José Carlos Sabino

Fitorreguladores de crescimento e capação na cultura algodoeira

Estudaram-se, em dez experimentos de campo, os efeitos dos seguintes fitorreguladores de crescimento e da capacao na cultura algodoeira: cloreto de clorocolina, aplicado na dose de 50 g/ha; cloreto de chlormequat, 100 g/ha e cloreto de mepiquat, 100 g/ha. A capacao foi realizada manualmente, planta por planta, na mesma epoca da aplicacao dos fitorreguladores, aos 60-70 dias da emergencia das plantas. O delineamento estatistico foi de blocos ao acaso, com cinco tratamentos e seis repeticoes e, a variedade utilizada, a IAC 19. Para a avaliacao dos resultados de producao e altura de plantas, efetuaram-se dois agrupamentos de ensaios, sendo um com maior e outro com menor desenvolvimento, ou seja: plantas em parcelas testemunhas com altura superior e inferior a 100 cm respectivamente. As demais caracteristicas agronomicas e tecnologicas da fibra foram analisadas em um so grupo. Para o grupo de plantas com maior desenvolvimento, foi obtido, em media, um aumento de 16,3 e 8,4%, respectivamente, para o tratamento com capacao e aplicacao de fitorreguladores. O fitorregulador proporcionou, em media, reducao de 12,1% na altura das plantas e a capacao, em media, 20,8%. Os fitorreguladores, indistintamente, proporcionaram aumento de peso do tapulho e das sementes, enquanto, com a pratica da capacao, nao se verificou esse efeito. A aplicacao de cloreto de clorocolina resultou em menor porcentagem de fibra do que o cloreto de mepiquat.

Modo e época de aplicação de fosfatos na produção e outras características do algodoeiro

The traditional mode of phosphate application to cotton was compared with broadcasting application in a long term trial conducted on a DusKy Red Latosol, with a low level of phosphorus. Triple superphosphate was applied annualy (121 kg/ha of P2O5)in furrows at sowing, during six years, or broadcasted and incorporated, through one application (728kg/ha of P2O5) in the first year, or two applications in the first and fourth years (364kg/ha, at each time). A thermal phosphate (18% P2O5) was also tested in two broadcasting applications. All treatments were compared to a control, with constant doses of N and K, but without P. During the six years of phosphate fertilization, higher yields of IAC 18 cotton variety were obtained, with annual application at sowing time, except for the first year due to the low initial disponibility of P. High quantities of broadcasted phosphate led to visual potassium deficiency symptoms, with losses in yield, Micronaire index and maturity of fibers. Therefore, due to the good yield performance obtained with a moderate dose of phosphate, in the years of application, it was suggested that a combination between broadcast and localized application should be studied, in future experiments. Other characteristics of cotton such as boll and seed weight plus fiber length, also increased significantly with P fertilization. The residual effect of the traditional mode of phosphate application, studied during the last three years, with IAC 20 cotton variety, showed significant results only for yield.

Estudo do parcelamento da adubação potássica do algodoeiro

The advantage of split application of potassium chloride in cotton was studied in ten field experiments, conducted at different localities during the period of 1975 to 1981. In such cases, doses of 0, 60 and 120kg/ha of K2O, were placed in a fillet beside and below the seeds, at planting. In other treatments 1/3. 1/2, 2/3 or the total quantity of the highest level of potassium fertilizer was applied together with nitrogen, just after thinning, in a side-dressing operation, and covered slightly by subsequent cultivation. When all the K was applied at planting, linear effect on cotton yield appeared only in 10% of the experiments. This proportion increases to 40% when split applications were made. However, in combined analysis of all tests no significant difference was found between the two methods. Based in a study of simple correlations between cotton productivity and potassium application, expressed as the control treatments relative yield and indices of soil analysis ike 1/K+ and (Ca2+ + Mg2+)/K+, three groups of experiments were established, according to different expected responses. Considering the group of high expected responses [K 43], parcelled application resulted in increases of cotton yield when compared with the normal method of application. Similar tendency was observed in the group of intermediate expected responses [0.8-0.24 meq of K+ and 20-43 of (Ca2+ + Mg2+)/K+]. In potassium deficient soils split application of potassium chloride can be recommended, 1/2 or 2/3 of the total level furnished at planting and the remainder just after thinning, by side-dressing, mixed with nitrogenous fertilizer and followed by cultivation.

Melhoramento do trigo: XXIII. Avaliação de linhagens na região do vale do Paranapanema, em Capão Bonito e em Tietê, em 1984-88

Twenty two inbred lines from the wheat breeding program at the Instituto Agronomico of Campinas, plus the cultivars BH-1146, Alondra-S-46 and Anahuac were evaluated in six field experiments carried out at different locations of the Paranapanema Valley, during the period of 1984-88. Grain yield, plant height, number of days from emergence to flowering, percentage of lodged plants, head length, number of grains per spike and per spikelet, number of spikelets per head, weight of 100 grains, and resistance to stem and leaf rusts, to leaf spots due to Helminthosporium sp. and Septoria sp., and to powdery mildew were evaluated under field conditions. Tests for resistance to stem and leaf rusts and to aluminum tolerance, were performed in greenhouse and laboratory, respectively. The genotypes were also evaluated in trials carried out on acid soil at Capao Bonito and under high soil fertility condition at Tiete. At Paranapanema Valley and Capao Bonito the line 19 (CNT-9 x BH-1146) = IAC-227 showed good grain yield presenting medium cycle and medium plant heigth. At Tiete, jhe lines with a medium cycle from emergence to flowering were the most productive: 1 (Alondra-S-46 x IAC-5) = IAC-225 and 17 (Alondra-1 x IAC-5) = IAC-226, of short plants; and the line 3 (Alondra-S-46 x C-3), of tall plants. The line 21 (IAC-5 x Alondra-S-46) was resistant to: (a) two race mixtures of stem rust; (b) leaf rust, under field condition and two race mixtures of this rust, under greenhouse condition; (c) powdery mildew in adult stage of plants; and (d) leaf spots, showing a relatively low amount of them, under field condition. The lines 6 (C-3 x Sonora-64) and 17 (Alondra-1 x IAC-5) showed to be good genetic sources for long head, the line 17 for large number of spikelets and grains per head, the line 10 (Jupateco x IAC-13) for large number of grains per spikelet and the line 5 (Tobari-66 x BH-1146) for heavy grains. The lines 7, 9, 13, 16, 17 and 19 and the cultivar BH-1146 exhibited tolerance to the presence of 10 mg/liter of Al3+ in the nutrient solution.

Melhoramento do algodoeiro para resistência múltipla a doenças, nematóides e broca-da-raiz em condições de campo

Um modelo de selecao e teste de linhagens de algodoeiro para resistencia multipla a doencas e pragas, adotado pelos melhoristas da Secao de Algodao do Instituto Agronomico, e descrito e discutido com base nos dados obtidos no periodo de 1981 a 1991. Condideraram-se as murchas de Fusarium e de Verticillium, a ramulose, a mancha angular, os nematoides e a broca-da-raiz como fatores adversos. Foram sugeridos indices relativos de resistencia apropriados a cada fator e um indice de resistencia multipla para a avaliacao global dos resultados. Discutem-se as evolucoes desses indices durante o periodo, assim como as correlacoes observadas anualmente entre os indices. Houve, no periodo, tendencia para nivel crescente de resistencia para todos os fatores, com excecao da ramulose, cujo indice medio de resistencia oscilou ao redor de 70% da testemunha resistente, no conjunto das linhagens promissoras obtidas anualmente. As correlacoes entre os indices de resistencia aos fatores variaram ao redor de zero, de maneira casual de ano para ano, atingindo raras vezes o nivel de significância de 5%. Apareceram correlacoes negativas significativas, no final do periodo, entre ramulose, de um lado, e Verticillium e mancha angular do outro, cuja importância e consequencia sao discutidas. O indice medio de resistencia multipla cresceu de 56,7% no periodo, chegando a 0,776 no final, sendo que o valor 1,000 representaria a reuniao de todos os genes disponiveis de resistencia numa mesma linhagem.

Estudo regional da adubaçáo boratada do algodoeiro no Estado de São Paulo

After the confirmation of problems on cotton concerning boron nutrition in the State of Sao Paulo, Brazil, at the decade of 1970, experimental field tests were carried out and demonstrated the necessity of boron fertilization on deficient soils. With the purpose of evaluating the use of boron under different conditions, it was conducted a regional study through the Sao Paulo State cotton belt, during the period of 1979 to 1986. Rates of 0, 0.2, 0.4, 0.8, 1.6 and 3.2kg/ha of B as borax (11 % of B), were applied at planting time, in latin square design experiments. The variety IAC 17 was used during the four years, followed by the IAC 20. Boron fertilization consistently increased cotton yield, although statistically significant differences were obtained only in 20% of the events; the plants reacted better in terms of boron concentration in the leaf blade. Grouping the experiments by previous informations about use of liming and mineral manure, associated to the occurrence of boron deficiency or toxicity symptons, provided a good discrimination of B fertilization. The effect of boron was greater in tradicionally limed and fertilized (NPK) soils; it decreased on soils with acidity in phase of correction or corrected but previously fertilized with boron, and was negligible in crops after old pastures. There was a significant correlation relating cotton yield and soil boron determined with Mehlich solution (HCl 0.05M + H2SO4 0.0125M) or, specially, with hot water. Significant results were also observed in relation to yield and fifth leaf blade boron concentration. As a preliminary approach, analitycal values over ranges of 0.20-0.40 ppm and 25-40 ppm for soil boron extracted with hot water and for leaf blade boron concentration, respectively, were considered as indicative of the need for boron supplying in cotton fertilization.

Early grafting of macadamia-nut seedlings

The difficulty of obtainning good grafted seedlings has been a hindronce to establish commercial macadamia-nut orchards in Brazil. The current procedure takes from two to three years in the nursery for grafted macadamia to be transplanted in the field. This article reports an experiment where the grafting of macadamia seedlings raised in plastic bags was compared to the usual method of propagation. The results indicated the feasibility of making good one-year-old grafted macadamia-nut young trees.

Uso de sulfato de amônio e de uréia na adubação do algodoeiro

In order to compare the effect of ammonium sulfate and urea, when sidedressed and incorporated just after thinning, on cotton cv IAC 20, sixteen field experiments were conducted in different soils of the State of Silo Paulo, Brazil. The experiments were carried out during the growing seasons of 1984/85 to 1986/87. Rates of 0, 25, 50, 75, and 100 kg/ha of N were used in a factorial design (2 x 5), with four replications in randomized blocks. Two extra treatments were added in some experiments, in which the N sources were sidedressed without incorporation at the rate of 75 kg/ha of N. The highest yields and the smallest responses of cotton to N application occurred in soils previously covered with old pastures or grown with legumes in rotation. The most profitable rate of nitrogen fertilization, calculated for groups of experiments based on expected yields, varied from 17 to 88 kg/ha of N, the highest rates for soils more intensively cultivated. Yield responses to N could be reasonably predicted in soils grouped according to P extracted by ion exchange resin and, in some way, with the inorganic-N content of the 0-60cm soil layer. Soils with high available P, long under cultivation, showed high responses to N application than soils with median P levels. Nitrogen sources or methods of fertilizer application did not affect cotton yield and total N content of leaves; however, total S concentration in leaves decreased linearly with the increase of urea application. Total N around 3.8% is suggested as the critical limit for N in cotton, determined in blades of the most recently matured leaf, collected from the main stem, 80 to 90 days after planting.

Efeitos da calagem e da adubação potássica sobre características agronômicas e propriedades tecnológicas da fibra do algodoeiro

The effects of liming and potassium fertilization on the agronomic characteristics and technological properties of the cotton fiber were studied in a permanent trial on a Dystrophic Dusky Red Latosol, acid, of low fertility during growing seasons of 1976/77 to 1985/86. A split-plot design was used, dolomitic limestone being applied on the plots at the levels of 0, 2, 4 and 6 t/ha, while the doses of 0, 50, 100 and 150 kg/ha of K20, corresponded to the subplots. Lime was applied in the first year, and the experiment was conducted and reapplicated during 1981/82, while potassium was furnished annualy, at planting time, in mixture with NK fertilizers. Liming caused an increase in the mass of bolls and reduced the mass of seed, length, length uniformity, Micronaire index, maturity and fiber strength. Potassium fertilization caused an increase in mass of bolls and seeds, length uniformity, Micronaire index, maturity and fiber strength, when was applied, on the last, the correction of the Pressley values. Anyone interaction between lime and potassium was observed.

Efeito do parcelamento da adubação potássica nas características agronômicas e propriedades tecnológicas da fibrado algodoeiro

Data on agronomic characteristics and technological properties of cotton fiber obtained during six years in ten field experiments where the effects of parcelling potassium application are discussed. Potassium fertilizer was applied at planting in furrows at the rates of 0, 60 and 120kg/ha of K2O in the form of potassium chloride highest, rate being parcelled by providing 1/3, 1/2, 2/3 as side-dressing, together with nitrogenous fertilizer and lightly incorporated by bringing soil to the plants. The experiments were grouped according to the results obtained by linear correlation between relative production and the analytic index of soil the most related to plants responses to potassic fertilization. In the group of high expected response to the fertilizer, significant effects of potassic fertilization were observed on Micronaire, maturity of the fibers and on the average weight of 100 seeds and of bolls. The parcelling of application increased significantly the values of uniformity of length of fibers and, in general, contributed to improve the average values of all the other charactristics studied. The effect of potassium was significant, furthermore, for weight of boll in the group of medium to low expected response to fertilization. The results obtained allow to emphasize the recent recommendation that application of high doses of potassium chloride to cotton should be parcelled, about 1/2 to 2/3 of total K2O being provided at the planting furrow and the remainder by side-dressing, specially when there is deficiency of potassium in the soil.