Estádios fenológicos da macieira nas cultivares Gala, Fuji e Golden Delicious

Os estádios fenológicos da macieira podem ser alterados pelas condições climáticas, sendo a temperatura um dos principaisfatores. O conhecimento da duração dos estádios fenológicos poderá contribuir para o planejamento das diversas atividades do pomar. Otempo médio entre os diferentes estádios fenológicos das cultivares de macieira Gala, Fuji e Golden Delicious e sua relação com astemperaturas foram determinados por um período de cinco anos. Com base nos dados fenológicos e nas temperaturas foi calculado osomatório dos graus-dia (GD) nos diferentes estádios. A duração destes variou de acordo com a cultivar e o ano. Observou-se atendência de que, quanto maior a quantidade de unidades de frio recebida durante a dormência, menor o tempo médio para ocorrera brotação, não havendo correlação com os graus-dia. Porém, a maior amplitude dos estádios fenológicos corresponde a mais graus-dia. Aduração acumulada dos estádios fenológicos é muito semelhante nas três cultivares, dependendo sua variação das condições climáticas

Necessidades térmicas para indução da brotação de diferentes cultivares de macieira

The heat requirements for bud burst of six apple cultivars were evaluated. Shoots with 20 to 25cmlength were submitted to 1,150 cold units. After this treatment, shoots were divided in single bud cuttings and treated at different temperatures (5, 10, 15, 20 and 25oC). The mean time of budbreak (MTB), development index, base temperature and degree-days for budbreak for each cultivar was calculated. The increase of temperature after chilling reduced the MTB in all cultivars. The base temperature to calculate the degree-days varied among cultivars, but has not relation with chilling requirement. The development index improves with temperature increase. The heat requirement is stable at temperatures between 10 and 25oC. The heat requirement is independent of the chilling requirement.O objetivo deste trabalho foi avaliar as exigências térmicas para a brotação de seis cultivares de macieira, duas comerciais (Gala e Fuji) e quatro com potencial para produção comercial no Sul do Brasil (Condessa, Imperatriz, Daiane e Baronesa). Ramos medindo de 20 a 25cm de comprimento foram submetidos a 1.150 unidades de frio e, em seguida, a temperaturas de 5, 10, 15, 20 e 25oC, em câmara de crescimento, para ser avaliado o número de dias para brotação e calculado o índice de desenvolvimento, a temperatura base e osgraus-dia necessários para a brotação. O aumento de temperaturas, de 5 a 25oC, após a superação da necessidade em frio reduz o número de dias para brotação, independentemente da cultivar. A temperatura-base para cálculo dos graus-dia varia com a cultivar, porém não apresenta relação com as necessidades de frio da cultivar. O índice de desenvolvimento aumenta com a temperatura após a superação da dormência. A exigência de calor para a brotação é estável nas temperaturas entre 10 e 25oC. A necessidade de calor independe da necessidade de frio das cultivares

Capacité de croissance de la partie aérienne du fraisier (Fragaria X ananassa Duch.) sous conditions naturelles et traitement au froid en automne, et sous longue conservation au froid : évaluation de la repiration et de la chaleur métabolique comme marqueurs de capacité de croissance.

Economical constraints require increasing technicality in horticulture, even more than in other areas of plant production. Strawberry plants began to be raised under artificial conditions long ago. Empirical base for production management was sufficient for long time. However, management and artificial conditions requires more and more to be based on accurate knowledge in plant ecophysiology. Studies allowed to design a test of growth capacity of strawberry buds, inspired by the tests designed for tree buds; we used it as reference test. Nevertheless, it involves methods too heavy to be really useful for the nurserymen. Other parameters easier to be measured seemed to be relevant candidate markers, but only preliminary studies have been done. The metabolic heat (Q) and the respiration flux (RCO2) are examples of these parameters; we tested them through the values they gave when measured before and after 20°C acclimation of the plants. Our results showed that Q and RCO2 measured before acclimation could not be relevant markers of the bud growth capacity; indeed, their values were closely related to the mean temperature that the plants underwent during the some days before measurement. On the other hand the difference between the values measured before and after 20°C acclimation during 48 hours, appeared to be an interesting marker, giving values much more rapidly than do classical tests. However, acclimation and microcalorimetric measurements conditions are still to be improved; also the repetitions numbers should be increased. The water content changes were closely parallel to the Q and RCO2 ones; it could replace these parameters and be an interesting tool for the nurserymen.Peut être plus encore que dans d'autres secteurs de production végétale, en horticulture les contraintes économiques imposent une technicité croissante. L'artificialisation des productions de plants de fraisiers a commencé depuis longtemps. L'empirisme a permis de mettre au point des pratiques qui ont longtemps suffi. Mais, cette artificialisation demande de plus en plus une maîtrise raisonnée qui doit reposer sur des connaissances précises de l'écophysiologie des plants. D'autre part, des recherches ont permis de définir un test de capacité de croissance des bourgeons, inspiré de ceux faits sur les bourgeons des arbres, et nous l'avons mis en oeuvre comme référence. Cependant, en particulier au niveau de l'intérêt pour les professionnels, ce test implique des méthodes encore trop lourdes. D'autres marqueurs plus faciles à mesurer semblaient des candidats valables, mais seules des études préliminaires ont été faites.C'est le cas du flux de chaleur métabolique (Q) et du flux de respiration (RCO2) que nous avons testé en mesure immédiate et après acclimatation des plants à 20°C. Nos résultats indiquent que Q et RCO2 en mesure immédiate ne peuvent constituer de bons marqueurs de capacité de croissance, car leurs valeurs sont fortement corrélées aux températures moyennes subies par les plants dans les quelques jours précédant la mesure. En revanche, le différentiel obtenu entre mesure immédiate et mesure réalisée après acclimatation pendant 48 h à 20° C est potentiellement un marqueur intéressant, d'obtention beaucuop plus rapide que les résultats des tests classiques. Il faudra cependant optimiser les conditions de réalisation de l'acclimatation et des mesures microcalorimétriques et augmenter sensiblement le nombre de répétitions des mesures. L'utilisation du paramètre humidité pondérale, dont la dynamique d'évolution est très proche de celles de Q et RCO2, comme substitutif à ces paramètres peut constituer un autre outil intéressant les producteurs de plant

Capacité de croissance de la partie aérienne du fraisier (Fragaria X ananassa Duch.) sous conditions naturelles et traitement au froid en automne, et sous longue conservation au froid (évaluation de la respiration et de la chaleur métabolique comme marqueurs de capacité de croissance)

CLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF

Efeito da intensidade do frio no tempo e percentagem de gemas brotadas em macieira Effect of the cold intensity in time and percentage of shoot buds in apple trees

A macieira necessita de períodos de baixas temperaturas (4º a 10ºC) no outono e inverno, caso contrário a planta continuará em dormência ou apresentará uma brotação e floração irregular. Sem a ocorrência de baixas temperaturas no outono e inverno, as gemas da macieira continuam em dormência por um maior período. Para mensurar a quantidade de frio necessária para superar a dormência, o método utilizado foi o número de unidades de frio baseado no Modelo Carolina do Norte Modificado. Estacas de 20 a 25 cm de comprimento e estacas de nós isolados receberam zero, 530, 1060 e 1590 unidades de frio durante a dormência. As cultivares testadas foram 'Condessa', 'Baronesa', 'Daiane', 'Imperatriz', 'Gala' e 'Fuji'. As cultivares se diferenciaram quanto ao número de dias para a brotação das gemas, ocorrendo o menor tempo para a brotação quando receberam 1590 unidades de frio, para todas as cultivares, mostrando que há uma relação entre o tempo médio da brotação e a profundidade da dormência. A porcentagem de brotação das gemas foi maior quando as estacas foram submetidas a 1590 unidades de frio, sendo que a cultivar Condessa apresentou o maior percentual de brotação, confirmando as referências que indicam ser esta a cultivar de menor exigência em frio, dentre as estudadas.<br>Apple tree demands periods of low temperatures (4ºC to 10ºC) during autumn and winter, otherwise the tree will keep under dormancy or will present an irregular shooting and blooming. Without low temperatures during autumn and winter, apple tree buds keep under dormancy during a longer period and present an irregular shooting and blooming. In order to measure the quantity of cold needed to subject the dormancy, it was used the method of number of cold unities according to the Modified Model of the North Carolina. In stakes with length from 20cm to 25cm, and in stakes of isolated knots, which received from zero to 530, 1,060 and 1,590 cold unities during the dormancy. Tried cultivars were Condensa, Baronesa, Daiane, Imperatriz, Gala and Fuji. Cultivars differed themselves on the number of days for the shooting of the buds, taking place the minor time for shooting when they were subjected to 1,590 cold unities, for all the cultivars, what showed that there's a tie between the average time of the shooting and the deepth of the dormancy. The percentage of shoot buds was also larger when the stakes were exposed to 1,590 cold unities, being Condensa the cultivar that showed the largest percentage of shooting, what confirms that it is really, among the studied cultivars, that of minor demand in cold

Physiological and biochemical evolution of peach leaf buds during dormancy course under two contrasted temperature patterns

Budbreak anomalies in temperate fruit trees grown under mild conditions have often been described. However, only few authors approached the physiological evolution of leaf buds all along the dormancy period according to the temperature pattern. The aim of this study was to characterize the evolution of peach leaf bud dormancy through some physiological and biochemical parameters under temperate winter conditions and under total cold deprivation after the endodormancy onset. Two treatments were applied in peach trees cv. Redhaven: (i)Regular Chilling Amounts – RCA and (ii) Total Chilling Deprivation – TCD. Buds were sampled periodically from different parts of the stem(terminal, medium and basal ones). We recorded the evolution of: carbohydrate concentrations (glucose, fructose, sucrose, sorbitol and starch), respiration rate, water contents and energy metabolism (ATP and ADP ratio). The dynamics of these parameters were compared and correlated with dormancy evolution (“one node cuttings” test) and budbreak patterns in planta. The endodormancy intensity of terminal buds was significantly lower than those of median and basal buds in early October. Under RCA treatment, this gradient faded and the bud endodormancy release was completed at the same time in all positions along the stem. Thereafter, the “cuttings” test indicated that terminal buds grew slightly faster than median and basal buds, and, consistently, budbreak in planta started with the terminals buds, followed by the medians and then by the basal ones. The carbohydrate contents showed a transitory change only when the buds began to grow after the endodormancy was released under RCA. Respiration, water content and ATP/ADP changed dynamics only under RCA and only after the end of the endodormancy (their respective changes were very parallel). The dynamics of none of the tested parameters could be related with the endodormancy dynamics, but respiration, water content and ATP/ADP could be consistent markers of the actual bud growth before bud break (in this respect, ATP/ADP could not show differences between the terminal and axillary buds while respiration and water content could)