Information on factors influencing the rate and duration of seed growth is needed to understand completely yield production. This study was undertaken to determine the relationship of seed size and the timing of pod development to the rate and duration of seed growth in soybeans (Glycine max (L.) Merrill). Field studies were conducted for 2 years (1974‐75) on a Maury silt loam soil (Typic Paleudults) utilizing five cultivars of varying seed size: ‘Kanrich’, 234 mg/seed; ‘Williams’, 171 mg/seed; ‘Cutler 71’, 165 mg/seed; ‘Custer’, 129 mg/seed; and ‘Essex’, 114 mg/seed. Each year the rate of dry matter accumulation in the seed was measured on the first and the last pods to develop on each cultivar. Kanrich had the highest seed growth rate (7.96 mg seed−1 day−1); Essex the lowest rate (3.64 mg seed”1 day1), and the other cultivars had rates intermediate between Kanrich and Essex. Seed growth rates were relatively constant across the early and late pods. The duration of the effective filling period (EFP) was less for the late pods on the indeterminate cultivars (Kanrich, Williams, Cutler 71, and Custer), and this resulted in slightly smaller seed. There was no difference in the length of the EFP among the five cultivars used. Air temperatures during the filling period were lower in 1974 than in 1975, and the low temperatures were associated with low seed growth rates, a long EFP and large seed. These data suggest that the rate of seed growth is partially determined by the genetic makeup of the seed. The direct relationship between seed growth rates and seed size provides an explanation of the negative correlations frequently observed between seed size and the number of seed produced by the plant.

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Estima:es of species density,percentagevegetativecover, biomass, andsawgrtcss (Cfadium jamaicense) height were made in Tall Sawgrass, Medium Saw'grass, and Wet Prairie communities in the SE portion of Water Conservation Area 3A (3A), the SW portion of Water Conservation Area 3B (3B), the NW portion of Northeast Shark Slough (NSS), mad the NE Ixmion of Everglades National Park (ENP) during dry season and wet season sampling periods in 1986 and 1987. We summarized the history of water management and hydroperiod manipulation in the study area. Wet Prairie had the deepest water of the three plant communities studied, while 3A had deepest water and longegt hydroperiod of the hmr are~. Generally, the greatest species density occurred in NSS, where water was shallowest. Individua] sawgrass plants and their basal tussocks were taller in 3A than in the other three areas, which may make plants in 3A more susceptible to damage by airboats ,and fire. Cover and biomass of sawgrass fluctuated more between sampling periods than among managemerit areas, which rendered lower measurements in Tall Sawgrass in 3FI non-significant.Species composition of Wet Prairies, particularly in 3A where Rhynchospora spp. were absent, and Ny'rnphaea odorata was dominant, resembled aquatic sloughs. The low species density in the study area may be related to rapid fluctuations in water levels that could drown slow-growing plants, and to infrequent dry periods that preclude seed germination. Species richness was low, compared with other Everglades plant community studies. No annual emergent plants were encountered.

Relative pi8nt abund8nce, anopy cover, 8nd aerial biomrss of shrubs on a poor condition, fi8twoods range in south Florid8 were me8sured before, 1, md 3 yr 8fter II singie p8ss of 8 roller chopper or web plow when soils were dry (M8y 1981) 8nd when soils were srrtur8ted (September 1981). Aeri8i biomrurs of herb8ceoun species wm measured 8t the post-tre8tment sunpie d8tes. Abundance of s8w-palmetto (Screnoa repem (Bartr.) Smaii) plants, the dominant shrub, was reduced 70% by web plowing comp8red to 25% by roller chopping. Reductions of scow-p8hnetto ernopy cover 8nd aerirl biomass 8iso were gre8ter on web-plowed th8n on roller-chopped plots. Runner o8k (Quercus minima (sug.) Snmii) was the only other shrub which h8d more th8n 5% anopy cover before treatment. Both types of mech8nic8i treatments controlled runner o8k by 8pproxinuteiy 50% However, responses of runner 08k abundmce, canopy cover, and 8eri8i bionmss were not significantly diff-ent between roller chop 8nd web plow treatments.