Corn (Zea mays L.) cultivars tolerance to nicosulfuron

The effects of nicosulfuron on morphological, yield and growth characteristics and the histological modifications in the leaf blade were evaluated for eight corn cultivars: landrace popcorn, ESALQ-popcorn, Piranao, DSCC-Architecture, ESALQ VF7, ESALQ VD8, JAB 01F and JAB 02D. The experimental de sign was a randomized complete block with three replications in a factorial arrangement. Plots were four rows wide and 6.00m long with 0.90m spacing between rows and 0.20m between plants. Nicosulfuron was applied at the dose of 160 g a.i.ha(-1), when the plants was 25 cm high and has 5-6 expanded leaves. Nicosulfuron significantly reduced plant height at silking and the Final plant stand. There was also a significant reduction for plant height at 47 clays after sowing, for number of leaves, ear position. ear height, grain yield, ear weight and total number of ears due to nicosulfuron. The cultivars JAB 01 and JAB 02 were the least affected by the herbicide with similar yields to those of the control group, showing good tolerance to nicosulfuron. The leaves injury symptoms for all the studied cultivars consisted of chlorosis and puckering of the blades from the expanding central leaves of the plant at 7 days after application. Anatomical alterations in the epidermis due to the herbicide consisted of an increase in number and size of the bulliform cells and in the suppression of the epidermal cells in the epidermis and in the nearby of the vascular bundles. Some parenchymatic cells became voluminous and devoid of chloroplasts. SEM examination revealed a loss of bilateral symmetry of the stomata and disappearance of the subsidiary cells from the stomata near the midrib at the adaxial surface.

RAPD marker use for improving resistance to Helicoverpa zea in corn

Helicoverpa zea is responsible for great losses to the corn, Zen mays L., crops final productivity, and the best way to control it is by improving genetic resistance. In collaboration with corn improvement and increasing resistance to insects through molecular marker assisted selection, this work had as an objective the selection of resistant (RP) and susceptible progenies (SP) to H. zea based on the RAPD technique. Molecular markers were Found, among the resistant progenies and it is suggested that linkage of these within the Zapalote Chico corn race, be used to extract resistance genes from this race as a donor. The progenies were selected from a population of half-sibs exhibiting a broader genetic base (FCAVJ-VF14). After DNA extraction, two sample bulks were formed; one made up of the six most resistant plants, the other of the six least resistant plants. Eighty-six primers were tested for PCR reactions with the resistant and susceptible bulks and analyzed on agarose electrophoresis for the detection of RAPD band polymorphism. The results of the banding patterns and similarity values indicated a nucleotide sequence amplified by the primer OPC-2 as a possible molecular marker for the identification of resistant progenies and a homology region between them and the Zapalote Chico corn race.

Effect of citrus sudden death on yield and quality of sweet orange cultivars in Brazil

Citrus sudden death (CSD) has greatly affected sweet orange cultivars grafted on Rangpur lime in São Paulo and Minas Gerais States, Brazil. To characterize and quantify CSD damage, fruit yield and quality were assessed in each combination of sweet orange cultivar (Hamlin, Pera, Natal, and Valencia), age class (3 to 5, 6 to 10, and 11 to 15 years old), and CSD severity class (0 = no symptom, 1 = initial symptoms, and 2 = severe symptoms). For each combination, 10 trees were harvested and 20 fruit were taken for quality analysis. Damage was characterized by reduc_ tion of: (i) total weight of fruit/tree (36 and 67% for severity class 1 and 2, respectively), (ii) number of fruit/tree (27 and 55%), (iii) fruit size (13 and 25% in diameter and height [stem to styler distance]), (iv) fruit weight (32 and 56%), (v) total soluble solids (TSS)/fruit (18 and 42%), and increase of (vi) Brix (14 and 34%), (vii) acidity (16 and 41%), and (viii) TSS/90-1b. box (21 and 33%). There was no alteration on Brix/acidity ratio and percentage of juice on fruit of affected trees. Sweet orange cultivars did not differ in percentage of reduction or increase of all yield and quality variables, with the exception of Pera, which expressed increases of Brix and acidity. For more severe affected trees, the youngest plants showed a higher reduction in fruit number/tree, whereas plants 6 to 10 years old showed a higher increase in fruit acidity and TSS/box. However, no differences in percentage of reduction or increase for other variables were observed among different age classes. The damage to the above probably was associated with reduced water absorption capacity of CSD-affected trees.

Effect of steeping conditions (sulfur dioxide, lactic acid, and temperature) on starch yield, starch quality, and germ quality from the Intermittent Milling and Dynamic Steeping process (IMDS) for a Brazilian corn hybrid

Effect of lactic acid, SO2, temperature, and their interactions were assessed on the dynamic steeping of a Brazilian dent corn (hybrid XL 606) to determine the ideal relationship among these variables to improve the wet-milling process for starch and corn by-products production. A 2x2x3 factorial experimental design was used with SO2 levels of 0.05 and 0.1% (w/v), lactic acid levels of 0 and 0.5% (v/v), and temperatures of 52, 60, and 68degreesC. Starch yield was used as deciding factor to choose the best treatment. Lactic acid added in the steep solution improved the starch yield by an average of 5.6 percentage points. SO2 was more available to break down the structural protein network at 0.1% than at the 0.05% level. Starch-gluten separation was difficult at 68degreesC. The lactic acid and SO2 concentrations and steeping temperatures for better starch recovery were 0.5, 0.1, and 52degreesC, respectively. The Intermittent Milling and Dynamic Steeping (IMDS) process produced, on average, 1.4% more starch than the conventional 36- hr steeping process. Protein in starch, oil content in germ, and germ damage were used as quality factors. Total steep time can be reduced from 36 hr for conventional wet-milling to 8 hr for the IMDS process.

Accumulation of nutrients in sweet peppers cultivated in coconut fiber

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Crescimento e esporulação de duas espécies de arthrobotrys corda em diferentes meios de cultura e dois ambientes

The researches on the biological control of nematodes with nematophagous fungi has been intensified in recent years. The knowledge of the ecological conditions for the growth and sporulation of these fungi is a prerequisite for attainment of pure cultures needed to attend the demand for formulation of these organisms. With the objective to evaluate the micelial growth and sporulation of Arthrobotrys musiformis and A. oligospora in two environments (B.O.D at 25 +/- 1 degrees C and the environment of the Laboratory), 20 cultures media prepared with common materials found in the communities and industrialized media such as mycological agar, PDA and CMA were evaluated. The media were tested in Petri dishes, being the micelial growth of the fungi evaluated daily, during six days. The measured sporulation at the end of the experiment was done by estimation of the number of conidia/Petri dish. The experiment was carried out in a random design following a factorial arrangement of 20 x 2 x 2, corresponding to 20 media, two fungi and two environments, with five replicates. The variance analysis of the data evidenced significant statistical difference by the F Test, at 1% probability, among media x fungi x environment interaction. Fifty percent of the tested media provided the adequate micelial growth of A. musiformis and there was no statistical difference among them, namely: cassava meal (FM), sweet starch (PD), "corn meal agar" (CMA), oat in fine flakes (AFF), agar-water + dextrose (AA+D), mycological agar (AM), potato dextrose agar (BDA), meal of maize (FMI), flour of wheat (FT) and wheat for kibble (TK). In relation to A. oligospora, 75% of the tested media promoted the maximum growth of the fungus, which are: AFF, AM, FM, PD, CMA, AA+D, BDA, FT, TK, the water from the decoction of rice (AAZ), rice in grains (AZG), triturated rice (AZT), thread flour (FR), oats flour (FA), oats in thick flakes (AFG) and flour of maize (FU). In relation to the sporulation the media that had better role for A. musiformis, in decreasing order, were: FR, TK, AFG, BDA, FA, AFF, AM, FMI, AZT and FM, varying between 1,01 x 10(6) and 1,4 x 10(4) conidia/Petri dish. For the A. oligospora sporulation, the CMA medium provided the maximum level with an estimated average of 5,7 x 10(6) conidia/Petri dish. In the general, the best media for the micelial growth and sporulation of A. musiformis had also been the best for A. oligospora. However, some that had been the best for the A. oligospora did not had been efficient for the micelial growth or the sporulation of A. musiformis, indicating that the isolate of A. musiformis in case is more demanding than that A. oligospora one. The evidences from the study indicate that, in Jaboticabal, São Paulo state, the growth and the sporulation of these fungi do not demand special chambers. Some adaptations of an environment at the laboratory, enough to obliterate the light are sufficient.

Anaerobic biodigestion of pigs feces in the initial, growing and finishing stages fed with diets formulated with corn or sorghum

Objetivou-se avaliar a produção e a qualidade do biogás e do biofertilizante obtidos em biodigestores abastecidos com dejetos de suínos, nas fases inicial, crescimento e terminação, alimentados com dietas formuladas à base de milho ou sorgo. Foram utilizados 20 biodigestores de bancada, com tempo de retenção hidráulica de 30 dias, e cargas diárias que continham 4,0 a 6,0% de sólidos totais (ST) e 3,6 a 5,2% de sólidos voláteis (SV). Nos efluentes dos biodigestores, foram verificados teores médios de ST variando de 1,6 a 2,0% e de SV entre 1,2 e 1,6%. As reduções médias de ST foram de 57,7 a 64,7% e de SV de 61,7 a 69,0%, sendo que houve diferença somente na fase de terminação, na qual as maiores reduções médias foram para biodigestores abastecidos com dejetos de animais alimentados com dietas à base de milho. Nos biodigestores abastecidos com dejetos de animais em fase inicial e de crescimento, alimentados com dietas formuladas à base de milho, foram verificadas maiores produções médias de biogás e os maiores potenciais médios de produção de biogás. Os potenciais médios obtidos foram 0,033; 0,181; 0,685; 0,788 e 1,132 m³ por kg de afluente, estrume, ST adicionados, SV adicionados e SV reduzidos, respectivamente. Não foram verificadas diferenças quanto ao teor médio de metano no biogás entre dietas e fases. As concentrações médias dos nutrientes N, P, K, Ca, Mg, Na, Fe, Mn, Zn e Cu no afluente e efluente dos biodigestores variaram entre as dietas e fases.

Growth analysis of sweet pepper cultivated in coconut fiber in a greenhouse

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Intercropping corn and kudzu in a rotation system with soybean

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of temperature, leaf wetness, and rainfall on the production of Guignardia citricarpa ascospores and on back spot severity on sweet orange

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Susceptibility of fruits of the 'Valência' and 'Natal' sweet orange varieties to Guignardia citricarpa and the influence of the coexistence of healthy and symptomatic fruits

Em pomar de laranjeiras 'Valência' e 'Natal' avaliou-se a importância da presença de frutos sintomáticos da mancha preta citros (MPC) na severidade da doença nos frutos cítricos da safra subseqüente. Adicionalmente, avaliou-se o estádio de suscetibilidade dos frutos dessas variedades. Frutos foram protegidos com sacos de papel cristal a partir do estádio de 75% de pétalas caídas em outubro de 2000, até abril de 2001. Frutos foram expostos, em intervalos semanais, da 1ª à 24ª semana. Esse processo se deu tanto em plantas onde os frutos da safra remanescente foram previamente colhidos, como naquelas cujos frutos sintomáticos da safra remanescente permaneceram até a sua queda natural. Avaliou-se a severidade da doença usando uma escala de notas que variou de 0 (ausência de sintomas) a 6 (sintomas severos). Observou-se que para as duas variedades os conídios de Phyllosticta citricarpa, formados nas lesões dos frutos da safra remanescente, não provocaram incremento significativo na severidade da doença dos frutos da safra subseqüente. A proteção dos frutos até 10ª semana após a queda de pétalas não influenciou na quantidade final de lesões, indicando que as descargas de ascósporos que ocorreram a partir desse momento foram, provavelmente, responsáveis pela severidade da doença. Frutos que ficaram expostos entre a 20ª a 24ª semanas após a queda de 75% de pétalas mostraram-se sintomáticos, indicando que nesse estádio frutos encontravam-se suscetíveis ao patógeno.

Second generation European corn borer injury and Irish potato physiology, yield, and quality

European corn borer (ECB) [Ostrinia nubilalis (Hubner)] (Lepidoptera: Crambidae) is known to infest Irish potato (Solanum tuberosum L.) but only causes economic damage during the first generation in East Coast potato producing areas. However, in Nebraska, second generation ECB infest potato plants during the bulking period and may reduce yield and/or potato quality. Experiments were conducted in 2001, 2002, and 2003 to examine physiological and yield effects of second generation ECB injury to potato in Nebraska. Pike, Atlantic, and three Frito Lay proprietary varieties (FL1867, FL1879, and FL1833) were used. Experimental plots were infested with four ECB egg masses per plant to simulate ECB infestation by second-generation larvae; controls received no egg masses. Photosynthetic rates, tuber weights, tuber size grades, solids, and fry quality were measured. Potato plants with ECB infestation had significantly reduced photosynthetic rates on ECB-infested stems and on uninfested stems on the same plant when larvae were in the fifth instar. When insects were in the fourth instar, photosynthetic rates were reduced only on ECB-infested stems. In 2001, ECB infestation reduced the average mass of large tubers and increased the amount of small tubers in FL1867 and FL1879. In 2002, significant yield reductions were not observed. Across both years, ECB-infested plots produced fewer large (65- to 100-mm diam.) tubers than control plots. Other tuber properties and chip qualities were unaffected. This study indicates that second generation ECB infestation of approximately 30% infested plants results in economic loss for some chipping varieties and affects tuber bulking. In contrast to east coast growers, Midwest potato farmers must be concerned with second generation ECB.

Evaluation of fungicide applications to sweet orange at different flowering stages for control of postbloom fruit drop caused by Colletotrichum acutatum

Postbloom fruit drop (PFD), caused by Colletotrichum acutatum, produces blossom blight, fruit abscission and persistent calyces. in groves of Pera-Rio and Natal sweet orange located in Santa Cruz do Rio Pardo and Rincao, São Paulo, Brazil, four experiments were carried out to evaluate the effectiveness of fungicides sprayed alone or as mixtures, at different flowering stages for the control of PFD of citrus. The number of symptomatic flowers, the percentage of fruit set (FS), and the relationship between persistent calyces and total fruit weight per plant were evaluated. The fungicides carbendazim and folpet were sprayed at 0.50 ml and 1.25 ga.i. l(-1) of water, respectively, were superior by all the criteria to the other treatments. Carbendazim and folpet fungicides performed best when they were applied at the green bud through hollow ball stages. Difenoconazole, independent of application timing, was less effective by all criteria used. Application of mancozeb at 1.60 ga.i. l(-1) at the green bud stage followed by application of mancozeb in a tank mix with carbendazim or folpet at 1.0 ml and 1.25 g a.i. l(-1), respectively, during green bud bloom and hollow ball stages were effective for disease control. Carbendazim combined with 0.25% KNO3, reduced the number of persistent calyces and increased fruit production significantly. Applications must be made between green bud and hollow ball stages for best control. Applications only at hollow ball or open flower stages did not provide effective disease control. (C)2007 Elsevier Ltd. All rights reserved.