Toshio Igue

Resistência de soja a insetos: VI. Comportamento de genótipos em relação a percevejos

The performance of 35 soybean germplasms including 16 cultivars, 6 plant introductions and 13 lines derived from the soybean improvement program against stink bugs, was evaluated for two consecutive years, 1983/1984 and 1984/1985, in relation to the stink bugs (Hemiptera, Pentatomidae) species Piezodorus guildinii (Westwood), Euschistus heros (F.) and Nezara viridula (L.). The two experiments were conducted under field conditions at the Experimental Center of Instituto Agronomico located in Campinas, State of Sao Paulo, Brazil. A complete randomized block design with 35 treatments and 4 replications was used. The individual plot was a single row 2 meters long. Artificial infestations with adults were made to supplement the natural field infestation of stink bugs. The infestation level was moderate in the first year and severe in the second. Three criteria were used to judge the resistance to stink bugs: the percentual index of pod damage, the percentage of foliar retention after pod maturation and yield. The percentual index of pod damage is given by the formula 1/2 (% of pods with intermediate damage) + % of pods completely damaged. The percentage of foliar retention was visually estimated upon maturation of the pods. The cultivar Parana was the most susceptible treatment being recommended for use as a susceptible check for stink bugs. The lines IAC80-4228 and IAC80-598-2-4, obtained through the soybean breeding program for resistance to stink bugs, had good performance. They still present however some undesirable agronomic features and cannot be recommended for distribution to the farmers.

Preferência de alimentação de adultos de Diabrotica speciosa (Germar) e Cerotoma arcuata (Oliv.) em variedades de soja

The preference for feeding in 5 soybean varieties of two species of leaf beetles, D. speciosa (Germar) and C. arcuata (Oliv.) (Coleoptera, Chrysomelidae) was tested at Campinas, State of Sao Paulo, Brazil, under greenhouse conditions, in a free choice type of experiment. Two Brazilian commercial soybean varieties Santa Rosa and Parana, were compared with the PI 227 687, PI 229 358 and PI 171 451. The PI 227.687 was less preferred for feeding by D. speciosa than the commercial varieties and the other two PIs were intermediate. The C. arcuata leaf beetle showed a significant preference for young leaves of the variety Santa Rosa over the young leaves of PI 227.687, but in general there was no conspicuous feeding preference for the commercial varieties as much as there was for D. speciosa.

EFEITOS DOS PERÍODOS DE COMPETIÇÃO DO MATO NA CULTURA DO AMENDOIM: I. SAFRA DA SECA DE 1988

A field experiment was carried out at Adamantina, State of Sao Paulo, Brazil, to study different periods of weed competition with peanut. The treatments were 20: with and without weed presence through the crop cycle and those resulting from factorial combinations among presence and ausence of weed in the beginning of crop and the time of weed removal - 20, 30, 40, 50, 60, 70, 80, 90 and 100 days after sowing. Each plot was constituted of four lines, with common border among experimental units, with useful area reading 6.0 m2. Weed species, occurring with higher frequencies were Cyperus lanceolatus Poir., Digitaria horizontallis Willd., Brachiaria decumbens Stapf. and Portulaca oleracea L. The weed association with the peanut crop decreased pod and kernel yields and peanut dry matter. No weed effects were observed on harvest indexes and shelling percentages in any of the studied periods. A weeding operation done eight or 73 days after sowing, for treatments without and with weeds respectively, was sufficient for obtaining peanut pod yields statistically similar to those obtained when the peanut crop was maintained without competition during all cycle.

Efeitos da cobertura e da incorporação ao solo, imediatamente antes do plantio, de diferentes formas de matéria orgânica não decomposta, na cultura do feijoeiro

The main objective of the present experiment has been the study of the behavior of organic matter, i. e., non decomposed mass of leguminous and gramineous plants when incorporated into the soil right before the planting time of dry beans and its effects. Data obtained showed that the incorporation of non decomposed plant mass had the following results: (a) moisture was retained in a greater degree and temperature variations were somewhat reduced, although it was in fact less efficient than mulch; (b) there was a tendency of forming a larger number of nodules in the roots, especially when gramineous plants were incorporated, even if this is not directly related to higher productivity; (c) increase in the content of potassium in the leaves, in the development of the plant and root system and in the seed production of dry beans. These effects were particularly significant when soybeans were applied, either incorporated into the soil or as top dressing.

Adubação NK em três variedades de cana-de-açúcar em função de dois espaçamentos

Two factorial field experiments were carried out in the years of 1981 to 1984, in two soils (Dark-red Latosol - LE, and Dusky-red Latosol - LR) of the State of Sao Paulo, Brazil, with the objective of assessing the effect of N and K application on yield of three varieties of sugarcane grown in two row spacings. The fertilizer treatments for plant-cane consisted of the following combinations of N and K2O, in kg/ha: 0-210, 70-210, 140-210, 210-210, 140-0, 140-70, 140-140, and 140-210. All plots received equal amounts of P, at the rate of 120 kg P2O5/ha. The fertilizer treatments for 1st and 2nd ratoon were the same for all plots: 100, 30, and 120 kg/ha of N, P2O5, and K2O, respectively. Significant effects of row spacings, varieties, and NK application were observed on yields of cane and sucrose in both soils. Maximum calculated yields of cane were obtained with 165 kg N/ha and 148 kg K2O/ha in the LR soil, and 180 kg N/ha in the LE soil. The corresponding values for maximum sucrose yields were 153 kg N/ha and 104 kg K2O/ha in the LE soil and 128 kg K2O/ha in the LR soil. The highest rates of both N and K applied caused a decrease in the sucrose concentration of cane so that the rates of fertilizer application necessary for maximum sucrose yield were lower than those for maximum cane yield. The data for total cane and sucrose production (plant + ratoon) showed that the effects of N and K were similar to those obtained for plant-cane. The 1.2-meter row spacing produced higher yield of cane per unit area than that of the 1.5-meter spacing (increases of 14% in LR and 7% in LE, for plant + ratoon), and lower values per unit length of row (- 18% in LR and - 10% in LE). Varieties IAC58-480 and IAC64-257 showed greater sucrose yield than that of IAC52-150: 17% and 12% respectively in LR; in LE, both varieties produced 12% more than IAC52-150. Varieties also differed regarding sucrose content: IAC58-480 was 5% higher than IAC52-150 and the latter was 2% higher than IAC64-257.

Efeito de três fertilizantes acidificantes sobre a concentração de alumínio e de manganês em folhas e raízes de cafeeiros

Foi determinada a concentracao de aluminio e de manganes em folhas de cafeeiros cultivados em vasos com tres solos diferentes e com aplicacao de tres fertilizantes nitrogenados acidificantes (nitrato de amonio, ureia e sulfato de amonio) e um nao acidificante (salitre-do-chile), alem de dois tratamentos extras com corretivos de acidez e um com enxofre. Nas raizes estes elementos foram tambem determinados para os tratamentos que receberam ureia, ureia mais enxofre e o controle sem nitrogenio. Nos tres solos determinou-se o efeito dos tratamentos sobre o pH e a concentracao de A13+ e Mn3+. A analise foliar revelou diferencas significativas entre tratamentos na concentracao de aluminio e manganes das folhas e em todos os tres solos estudados. Alguns sintomas especificos observados nas folhas e raizes estiveram associados a presenca de niveis elevados de manganes nessas partes vegetais.

Efeitos da adubação NPK nos teores de macronutrientes das folhas de cana-de-açúcar (cana-soca)

Foram utilizados oito ensaios de adubacao NPK, em cana-soca do cultivar CB41-76, conduzidos em diversos solos do Estado de Sao Paulo, sendo quatro em Latossolo Roxo, um em Latossolo Vermelho-Amarelo textura argilosa, um em Latossolo Vermelho-Amarelo textura media, um em solos Podzolizados de Lins e Marilia variacao Manilha e outro em variacao Lins. Aos quatro meses de idade da cana-soca, amostras de folhas + 3 foram coletadas para fins de analise de macronutrientes. As variacoes dos teores de macronutrientes foram mais acentuadas entre localidades do que entre doses dos respectivos adubos. Correlacoes positivas e significativas foram obtidas somente entre os teores de potassio nas folhas e as producoes de cana. Devido as variacoes acentuadas dos teores de macronutrientes nas folhas de cana-soca em relacao a diferentes localidades, as seguintes faixas de teores de nutrientes poderao ser, provisoriamente, consideradas como adequadas: N - 1,53 a 2,22%; P-0,14 a 0,20%; K - 1,24 a 1,59%; Ca-0,38 a 0,71%; Mg - 0,11 a 0,20% e S-0,11 a 0,31%.

Calagem e adubação nitrogenada e potássica para o cafeeiro

Liming of coffee crop is based on soil analysis of samples from the projection of the crown, which is the most acidic part of the soil due to nitrogen fertilization. This procedure is doubt ful since there are less acidic areas of the soil, mainly in the mid rows, due to the accumulation of bases promoted by squaring. Another problem of coffee management is the routine use of NPK formulas with high N and K contents, independently of the actual need of the crop. In this paper the effects of liming, nitrogen and potassium fertilization were studied in two plantations that had received normal application of these insumes. A fractional factorial design 1/2 (4 x 4 x 4) was used, with the following amounts of applied treatments: limestone - 400, 1,600, 3,600 and 6,400 kg/ha; nitrogen - 64, 121, 196 and 289 g/hole; potassium (K2O) - 36, 81, 144 and 225 g/hole. The experiments were performed in Garca, State of Sao Paulo, Brazil, on a lins-and-marilia-podzolized soil. Five crops were recorded from 1987 to 1992. Nitrogen produced the largest yield increases, although not very high, followed by liming; potassium did not affect yields. In the case of liming, low responses were obtained in spite of the fact that the observed base saturation values were much lower than the recommended 70%. Leaf nitrogen contents were rather high, which explained the fair response of the coffee tree to nitrogen fertilization. Medium to high levels of potassium were found in the 0-20 cm soil layer and medium contents in the 20-40 and 40-60 layers, which explained the lack of response to this nutrient. It can be concluded that it is necessary to review the actual base saturation needs for liming coffee. Nitrogen fertilization can be based on leaf and potassium on soil analyses.

Melhoramento da cana-de-açúcar. II. Experimentos regionais com clones obtidos em 1964

Three experiments were conducted in 1971 with clones obtained by hybridization in 1964, using a lattice design. These experiments were located in the Sertaozinho, Ariranha and Tapiratiba counties of the State of Sao Paulo. The checks utilized were the commercial varieties CB41-76, IAC50-134 and IAC51-205. Sugarcane was harvested thrice, that is plant cane (18 months), first ratoon (12 months) and second ratoon (12 months). The clones that showed good performance received the prefix IAC which were 64-257, 64-328, 64-306, 64-276, 64-368, 64-321 and 64-304.

Adubação mineral do feijoeiro: V - Efeitos de N, P, K, S e de uma mistura de micronutrientes, em dois solos do Vale do Paraíba

Eight experiments were conducted in the State of Sao Paulo to study the effects of several fertilizar treatments on the yields of dry beans. Phosphorus induced significant increases in three localities, nitrogen, in one, and potassium, only in the second year of one experiment conducted for two years. The addition of sulfur or a mixture of micro-nutrients to NPK fertilizer did not modify significantly the yields in any of the localities. The residual effects of phosphorus and the mixture of micro-nutrients, observed in three of the experiments, were higher than the direct effects.