The active ingredient of a product known as “AmiSorb” is carpramid, a long-chained polyaspartate polymer. This product is currently being marketed as a soil or irrigation water applied nutrient absorption enhancer for vegetable crops. Our objective was to evaluate the growth, yield, and leaf photosynthetic responses of muskmelon (Cucumis melo L., `Caravelle') and bell pepper (Capsicum annuum L., `Enterprise') to a range of carpramid application rates under well irrigated and fertilized conditions. Carpramid solutions were applied at concentrations of 0, 200, 400, 600, and 800 mL·L-1 (0 to 0.18 mL per carpramid plant) in both greenhouse and field experiments. Biomass of individual plant parts and leaf area were measured at weekly intervals during the greenhouse experiment by destructive sampling. Light saturated leaf photosynthetic rates as a function of both carpramid treatment as well as leaf position on the vine were measured for muskmelon in the field experiment. Final yield was determined for both muskmelon and bell pepper in the field experiment. None of the plant response variables were significantly (P ≤ 0.05) affected by carpramid treatment in either the greenhouse or field experiments. Leaf photosynthetic rates increased from the youngest leaf on the vine to the sixth leaf, counting basipetally. We conclude that further research under nutrient deficient conditions may be warranted for this product.
We collected growth and yield data on eight cantaloupe cultivars and constructed a simple phenology model that uses local weather data to allow growers to quantify phenological growth and development to project harvest dates. Main vine plastochron interval (PI), time to harvest, and final yield were determined. PI was calculated for each cultivar × transplanting date combination as the reciprocal of the slope of main vine node number vs. growing degree days. Among the tested cultivars,`Ovation' and `Primo' produced significantly higher yields of marketable melons (51.3 Mg/ha, 49.5 Mg/ha, respectively), whereas `Santa Fe' produced the lowest (28.6 Mg/ha). The rest of the tested cultivars produced on average 34.4 Mg/ha. Fruit weight was significantly higher in `Morning Ice' (2.7 kg/fruit) and lowest in `Mission' (1.4 kg/fruit). There were also significant differences among cultivars in the number of marketable melons/ha, which ranged from 11500 melons/ha for `Morning Ice' to 32300 melons/ha for `Ovation'. Plant dry matter production was higher in `Ovation' and `Mission' than all the other cultivars. The relative days to maturity were significantly higher in `Morning Ice' and `Honey Brew' (115 days) and lower in `Gold Rush' (72 days). There were no differences found in days to maturity for `Mission', and `Ovation'(82 days). The average % of soluble solids content ranged from 9.5 for `Ovation' to 14.5 for `Mission' and `Honey Brew'. The variety cantaloupensis types are earlier in maturity than inodorus types. PI was significantly different for all cultivars. Main vine node number was a useful descriptor of vegetative development for cantaloupes. Procedures for calibrating and fitting the model for these cultivars will be discussed and outlined
Eight individual potatoes, exhibiting a wide range of quality characteristics, were cloned at the Texas A&M Vegetable Improvement Center, College Station, Tex., in order to produce a large number of slips for field trials. Leaf photosynthetic light response for six of these clonal selections was determined during a greenhouse experiment conducted at the Texas A&M Univ. Agricultural Research and Extension Center at Overton, Tex. Photosynthesis data were fit to a rectangular hyperbola in order to estimate light saturated leaf photosynthetic rate (Amax), quantum efficiency (QE), and dark respiration rate (Rd). Significant differences (P ≥ 0.05) were detected in all three of these parameter estimates among the six clonal selections. Parameter estimates ranged from 23.4 to 28.8 μmol (CO2) m-2·s-1, 0.056 to 0.071 mol (CO2)/mol (photons), and –0.9 to –2.0 μmol (CO2) m-2·s-1 for Amax, QE, and Rd, respectively. However, these differences were not clearly related to quality characteristics determined for these clones in field trials.