire area (trials 1 and 2), regardless of their doses and application times. At the third herbicide application trial, no visual symptoms of herbicide toxicity and no reductions in plant growth were observed, regardless of the herbicide, the dose and the sprayer nozzles tested. At all times, a very good weed control percentage was obtained, but selectivity occurred only when the herbicides were not applied onto the total area.