Frank G. Martin’s research while affiliated with University of Florida and other places

Field experiments were conducted in 1997 and 1998 to evaluate the effect of mowing followed by hexazinone for West Indian dropseed/giant smutgrass (Sporobolus indicus var. pyramidalis) (hereafter referred to as dropseed) control. The experimental design was a split plot, with mowing (nomnowed [mature] and 35-cm regrowth) as the whole plot and hexazinone rate (0.0 [control], 0.56, 0.84, 1.12, 1.40, and 1.68 kg ai/ha) as the subplot treatments. The application of 0.84 kg/ha hexazinone provided 94 and 81% dropseed control, 365 d after treatment (DAT) during 1997 and 1998, respectively. Increasing application rate to 1.12 kg/ha hexazinone provided 87 and 88% dropseed control, 365 DAT during 1997 and 1998, respectively. Both the 0.84 and 1.12 kg/ha rates provided the same average control (87.5%); however, the 1.12 kg/ha rate provided consistent control over years. Mowing dropseed, followed by hexazinone application at 35-cm regrowth, provided no additional control when compared with no mowing treatments. Rates of hexazinone at 1.40 and 1.68 kg/ha caused phytotoxicity to bahiagrass and increased bare soil surface area, especially 90 and 120 DAT. Phytotoxic effect on bahiagrass and on bare soil decreased 365 DAT, resulting in 75 to 80% total forage cover. Concentration and yield of total nonstructural carbohydrates were significantly lower for the mowed 35-cm regrowth treatment than for the nonmowed plants; however, even in its weakened condition this reduction had no effect on dropseed control.

Effects of season and fertilization on seed production were investigated for a central Florida ecotype of Leavenworth's coreopsis (Coreopsis leavenworthii Torr. & A. Gray) grown in containers. Since container-grown ecotypes of native, herbaceous species are frequently grown using nutrient regimes lower than those for production of typical garden plants, Osmocote 18N–2.6P–10K (18–6–12;8–9 month formulation) was incorporated into the soilless substrate at one-half the low, low, and medium label rates for container-grown herbaceous plants [1.8, 3.6, and 5.4 kg/m3 (3.0, 6.0, and 9.0 lb/yd3], respectively. Seed were harvested from mature heads (capitulescences) in late May to mid-July, and then again from late July to late October after plants had been cut back and reflowered. Seed yield and quality were greatest for the May–July harvest. Averaged over fertilizer rate, there were 3-fold more filled seed per mature head for the May–July harvest than during July–October. Mature head production was most responsive to increases in fertilizer rate during May–July. Percent germination of viable seed was nearly 90% or more for both harvests, but there were more viable seed for May–July than for July–October (75 vs. 57%). Seed also ripened much more uniformly during May–July then during July–October. Based on these conditions and results, the best time to harvest seed was from May to early July.

One method of obtaining seeds of native plants may be to let seeds fall to the soil surface and collect them by vacuuming. We evaluated this method by comparing plants that germinated from material vacuumed after fire with plants that germinated from seeds found in cores taken from the top 25 mm (1 in) of soil in a Florida flatwoods plant community before and after fire. A total of 76 species were identified in cores, of which 66 species were found before, and 60 species after, fire. No differences attributable to fire were found for seed density (3261 seeds/m2 [2740/yd2]) or concentration in cores (282 seeds/kg [128/lb]). Vacuumed material contained seeds of 58 species (54 in common with cores) with a density of 170 seeds/m2 [142/yd2] and a concentration of 451 seeds/kg (204/lb). Species correlations between cores and vacuumed material were significant for 19 of 46 species whose density was > 1/m2 in cores. Seeds of 10 species in vacuumed material were common as plants in standing vegetation, but seeds of 13 species (mostly shrubs) growing on the site were not in cores or vacuumed material. Vacuuming the soil surface may be effective for obtaining a diverse supply of seeds for herbaceous plants common on flatwoods after fire. Some species in vacuumed material, however, may not be in proportion to seeds in soil and the vacuumed material will not include seeds of some shrubs that characterize Florida flatwoods communities.

The sonographic features of acute renal allograft rejection in humans and dogs are manifested by increase in renal cross-sectional area and reduction in renal cortical blood flow. These changes have not been investigated in cats. The objectives of this study were to evaluate sonographic and scintigraphic changes during acute renal allograft rejection in cats. Eight SPF, intact, adult, male cats received heterotopic renal allotransplantations. Immunosuppressive doses of cyclosporine and prednisolone were administered for 14 days and then discontinued to allow acute allograft rejection to occur. Serial measurements of renal cross-sectional area, resistive index (RI), echogenicity, and glomerular filtration rate (GFR) were performed to evaluate changes during acute rejection. Upon sonographic confirmation of absent diastolic blood flow or a 20% increase in cross-sectional area of the allograft, a nephrectomy and histopathologic evaluation were performed. Acute allograft rejection was confirmed histologically in all cats. Significant increases in renal cross-sectional area (P < 0.001) occurred postoperatively and during rejection. There were no significant changes in RI (P= 0.43) at any time. A subjective increase in medullary echogenicity and a decrease in corticomedullary demarcation were observed in the rejection period. While GFR decreased significantly in the immediate postoperative period (P < 0.001), no further change occurred during rejection (P= 0.42). Changes in RI and GFR do not appear to be sensitive indicators of acute renal allograft rejection in cats. Serial measurements of renal cross-sectional area appear to be a sensitive method for the early diagnosis of allograft rejection in feline renal transplant recipients.

One method of obtaining seeds of native plants may be to let seeds fall to the soil surface and collect them by vacuuming. We evaluated this method by comparing plants that germinated from material vacuumed after fire with plants that germinated from seeds found in cores taken from the top 25 mm (1 in) of soil in a Florida flatwoods plant community before and after fire. A total of 76 species were identified in cores, of which 66 species were found before, and 60 species after, fire. No differences attributable to fire were found for seed density (3261 seeds/m2 [2740/yd2]) or concentration in cores (282 seeds/kg [128/lb]). Vacuumed material contained seeds of 58 species (54 in common with cores) with a density of 170 seeds/m2 [142/yd2] and a concentration of 451 seeds/kg (204/lb). Species correlations between cores and vacuumed material were significant for 19 of 46 species whose density was > 1/m2 in cores. Seeds of 10 species in vacuumed material were common as plants in standing vegetation, but seeds of 13 species (mostly shrubs) growing on the site were not in cores or vacuumed material. Vacuuming the soil surface may be effective for obtaining a diverse supply of seeds for herbaceous plants common on flatwoods after fire. Some species in vacuumed material, however, may not be in proportion to seeds in soil and the vacuumed material will not include seeds of some shrubs that characterize Florida flatwoods communities. Abstract

In the southeastern U.S., few warm-season legumes grow rapidly, have high nutritional value, and tolerate high rainfall and temporary waterlogging. Soybean [Glycine max(L.) Merr.] and cowpea [Vigna unguiculata(L.) Walp.] are two warm-season legumes that are fairly well adapted to growing conditions in the southeastern U.S., however little is known about their production under high moisture and high temperature conditions. This study examined the feasibility of growing soybean and cowpea and their nutritional value under specific stress conditions common in subtropical environments. Significant (P< 0.05) dry biomass (DB) differences were found among soybean averaging 2.8 ton/acre (1999) to 3.0 ton/acre (2000) from a single harvest. Cowpea appeared to be more sensitive to saturated soil conditions; 'Florida Clay' cowpea yielded 0.4 ton/acre and 'Iron Clay' cowpea died from saturated soil. Mean differences in crude protein (CP) and in vitro organic matter digestion (IVOMD) among legumes were significant in 2000 (P< 0.012) and 2001 (P< 0.019), but not in 1999. Highest IVOMD yields were noted for 'F94-2290' Long Juvenile (LJ) (3554 lb/acre in 1999) and 'Biloxi' (3925 lb/acre in 2000; 3074 lb/acre in 2001). These data indicate that soybean with high DB yields are best suited for forage production under subtropical environmental conditions. Long Juvenile soybean and Biloxi performed best overall, while cowpea tended to be more sensitive to excessive moisture and wet soil conditions. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © 2005. . © 2005 Plant Management Network.

Seasonal and fertilization effects on seed production were investigated for a north Florida ecotype of lanceleaf coreopsis (Coreopsis lanceolata L.) grown in containers. Since containerized ecotypes of native, herbaceous species are frequently grown using nutrient regimes lower than those for production of typical garden plants, Osmocote 18N–2.6P–10K (18–6–12; 8–9 month formulation) was incorporated into the soilless substrate at one-half the low, low and medium label rates for container-grown plants [1.8, 3.6, and 5.4 kg/m3 (3.0, 6.0, and 9.0 lb/yd3], respectively. Seed were harvested in June, and then again from July–October after plants had been cut back and reflowered. Seed production was greatest for the June harvest based on the number and mass of filled seed per seed head as well as the number of mature seed heads per plant. Number of mature seed heads was directly related to fertilizer rate but this effect varied by harvest season. Seed head production was substantially more responsive to increasing fertilizer rate for the June harvest than for the July–October harvest, which was one of the primary reasons for greater seed production in June. There were also 37% more filled seed per seed head for the June harvest than for the July–October harvest. Seed in June were 67% viable but only 21% of the viable seed germinated. The July–October seed were only 24.7% viable but half of them germinated. Seed harvested during July–October germinated faster than seed harvested in June.

The purpose of this study was to identify oxidative damage to renal allografts during graft rejection by evaluating changes in oxidative markers and plasma lactate levels in feline renal allotransplant recipients. Heterotopic renal allotransplantations were performed between 8 adult feline cross-matched donors. Following 14 d of immunosuppression, the drugs were discontinued to allow allograft rejection. Baseline and serial postoperative evaluations of serum creatinine, plasma lactate, plasma thiobarbituate reactive substances (TBARS), plasma creatol, urine creatol, and renal sonographic cross-sectional area were performed. When sonographic evaluation revealed the absence of blood flow to the allograft, the rejected kidney was nephrectomized and evaluated histopathologically. Allograft rejection occurred in all cats by day 26. A significant elevation in body temperature occurred during the rejection period. No significant change was observed between any of the time periods for plasma TBARS, creatol, or urine creatol. There was a significant decrease in plasma lactate levels throughout the study. Markers of oxidative stress from venous blood did not reflect renal allograft rejection in cats with a normally functioning native kidney. Renal allograft rejection may be associated with significant increases in body temperature and warrants further investigation.

The results of our 2 long-term studies indicate that while it may be best to restore a site with wiregrass (Aristida beyrichinia Trin. & Rupr. [Poaceae]) obtained from a similar site, it does not seem to be essential. In the first study, after 12 y, plants grown on a flatwood site in south-central Florida from seeds collected at a sandhill site (2 locations) in north-central Florida had 83% survival and average aboveground dry mass was 39 g/plant (1.4 oz) with basal diameter of 11.6 cm (4.6 in). In a second study, wiregrass plants from seeds collected at 8 locations (8 entries) across Florida were grown on a flatwood site in central Florida. Four of these entries were also grown on a sandhill site in north Florida. After 4 y on the flatwood site, one entry originating from a nearby flatwood survived better (88%) than the 7 other entries. One entry from a sandhill was notably inferior in survival (3%), but for the remaining 6 entries survival was similar (average 32%). On the sandhill site, the same entry of flatwood origin that had 88% survival on a flatwood had 92% survival, while the other 3 entries averaged 7% survival. Plant dry mass and diameter were not strongly associated with plant origin. Mass averaged 14.8 and 3.1 g/plant (0.52 and 0.11 oz) and diameter averaged 63 and 30 mm/plant (2.5 and 1.8 in) on the flatwood and sandhill sites, respectively.

Tissue-cultured creeping bluestem (Schizachyrium scoparium var. stoloniferum (Nash) J. Wipff [Poaceae]), grown in pots containing sand tailings or overburden from a Florida phosphate mine, had shoot (4.6 g/plant [0.16 oz]), root and rhizome mass (5.2 g/plant [0.18 oz]), and vegetative tiller density (4.2 g /plant [0.15 oz]) similar to that obtained from plants started from rhizomes. Seeds of creeping bluestem germinated on mine soil but failed to grow. In the field, tissue-cultured bluestem survival averaged 88% over January, July, and October planting dates on sand tailings compared with 67% on overburden. One year after October planting, total tiller density and aboveground plant dry mass was 63.5 and 117 g/plant (2.24 and 4.13 oz), respectively, on sand tailings compared with 50 and 107 g/plant (1.76 and 3.77 oz), respectively, on overburden. Except in the October planting, soil did not affect bluestem plant diameter (mean 24.2 cm [9.5 in]). Because creeping bluestem produces few seeds, tissue culture can provide plants that establish and grow well on land after phosphate mining. Weed control will be essential to success.