Sites and Time of Oviposition of Euphyllura phillyreae Foerster on Olive Trees and οon Phillyrea latifolia

The distribution of eggs of Euphyllura phillyreae Foerster (Homoptera: Aphalaridae) was recorded on twigs of olive trees and of Phillyrea latifolia L. in various locations of the Thessaloniki and Halkidiki prefectures of coastal northern Greece. On olive, the first eggs were observed in the last ten days of March and oviposition was intensified and became abundant only when the apical bud and the axillary leaf and flower buds started to swell. Eggs were laid mostly on swollen buds and on developing inflorescences. Oviposition preference was related to the stage of development of a bud and not to its location on the olive twig. On swollen leaf buds, most eggs were laid on the inner (upper) surface of the middle (second) pair of developing leaves, and fewer on the inner surface of the outer (first) pair and on the innermost (third) pair of leaves. On Phillyrea, eggs were deposited much earlier than on olive, on developing inflorescences. In choice and no-choice laboratory experiments, more eggs were laid on olive twigs bearing developing inflorescences, fewer eggs on twigs bearing only swollen terminal or axillary buds, and no eggs at all on twigs with only fully developed leaves of the previous year.

Leaf Area Distribution of Tomato Plants as Influenced by Polyethylene Mulch Surface Color

The influence of polyethylene (plastic) mulch surface color (white versus black) on leaf area distribution of tomato (Lycopersicon esculentum) was investigated in simulated planting beds at two sampling periods: an early sampling with relatively young plants that had been in the mulch treatment for 22 days and a late sampling with relatively mature plants that had been in the mulch treatments for 50 days. At the early sampling period, tomato plants grown with white mulch had more axillary leaves than plants in the black mulch, resulting in a greater axillary:main leaf area ratio for the plants with white mulch. Leaf area for total leaves (main + axillary) and plant biomass was unaffected by mulch surface color at the early sampling period. Tomato plants grown in black mulch at the early sampling period had significantly more area of main leaves partitioned to node 3, whereas plants grown in white mulch had more area of main leaves in nodes 8 and 9. Plants grown in the white mulch treatment had significantly more axillary leaf area at nodes 1, 2, and 3, whereas plants in black mulch had more axillary leaf area at node 6. At the later sampling period, most of the leaf area from both mulch treatments was recorded in the axillary leaves and there was no effect of mulch surface color on the amount of total leaf area partitioned to main, axillary, or total leaves; to the amount of biomass of the measured top growth; or to the nodal distribution of leaf area among main leaves or axillary leaves. Tomato plants in white mulch had significantly more fruit on plants at the later sampling period than plants in the black mulch. Mulch surface color also affected the plant light environment and soil temperatures. These results suggest that the polyethylene mulch surface color can induce changes in the plant microclimate and affect leaf area distribution of young tomato plants (as recorded at the early sampling) and fruiting of relatively more mature plants (as recorded at the later sampling).

Le développement du bourgeon axillaire du Manihot esculenta

The vegetative aerial apparatus of cassava consists of two kinds of axes: sylleptic and proleptic. After its determination, an axillary meristem may have either an advanced development, which characterizes a sylleptic axis, or a later development, which characterizes a proleptic axis. The morphological differences between the two categories of axes are easily explained as the result of differences in development. Proleptic development undergoes four stages: (i) determination, (ii) first latent period in the apical meristem, (iii) organogenesis, and (iv) second latency. The second and fourth stages do not occur in the advanced form of development. The first latent stage is due to a double precedency of both the upper part of the apical meristem and the axillary leaf primordium. The hypothesis of a control of the determination and the first latency of the axils from the whole apical meristem is discussed. The regulation of the two types of interruptions of development do not take place on the same scale and are probably not of the same type. Key words: axillary bud, stem, development, cassava, proleptic, sylleptic.

Tomato Leaf Development and Distribution as Influenced by Leaf Removal and Decapitation

The influence of leaf removal and decapitation (removal of apical bud and top two nodes) of determinate tomato (Lycopersicon esculentum Mill cv. Mountain Pride) plants on canopy development was investigated. Leaf removal and decapitation influenced subsequent leaf development and distribution, and early fruiting of greenhouse-grown tomato plants. `Removal of young axillary leaves increased the size of main (true) leaves in the middle and upper nodes, increased the number of nodes, and increased the number of early fruit produced. Removal of main leaves reduced axillary leaf development at nodes 5 and 9. Decapitation increased axillary leaf development in the middle and upper nodes and delayed early fruit production. These results suggest that cultural practices of tomatoes that remove leaves or apical buds to influence fruiting also affect canopy leaf development and distribution.