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The spatial variability of leaf wetness duration (LWD) was evaluated in four different height-structure crop canopies: apple, coffee, maize, and grape. LWD measurements were made using painted flat plate, printed-circuit wetness sensors deployed in different positions above and inside the crops, with inclination angles ranging from 30 to 45 degrees. For apple trees, the sensors were installed in 12 east-west positions: 4 at each of the top (3.3 m), middle (2.1 m), and bottom (1.1 m) levels. For young coffee plants (80 cm tall), four sensors were installed close to the leaves at heights of 20, 40, 60, and 80 cm. For the maize and grape crops, LWD sensors were installed in two positions, one just below the canopy top and another inside the canopy. Adjacent to each experiment, LWD was measured above nearby mowed turfgrass with the same kind of flat plate sensor, deployed at 30 cm and between 30 and 45 degrees. We found average LWD varied by canopy position for apple and maize (P<0.05). In these cases, LWD was longer at the top, particularly when dew was the source of wetness. For grapes, cultivated in a hedgerow system and for young coffee plants, average LWD did not differ between the top and inside the canopy. The comparison by geometric mean regression analysis between crop and turfgrass LWD measurements showed that sensors at 30 cm over turfgrass provided quite accurate estimates of LWD at the top of the crops, despite large differences in crop height and structure, but poorer estimates for wetness within leaf canopies.

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Avaliaram-se dados fenológicos da videira 'Niagara Rosada' em diferentes regiões do Estado de São Paulo para as seguintes épocas de poda: 15/7; 1/8; 15/8 e 1/9, durante os anos agrícolas de 1989/90 e 1990/91, com o objetivo de avaliar o comportamento fenológico e as necessidades térmicas da cultura. A duração das fases fenológicas variou em função do local e da época de poda. O ciclo total durou de 116 dias para a época de poda 1º/9, em Tietê e Mococa, até 199 dias para a poda de 15/7 em São Roque. A temperatura-base para a fase brotação-maturação foi de 12°C e a necessidade térmica (graus-dia) média, de 1.330, variando de 1.248 para Jundiaí a 1.386 para São Roque. A data de poda não influenciou o valor da necessidade térmica num mesmo local.