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- Author or Editor: Bruno Quebedeaux x
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
Effects of water stress on superoxide dismutase (SOD) activities, changes in protein content, leaf water potential (Ψ l ) and growth were studied in drought-sensitive Kyokko (KK) and Ratan (RT), and drought-tolerant TM 0126 (TM) and VF-134-1-2 (VF) cultivars of tomato (Lycopersicon esculentum Mill.) in order to obtain fundamental information for breeding drought tolerant cultivars that may be adapted to water stress in many parts of the world. Growth of drought-tolerant TM and VF was greater than that of drought-sensitive KK and RT under water stress conditions. Leaf water potential (Ψ l ) decreased by water stress treatments in all the cultivars, but the reduction was much more rapid and pronounced in KK and RT than VF and TM. Ψ l of stressed cultivars decreased by 30% to 40% compared to the untreated control cultivars. The initial reduction in the range of 20% to 35% was more rapid in KK and RT than TM and VF. SOD activities were increased by water stress in all cultivars. Increase of SOD activities by water stress was much more rapid and pronounced in TM and VF than in KK and RT. Leaf protein concentration was decreased by the water stress treatments in all cultivars evaluated. In KK and RT, much more rapid reductions in protein concentration were observed than in TM and VF. The regression analysis of Ψ l and SOD suggest the possibility to using SOD activities as an additional screening criterion for tomato drought tolerance improvement.