José Osmar Lorenzi

Variação na qualidade culinária das raízes de mandioca

Irregular culinary quality of cassava roots has been one of the major point that restricts its expansion for human consumption. A good quality cassava root, after cooking and smashing with a fork, results in a no stick mass, quite plastic and without grooms. Cooking time is closely related to the quality of the cooked mass, i.e., the shorter it takes to cook, the better the mass produced. Therefore, in this work, the duration of cooking time (DCT) was used as an express method for evaluating culinary quality of cassava roots. Variations in DCT may be related to two group of factors: a) intrinsic - which takes into account within the root variability, root to root, as well as differences among plants of the same variety; b) extrinsic - which considers the effects of plant genotype, environmental conditions and physiological phase of the plant. The main objective of this work is to verify and quantify how DCT was affected by the described factors. Preliminary studies were performed under field conditions at Instituto Agronomico, Campinas, State of Sao Paulo, Brazil, using five contrasting cultivars grown up in two different soil types. Root samples were taken monthly from the 7th to the 15th month after planting. DCT was determined with sub-samples of each root of the plant and starting of cooking time was considered at the moment in which roots were immersed in the boiling water. Results indicate that: a) average DCT decreased 12 min from the base to the tip of the root; b) within the same plant, DTC varied from 11, 10 and 27 min at the age of 8, 12 and 15 months respectively; c) difference among cultivars harvested with the age of 7-15 months was 9 min and when soil type was included in the analyses it reached 17 min; d) lowest DCT was observed for harvestings between 7-12 months after planting.

ACÚMULO DE MATÉRIA SECA NA PRESENÇA E NA AUSÊNCIA DE PLANTAS INFESTANTES NO CULTIVAR DE MANDIOCA SRT 59 - BRANCA DE SANTA CATARINA

The period for cassava planting is very wide in Sao Paulo State, Brazil, covering the whole dry season (May to October). There are large differences in the plant growth and its interference with the weed community when the planting time is early or late in the dry season. Aiming to study the weed interference on cassava growth and productivity, four field assays were carried out under different planting times (06/28/1989, 06/30/1989, 10/30/1989, and 07/23/1990) in a randomized complete blocks experimental design with three or four replications. The treatments were divided in two groups: in the first one (group 1), the crop was maintained weedy from the planting date to 30, 60, 90, 120, 150, 180, 210, 240, 270 and 360 days. In the second group (group 2), the crop was kept weed free from the planting date to 30, 60, 90, 120, 150, 180, 210, 240, 270, and 360 days. The weed interference reduced drastically the dry matter accumulation by the cassava plants and the root production losses reached up to 90%. The increase in the rate of dry matter accumulation in the cassava roots in the presence of weed could not be analyzed in two assays. In the group 2, all the data were properly analyzed in the four assays. The Boltzman Sigmoidal Equation suited well the data on cassava root dry matter accumulation and provides good prediction models. The best dry matter production was obtained for 360 day old roots.

Efeito da densidade populacional e época de colheita na produção de raízes de mandioca de mesa

In sweet cassava production, economic yields of high quality roots are obtained only after a growing season of eight to ten months. In addition, cassava plants under little competition present higher yields per plant. The objective of this work was to study the handling of population densities in the sweet cassava crop, as a tool to obtain high yield of high quality roots in earlier harvests. Seven plant densities, from 5,000 to 20,000 plants ha -1 , were tested with growing cycles of six, eight, ten, twelve, fourteen and sixteen months, in a field trial using the cv. IAC 576-70. Total root yields increased with time, being the highest values obtained with the highest plant densities. It was estimated, with a regression model, a maximum yield of 26.8 t ha -1 , when using 20,000 plants ha -1

Avaliação de cultivares de mandioca de mesa no Vale do Ribeira (SP)

The present paper reports a final evaluation of the best cassava clones for table, selected in the Ribeira Valley, State of Sao Paulo, Brazil, from a genetic basis of 306 cultivars of the germoplasm bank of the Agronomic Institute. Three experiments were carried out at the Pariquera-Acu Experimental Station, during the 1989/90, 1990/91 and 1991/92 seasons under a randomized design with 12 treatments (cultivars) and four replications. The most relevant results, were: (a) the cultivars had different root yields in relation to years. However, the cultivar IAC 576-70 was the most productive, with a yield of 34.3 t/ha in average, meanwhile the cultivar used as test plant showed an average yield of 17.8 t/ha; (b) the results of the cooking tests were not significant for the relationship cultivar x year interaction. The local cultivar presented the lowest average cooking time of 26 minutes in boiling water.

Variação de carboidratos e ácido cianídrico em raízes de mandioca, após a poda da parte aérea

Data are presented on the variation of the level of dry matter, cyanide, starch, total soluble carbohydrates, and reducing sugars content in roots of 13 months old cassava (Manihot esculenta, Crantz) at successive stages after the total removal of the aereal portions. During the 14 days following pruning starch percentage decreased from 79.06% to 62.52%; total soluble carbohydrates and reducing sugars showed a variation from 7.65% and 1.55% up to 17.56% and 5.03% respectively. Total carbohydrate presented small losses by pruning probably due to the new sprouting process. Root cyanid content decreased from 67 to 35 ppm. Its has also been observed that at the 17th day after pruning, different levels of similar carbohydrates were recorded in the different root types as those from the base and the middle of the planted cutting and those from the plant stem base. Such variations are hypothetically ascribed to either a more intensive mobilization of stored carbohydrates or to larger differences of age and composition of each type of root since its origin. This suggests more detailed research work about root sampling method for laboratory analysis.

Acumulação de matéria seca e macronutrientes por dois cultivares de mandioca

Material collected in a field trial conducted in Dark Red Latosol (Typic Euthror-thox) was used to study dry matter and macronutrients accumulation in two cassava cultivars (Branca-de-santa-catarina and IAC-Mantiqueira). Plants received a uniform fertilization of N, P205 and K2O of 40, 80 and 60 kg/ha, respectively as ammonium sulfate, simples superphosphate, and muriate of potash; N was top dressed 60 days after the sprouting. Samples were taken at six occasions during the growing season, with an interval of sixty days between each sampling. The plants were divided into roots, leaves and stems and each part was analysed for N, P, K, Ca, Mg and S. The results showed that: a) The period of greatest dry matter accumulation was between 120 and 180 days after the sprouting of the plants, with the average of 105.0 kg.ha-1.day-1; b) Extraction of macronutrients was the same in the two cultivars, with the exception of P; export was different only in the case of K and S; c) The extraction, in kg/ha and kilograms needed for the production of one metric ton of roots were respectively 113.3 and 6.21 for N, 11.0 and 0.62 for P, 78.6 and 4.24 for K, 62.0 and 3.37 for Ca, 18.5 and 1.00 for Mg and 8.3 and 0.46 for S; d) The export, in kg/ha and kg/ton of roots were respectively 39.1 and 2.12 for N, 3.9 and 0.22 for P, 32.5 and 1.71 for K, 12.1 and 0.66 for Ca. 6.7 and 0.36 for Mg and 1.7 and 0.09 for S.

Avaliação de variedades de mandioca no estado de São Paulo

Quinze experimentos de variedades de mandioca (Manihot Esculenta Crantz) foram conduzidos e colhidos com dois ciclos vegetativos (18 a 24 meses), em varios municipios do Estado de Sao Paulo. Estes ensaios foram distribuidos em quatro series com nove, dez ou doze variedades cada uma. O delineamento estatistico utilizado foi de blocos ao acaso com quatro repeticoes. Foram efetuadas analises individuais e conjuntas dos experimentos. Os resultados mostraram que, em media, apenas a variedade IAC 12-829 (39,0t/ha) superou, estatisticamente, em producao de raizes, a variedade testemunha SRT 59 - Branca-de-Santa-Catarina (25,4t/ha).

Producao de sementes de mandioca em plantas com um e dois ciclos vegetativos

O presente trabalho teve por objetivo comparar a producao de sementes botânicas de mandioca entre campos anuais e campos conduzidos por mais um ciclo vegetativo. As plantas com dois ciclos vegetativos foram conduzidas sem poda e com poda a 10cm acima do solo. Os resultados mostraram que as plantas com um ciclo vegetativo produziram em media 31,70 sementes por planta, enquanto as de dois ciclos, podados ou nao, produziram, respectivamente, 23,39 e 64,64 sementes por planta. O tratamento sem poda, embora mais produtivo, apresentou dificuldades para os trabalhos de campo, tais como, praticas culturais e ensacamento dos frutos, devidas a arquitetura da parte aerea. Entretanto, tais dificuldades poderao nao ocorrer quando a cultura for conduzida em solos pobres.

Influência do armazenamento de ramas para plantio em algumas características agronômicas da mandioca

While weather is not appropriate for cassava planting, growers in the State of Sao Paulo, usually keep their planting material (stems) stored in different ways. It is used the horizontal or vertical heaping systems, being the first one more common. The use of the fresh-harvested stem for planting is rare. The objective of this work was to evaluate the storage systems, and none storage, of cassava (Manihot esculenta Crantz) stems on some agronomic and physiological aspects. Two cultivars and three types of cuttings were used in a 2 x 3 factorial experiment in a randomized block design with four replications. The cultivars used were IAC 12-829 and SRT 1287-Fibra, with high and low ability of branching, respectively. The types of cuttings were originated from fresh-harvested stems and from stems stored for 105 days period in horizontal and vertical heaping systems. The experiment was carried out during the 1991/1992 season, at the Vale do Paranapanema Experimental Station, Instituto Agronomico de Campinas, Assis, State of Sao Paulo, Brazil, in a Allic Dark Red Latosol, medium texture. The results showed that: (a) the storage of the stems in horizontal position lead to an increase in the number of primary shoots of the two varieties and increased the weight of the aerial part of the SRT 1287-Fibra; (b) SRT 1287-Fibra cultivar was more influenced by the horizontal storage than the IAC 12-829; (c) IAC 12-829 had superior root production, without differing from the SRT 1287-Fibra when the cuttings were derived from the horizontal storage stems; (d) the storage in the vertical position had a similar behaviour as the fresh-harvested stems.

Mandioca: distribuição no estado de São Paulo do micoplasma causador do superbrotamento-de-santa-bárbara-do-rio-pardo

Cassava is a basic food staple of poor families in Brazil and it is common for them to have backyard patches of cassava plants from which they dig roots for daily use. This is particularly true in houses lying on the outskirts of most small towns in the State of Sao Paulo, Brazil. A survey for new table cassava types was being carried out in 126 counties of this State, inspecting 5 to 10 patches adjacent to residences on the outlying parts of each county seat, when the Santa Barbara mycoplasma disease showed to be present in 12 out of the 126 counties. This disease occurred mostly in the counties near Aguas de Santa Barbara, the city where the disease was first recorded. In the other 114 counties no mycoplasma disease was noticed. Control measures such as propagation of cuttings only from healthy plants have provided good control of other types of cassava mycoplasma disease in large commercial plantings in the past. It is thought, however, the eradication of the Santa Barbara type of mycoplasma disease from cassava backyard patches is difficult to accomplish because the owners do not care for selecting healthy planting material and eliminating sick plants.