Paulo Boller Gallo

Genotype-environment interaction and phenotypic stability for girth growth and rubber yield of Hevea clones in São Paulo State, Brazil

The best-yielding, best vigour and most stable Hevea clones are identified by growing clones in different environments. However, research on the stability in Hevea brasiliensis (Willd. Adr. ex Juss.) Muell.-Arg. is scarce. The objectives of this work were to assess genotype-environment interaction and determine stable genotypes. Stability analysis were performed on results for girth growth and rubber yield of seven clones from five comparative trials conducted over 10 years (girth growth) and four years (rubber yield) in Sao Paulo State, Brazil. Stability was estimated using the Eberhart and Russell (1966) method. Year by location and location variability were the dominant sources of interactions. The stability analysis identified GT 1 and IAN 873 as the most stable clones for girth growth and rubber yield respectively since their regression coefficients were almost the unity (b = 1) and they had one of the lowest deviations from regressions (S2di). Their coefficient of determination (R2) was as high as 89.5% and 89.8% confirming their stability. In contrast, clones such as PB 235, PR 261, and RRIM 701 for girth growth and clones such as GT 1 for rubber yield with regression coefficients greater than one were regarded as sensitive to environment changes.

Desempenho de híbridos top crosses de linhagens S3 de milho em três locais do Estado de São Paulo

The present work aimed to evaluate the performance end high parent heterosis of 27 hybrids of partially endogamic lines (S3) obtained from commercial hybrids, using top cross squemes with testers (IA 33). Also, the general combining ability (GCA) of the lines was evaluated. The 27 top cross hybrids, two commercial checks and the tester were evaluated by complete block design with three replications, in two years (2005/2006 e 2006/2007), and three locations (Campinas, Mococa and Palmital) of Sao Paulo State. The evaluated traits were: plant height (AP), ear height (AE), percentage of broken and loged plant (AC+Q), ear yield (PE) and grain yield corrected of 14% moisture (PG). Top cross hybrids of high yield performance that outperformed or did not differ from the commercial check were observed. Therefore top cross hybrids with high yield performance and with advantage of small production cost were identified. Also line S3 with high value of GCA were observed.

Produtividade de cultivares de arroz irrigado resultanteda aplicação de doses de nitrogênio

The objective of this study was to evaluate the response of three rice cultivars to N fertilizers under irrigated conditions. Two field experiments were carried out in Mococa, SP, in 2000/01 and 2001/02. Rates of N (0, 90, 180, and 270 kg ha-1) were applied in the main plots and seedlings of three rice cultivars (IAC 101, IAC 103, and EPAGRI 109) were transplanted into the subplots. Nitrogen, as urea, was split in three applications: at transplantation, 20 and 40 days later. Except for the number of spiklets per panicle, yield components did not respond to N rates, although they varied for the different plant genotypes. IAC 103 presented the higher value for panicle fertility index and number of panicles per area, and the lower plant height, compared to IAC 101 and EPAGRI 109. Number of plants per area was the yield component most closely related with grain yield. Responses to N varied with the genotype. The highest rate of N to maximize economic return (218 kg/ha N and 6790 kg/ha grain yield) was observed for IAC 103. The corresponding rates for the other genotypes were 161 (EPAGRI 109) and 179 kg/ha N (IAC 101). These rates are higher than those currently recommended for waterlogged rice in Brazil.

Heterose e seus componentes em híbridos de populações F2 de milho

The potential of 28 hybrids maize F 2 population, obtained from a complete diallel among eight F 2 populations, along with the eight parental F 2 populations and two commercial controls were evaluated for agronomic traits, heterosis and its compo - nents. The experiments were developed in 2008/09, in Campinas, Mococa and Palmital, Sao Paulo State, Brazil. The experi - mental design was in randomized blocks, with three replications. The agronomic traits male flowering, ear height and grain yield were evaluated. The grain yield was adjusted to 14% of moisture. Individual and grouped variance analyses were made considering the fixed model, with the means being compared by the Tukey test. The Gardner and Eberhart (1966) model was used in the diallel analysis. It was observed that the effect of heterosis and its components were highly significant. Consider - ing the grain yield, populations F 2 AG8060, F 2 Fort, F 2 A2555 are promising in hybrid combinations, with high values of parental heterosis. The population F 2 DAS2B710 had the greatest parental heterosis effects. There was heterosis manifestation for grain yield, mainly for hybrid F 2 A2555 x F 2 Fort. It was confirmed the potential of F 2 population hybrids as an alternative to the commercial maize production with medium to low technological input.

Temperatura do ar em sistemas de produção de café arábica em monocultivo e arborizados com seringueira e coqueiro-anão na região de Mococa, SP

The technique of arborized coffee crops attemp to minimize the extreme meteorological conditions improving the crop development and yield. This work aimed to characterize the air temperature in arborized systems compared to unshaded cultivation. Evaluations were accomplished in a field experiment, implanted in 1999 at Mococa, one of the most important coffee producing areas at State of Sao Paulo, Brazil. The experimental plot had 1600 m 2 , where the coffee plants, cv. Icatu Vermelho IAC 4045, were cultivated in unshaded and arborized systems with rubber tree (16x16m) and dwarf coconut palm (8X8m). The air temperature measurements were made during 2006/07 and 2007/08 crop production years. The treatment with rubber tree reduced the daily maximum air temperature up to 3 °C, especially during summer and spring seasons. In cloudy days there were no differences among treatments with rubber tree and dwarf coconut palm tree and unshaded system. Higher values of daily air temperature amplitude were observed in unshaded coffee treatment. The arborized systems minimize the extreme low temperature effect as they raise the minimum air temperature up to 2 o C.