Experiência de apoio à associação de agricultores familiares no Alto Moju, PA.

bitstream/item/18917/1/Doc-294.pdfVersão eletrônica. 1ª impressão: 2009

Starch accumulation and agronomical performance of Syrah under winter cycle: responses to pruning and ethephon management

In the Brazilian Southeast, 'Syrah' grape harvested during the winter reaches better quality index than those from summer harvest. However, the management of annual double pruning to produce two grapevine growth cycles (vegetative cycle: spring – summer; reproductive cycle: autumn – winter) has increased the vineyard production costs and the vine reserve accumulation can be compromised. This study had two main objectives to improve the winter cultivation: i) to validate single pruning carried out only in summer (February) (experiment 1); to increase the reserve accumulation by ethephon (ethrel) sprayed two months before yield pruning (experiment 2). Both experiments were carried out in south of Minas Gerais State using three years old field-grown 'Syrah' grapevines grafted onto '1103 Paulsen' and trained in a vertical shoot position. The results from experiment 1 showed that grapevines pruned in summer also need to be pruned during the winter after grape harvest to avoid bud infertility during the following autumn-winter season. Single pruning reduced the starch contents in shoots, trunks and roots sampled before yield pruning and the commercial grape harvest was completely unavailable due to unfruitful shoots. On the other hand, the autumn-winter cycle was improved by ethephon sprayed in the previous vegetative growing cycle (summer cycle). During the autumn-winter cycle, sprayed grapevines showed higher starch content in trunks, high vegetative vigor and the yield and grape quality were not negatively affected

Effect of pruning strategy on 'Syrah' bud necrosis and fruitfulness in Brazilian subtropical Southeast

The change of wine grape harvest from wet season (summer) to dry season (winter) by changing the pruning management has improved quality of wines produced in the Brazilian Southeast. However, the vines need to be spur pruned twice a year, i.e. with a 1st pruning in August (winter pruning) for a vegetative cycle during the hot and wet summer, and a 2nd pruning in January (summer pruning) for a productive cycle during the cold and dry season. This double pruning strategy is made necessary by the fact that latent buds developed during the dry season cycle are not fruitful to support a productive cycle in the following year. This histological study, performed in the South of Minas Gerais State (Brazil), showed that annual single pruning done in the wet season (in January) displayed a high rate of necrosis on primary and secondary buds (bud necrosis – BN). In April, 99 days after summer pruning (DASP), the rates of BN were 40 % and 50 % at basal and apical node positions, respectively, reaching 80 % of BN in December (322 DASP). As a consequence of BN, bud potential fertility was drastically reduced from 0.5 inflorescence primordial (IP) per bud (in July) to 0.06 (in December) and bud burst in the next cycle from secondary and tertiary bud axes. Vines managed by double pruning system (submitted to summer and winter pruning) displayed a much higher fruitfulness potential, i.e. 1.46 IP per bud in December (112 days after winter pruning) and limited BN occurrence (20 %). On single pruned vines, we also observed a significant decrease of starch content in canes, trunks and roots. Internal bud anatomy showed that a random cell breakdown started 70 days DASP. At 211 DASP, all buds showed a large starch granule concentration, raphides and crystals of calcium oxalate inside idioblasts of leaf primordia and also in cortical parenchyma of the vegetative axis. The bud starch content was increased and a positive correlation between necrosis and starch accumulation was observed. The impact of carbohydrate availability on bud necrosis development was discussed. This study showed that the necrosis development towards secondary and tertiary axis of the dry season buds is the main reason of unfruitfulness in the vineyards managed by single pruning in the wet season, making the double pruning compulsory

As catadoras de mangaba em defesa dos seus modos de vida.

bitstream/item/141804/1/DOC-192.pd