ESTIMATION OF ARTIFICIAL PRECIPITATION ENHANCEMENT RESOURCE CONDITION AND CLOUD SEEDING POTENTIAL BY GROUND-BASED REMOTE SENSING DATA

In this paper,the data of continuous atmospheric vertical integral vapour and liquid water content during April-June of 1992-1994 obtained by a ground-based dual-channel microwave radiometer are used to analyse the statistical characteristics of atmospheric vapour and liquid water content,and the relative distribution characteristics of vapour and liquid water content in cloudy atmosphere,the correlative relation of integral liquid water content L and ground precipitation intensity I.and precipitation transform rate of precipitation system.Finally,the weather modification condition of precipitus stratiform clouds and seeding potential is analyzed and discussed.

Seed Potential of Ruminants Organic Manures in Sahelian Agro-Pastoral Systems

In degraded Sahelian agro-systems, livestock manures increase agricultural production and ensure natural regeneration through their selective seed potential. Yet, this seed potential that contributes to species dissemination is still poorly known. This study aimed to determine the seed potential of different livestock ruminant manures. To this end, cattle (Bos indicus), goat (Capra hircus) and sheep (Ovis aries) manures were collected in 45 distinct enclosures in the Sahelian zone of Burkina Faso following the three seasonal periods of the year. A total of 36 species in 13 families and 26 genera was identified in the coarse fraction of the three type of manure. The most abundant seeds in the manure are those of Fabaceae-mimosoideae, Fabaceae-caesalpinoideae, Rhamnaceae and Balanitaceae. The results showed that the contribution of goats to the total seed potential was 61% against 36% for sheep and 3% for cattle. The average number of seeds was 205 seeds/Kg of manure for goats, 125 seeds/Kg for sheep and 11 seeds/Kg for cattle. Depending on the collection period, the cold-dry season contributed 70% to the total annual seed potential against 22% of the hot-dry season and 8% for the rainy season. Following the species functional traits, goat spread more seeds of woody indehiscent pods (barochores species) containing one, 4 to 10 seeds with hard cores and integuments. Sheep spread more seeds of annual legumes having dehiscent pods (autochores) and more than 10 seeds. The most abundant seeds in the manure are those of agroforestry (Vachellia nilotica, Faidherbia albida, Piliostigma reticulatum), ruderal (Ipomoea eriocarpa) or invasive (Senna obtusifolia) species. The most frequently (RI Dactyloctenium aegyptium, Eleusine indica, Corchorus tridens, Sporobolus festivus and Ipomoea eriocarpa. Taxonomic and functional characteristics of the seed potential of ruminants manures shape the regeneration traits of agro-ecosystems through selective seed dissemination.

Seed and Wasp Production in the Mutualism of Figs and Fig Wasps

Figs (Moracea: Ficus) and fig wasps (Hymenoptera: Chlocloids: Agaonideae) depend on each other to complete their reproduction. Monoecious fig species and their pollinating wasps are in conflict over the use of fig ovaries which can either produce one seed or one wasp. From observation on Ficus virens Ait., we showed that female flowers with outer layer of ovaries (near to the wall of syconium) had no significant difference from that with inner and interval layer of ovaries (near to the syconium cavity), in which most seeds and wasps were produced. This meant that fig tree provided the same potential resource for seed and wasps production. Observation indicated that there was usually only one foundress in syconium at female flower phase and no com- petition pollinators. Measurement of the style length of female flowers and the ovipositor of pollinators indicated that most ovaries could be reached by pollinator’s ovipositor. However, at the male flower phase, production of seeds was significantly more than that of wasps including non-pollinating wasps but there was no significant difference between seed and pollinating wasp production when without non-pollinating wasps produced. This result indicated that non-pollinating wasps competed ovaries not with seeds but with pollinating wasps for ovipositing. Bagged experiment showed that the sampling fig species was not self-sterile which was important for figs and wasps to survive bad season. Seed production in self-pollinated figs was not significantly different from total wasps in- cluding non-pollinating ones. This might be related with the weaker competition among wasps since bagged figs were not easy to reach by wasps from outside.