Nelson Raimundo Braga

Resistência de soja a Nezara viridula e Piezodorus guildinii em condições de campo

The soybean cultivars Parana. Vicoja and Santa Rosa, the line IAC 73-228 and the introductions PI 171451 and PI 229358,e were tsted in Campinas, State of Sao Paulo, Brazil, in relation to the stink bugs Nezara viridula L. and Piezodorus guildinii Westw. The line IAC 73-228 had the least percentage of damaged seed (48,l%) in the superior half of the plant, whereas Parana had the highest (96,8%). The introductions PI-171451 (71,1%) and PI 229358 (79,1%) had intermediate degrees of damaged seeds. This difference in damaged seeds could be due to actual resistance to the stink bugs, to resistance to Nematospora coryli transmitted by these insects or due to host evasion. It has been observed by DAUGHERTY et al. (1964) and LINK & COSTA (1974), that varieties with shorter period from flowering to harvest are less damaged by stink bugs and this would be a case of pseudo resistance called host evasion according to PAINTER (1951). There was a high positive correlation between percentage of seeds damaged and green stems at harvest. This feature could be used for field selection against these insects. There was positive significant correlation between damage and seed size. The seed size may be linked in some way to susceptibility to stink bugs. The damage was higher in the superior half of the plants than in the inferior.

Produtividade de genótipos de soja sob infestação da lagarta-da-soja e de percevejos

Three soybean experiments, one for each maturation group (early, semi-early, and medium), were installed in the field in Assis, State of São Paulo, during the 2003/2004 growing season to evaluate damage caused by Anticarsia gemmatalis (Hubn.) and by the soybean stink bug complex, Euschistus heros (F.), Piezodorus guildinii (West.), and Nezara viridula (L.). The experiments were installed again in 2004/2005, with the exception of the early cycle group. Defoliation caused by A. gemmatalis was evaluated by the percentage estimate of leaf area cut in the first year only, due to low caterpillar infestations in 2004/2005. All three stink bug species were present in both growing seasons. In 2003/2004, E. heros was predominant over the other two; in the following year, all three species occurred in similar numbers. The productivity criterion was adopted to evaluate stink bug damage. Based on both growing seasons and mainly considering productivity, a few lines could be selected within each maturation group for new field studies or for hybridizations in breeding programs. Among the early germplasm varieties, lines IAC 98-4540, IAC 98-4576, and IAC 98-3123 can be highlighted as promising; the latter also showed little defoliation by A. gemmatalis; in the semi-early group, IAC 98-4017, IAC 98-2663, and IAC 98-4250 were prominent, with steady productivity in both years; in the medium group, IAC 98-4136, the most productive, as well as IAC 98-4140 and IAC 98-4133, all with little defoliation, can be pointed out as promising.

Growth analysis of chickpea (Cicer arietinum L.)

An experiment to study the growing pattern of a chickpea variety, IAC-Marrocos, was carried out at the Monte Alegre Experimental Station, SP, during 1987 and 1988. The dry matter production of all parts of the plant, as well the leaf area index, were weekly evaluated. Exponential quadratic models of regression were adjusted to total dry matter, leaf dry matter and leaf area index, and a linear model to dry matter of grain. Based on the growth analysis it was concluded that the chickpea is a rustic eatable plant that can be recommended as an alternative winter crop for similar climatic conditions as those of the experiment.

Avaliação de danos de insetos e de severidade de oídio em genótipos de soja

Performance of 24 soybean lines from the breeding program of Instituto Agronomico (IAC) was evaluated under field conditions, as to attack of insects and incidence of powdery mildew. Three experiments, one for each maturity group (early-110, intermediate-120, and late-135 days), were carried out at the Experimental Station of Assis (2001/2002 and 2002/2003 growing seasons) and Experimental Station of Ribeirao Preto (2001/2002), both located in the State of Sao Paulo, Brazil. For all experiments, with ten treatments and six replicates, in randomized block design was adopted. Defoliation damage caused by Anticarsia gemmatalis Hubn. caterpillars was estimated visually, by the percentage of eaten leaf area (PAFC). Stink bugs [Piezodorus guildiniii (West.) and Euschistus heros (F.)] damage was evaluated by two criteria: percentage of foliar retention (PRF) and yield. The severity of powdery mildew (Microsphaera diffusa Cke. Pk.) was evaluated using a scale from 1 (no symptom) to 5 (more than 50% of leaves with symptoms). Considering the results of both locations, among the early maturity genotypes (110 days), the line IAC 98-4307 could be distinguished for the higher grain yield and low PRF under stink bug infestations. Regarding the genotypes of 120-day maturity group, the line IAC 98-2814 does not show foliar retention and presents higher grain yield, proving to be resistant to stink bugs; however this line is the most defoliated by caterpillars and presents more intense powdery mildew symptoms. Among the genotypes of 135-day maturity group, higher grain yield was observed in IAC 98-2856 under high or low stink bugs infestations, indicating tolerance to these insects, although it shows foliar retention under low stink bug infestation.

COMPORTAMENTO DE SEMENTES DE GRÃO-DE-BICO NA ARMAZENAGEM

Chickpea (Cicer arietinum L.) homogeneous seedlots, harvested in four sites in Sao Paulo State, Brazil, were initially evaluated for germination, vigor, moisture content and seed weigth. Thereafter, seedlots were submitted to storage, during two years, under the following conditions: (a) chamber at 12oC and 48% of relative humidity and (b) at room conditions. Germination and vigor tests (accelerated aging test, 42oC/48h), were applied at 6, 12, and 24 month intervals. All four seedlots showed similar water contents, ranging from 10.7 to 11.2%. However, seeds from Campinas were heavier than those harvested in the other localities. Seed germination and vigor decreased significantly with the increase of the storage period. Seedlots stored under controlled conditions presented higher germination and vigor values than those kept in the laboratory. Seeds harvested at Monte Alegre do Sul showed better germination and vigor than those from other places.

Insect damage and powdery mildew severity in soybean cultivars and lines

The use of soybean cultivars resistant to insects and diseases reduces the application of pesticides, decreasing production costs and promoting a sustainable agriculture. The damage of stink bugs and defoliators and the severity of powdery mildew (Microsphaera diffusa) in soybean of three maturity groups were evaluated under field conditions, at Taruma and Ribeirao Preto, State of Sao Paulo, Brazil. Three experiments, one for each group, were carried out in the 1999/2000 and 2000/2001 growing seasons. In 1999/2000, the disease occurred in Taruma; in that year, infestation of chrysomelids (Cerotoma sp. and Colaspis sp.) was observed in Ribeirao Preto. Low infestations of stink bugs occurred in both years and locations, but in Taruma, at the stage of plant maturation, the insect population exceeded the economic injury level. The severity of powdery mildew was evaluated using a scale varying from 1 (no symptom) to 5 (more than 50% of leaves with symptoms). Chrysomelid injuries were estimated by the percentage of leaf area removed, and stink bug damage was evaluated by the percentage of leaf retention (LRP) and yield. Within the early maturity group (110 days), IAC 94-2675 showed good yield levels, low LRP, and resistance to powdery mildew. In the genotypes of the 120-day maturity group, IAC 94-5, IAC 94-1172, IAC 94-1017, IAC 94-133, and IAC 94-745 presented good yield; the last two behaved as resistant to the disease. With regard to the genotypes of the 135-day maturity group, IAC 93-1564 and IAC 94-2939 showed good yield, low LRP, and resistance to powdery mildew.

Efeito da sucessão com leguminosas sob diferentes níveis de calagem no desenvolvimento e micorrização do trigo

Triticum aestivum was cropped in a quartz sand soil, in the region of Assis, State of Sao Paulo, Brazil, following soil that was kept fallow or soil that was previously cropped with Glycine max, Crotalaria paulina, Crotalaria juncea or Stizolobium aterrimum. All the treatments were submitted to three different doses of lime (0, 2 and 4 t/ha). The plants were evaluated in relation to mycorrhizae; shoot and root dry weight: grain production: and, phosphorus content in the flag leaf. The soil was analyzed in relation to phosphorus and mycorrhizal fungi sporos number. At 21-day plant emergence, the treatments that had received lime and one cropped with C. paulina showed higher percentage of: mycorrhizal colonization in the roots; shoot dry matter; and, grain production when compared to those that were cropped with G. max or kept fallow. The soil phosphorus content and the root fungi colonization did not reflect the nutritional status of wheat in relation to the element.

Épocas e espaçamento de semeadura em Crotalaria juncea L.

) COSTA, J. D. & AMARAL, E. Producao de sementes de Crotalaria juncea na presenca e na ausencia de insetos polinizadores. Rev. Agricultura, Piracicaba, 51:57-60, 1976. (*) : LOVADINI, L. A. C. & KIIHL, R. A. S. Autocompatibilidade em Crotalaria Juncea L. Rev. Agricultura, Piracicaba, 48:148, 1973. (

Planting date and row spacing effects upon Crotalaria juncea L.

) COSTA, J. D. & AMARAL, E. Producao de sementes de Crotalaria juncea na presenca e na ausencia de insetos polinizadores. Rev. Agricultura, Piracicaba, 51:57-60, 1976. (*) : LOVADINI, L. A. C. & KIIHL, R. A. S. Autocompatibilidade em Crotalaria Juncea L. Rev. Agricultura, Piracicaba, 48:148, 1973. (

Sowing date and row spacing effects on Crotalaria juncea L.

) COSTA, J. D. & AMARAL, E. Producao de sementes de Crotalaria juncea na presenca e na ausencia de insetos polinizadores. Rev. Agricultura, Piracicaba, 51:57-60, 1976. (*) : LOVADINI, L. A. C. & KIIHL, R. A. S. Autocompatibilidade em Crotalaria Juncea L. Rev. Agricultura, Piracicaba, 48:148, 1973. (