A short-internode mutant of `Mainstream' muskmelon (Cucumis melo L.), designated Main Dwarf, was crossed with 13 normal and six short-internode cultivars or breeding lines. Regardless of whether Main Dwarf was crossed with a normal or short-internode line, the F1 family was normal for internode length. From crosses of Main Dwarf with normal lines, the F2 families segregated in a 3 normal: 1 short-internode ratio and the families from backcrosses to Main Dwarf segregated 1 normal: 1 short internode. Crosses of Main Dwarf with short-internode lines produced F2 families that segregated in a 9 normal: 7 short internode ratio and families from backcrosses to Main Dwarf that segregated 1 normal: 1 short internode. The segregation data from crosses of Main Dwarf with normal lines indicate that Main Dwarf has a recessive gene that conditions short internode. The segregation data from crosses of Main Dwarf with short-internode lines (five conditioned by si-1 and one conditioned by si-2) indicate that the recessive gene for short internode in Main Dwarf is not allelic to si-1 or si-2. The gene for short internodes in Main Dwarf is designated si-3.
Dean E. Knavel
Short-internode (SI) muskmelon (Cucumis melo L.) genotypes Ky-P7 (si-1 gene for SI) and Main Dwarf (si-3 gene for SI) were compared with the normal-internode (NI) cultivar Mainstream at various plant spacings or planting densities over 3 years. SI `Honey Bush' (si-1 gene for SI) and `Bush Star' (si-1 gene for SI) were included in 2 years. At double the population, SI plants (si gene type) produced ≈35% fewer fruit than `Mainstream' plants grown at one-half the population density. Spacing generally had no effect on average fruit weight, but increasing plant density of SI genotypes decreased the number of fruit per plant. Generally, doubling the density reduced leaf area and total plant dry weight, but had minimal effect on the amount of shaded leaf area. Ky-P7, `Honey Bush', and `Bush Star' plants had more leaf shading than `Mainstream' and Main Dwarf plants.
Dean E. Knavel
Plant spacing or population studies with normal internode-length `Calypso' and short-internode Ky Littleleaf (Ky-LL), both gynoecious-flowering, in 6-row beds for once-over harvest in 1987, 1988, and 1989 showed that increasing spacing increased leaf area per plant, but had no effect on leaf area, fruit number, and total fruit weight in Grades 1, 2, and 3 per growing area. `Calypso' plants had more leaf area than Ky-LL, but both had similar number and weight of fruit. The best spacing for `Calypso' and Ky-LL was 15 × 21.5 cm for an average of 28.5 plants/m2 (283,570/ha). Ark Littleleaf (ARK-LL), a monoecious-flowering normal-internode length genotype, had more leaves and greater leaf area than `Calypso' and KY-LL plants. Increasing bed spacing of Ark-LL plants from 30 × 30 to 30 × 45 cm increased leaf area, fruit number and fruit weight per plant, but not per growing area. For fruit number and weight in Grades 1, 2, and 3, the best row spacing of Ark-LL plants was a single row of 15 cm or a 30 × 30 cm double row with fruit weight of 25,500 and 27,000 kg/ha, respectively. Data for the three plant types in various row spacings to be conducted in 1990 will be presented.
Nanik Setyowati and Dean E. Knavel
Plant growth and yield of broccoli (`Green Comet'), and cauliflower (`Majestic', `Snow Crown') cultivars were evaluated by no-tillage (NT) and conventional tillage (CT) in the fall 1987 with NH4NO3 applied dry or through the trickle line. Total plant dry weight, plant stand, average head weight and number of heads harvested were not affected by tillage system. `Snow Crown' plants had less of the following leaf area, dry weight, plant stand, number of heads harvested, and total head weight, than `Majestic', especially in NT where NH4NO3 applied dry. In the greenhouse, cauliflower cultivars had similar leaf area, leaf dry weight, and mot dry weight at 30, 45, and 60 days after growing in sand culture while broccoli cultivars had similar leaf area, leaf dry weight, and mot dry weight after 35, 50, and 65 days. Generally, nutrient uptake was similar at each sampling date for cultivars within crops. Cultivars had similar leaf water and osmotic potentials when grown for 2 weeks in modified growth chambers at either 23.9 or 29.4 C day, and 18.3 C night. These plants were then root-pruned and grown in sand culture for 3 weeks. Leaf area, mot dry weight, and plant dry weight was greeter for `Majestic' than for `Snow Crown' and `Olympus'.
Deborah Johnson and Dean E. Knavel
Cracking and scarring of pepper (Capsicum annuum L.) fruit are under genetic control in families having the cultivar Serrano Chili as the P1 parent. Fruit of `Serrano Chili' exhibited slight cuticle cracking or scarring, with no wall cracking, for an average rating of 2.2. Fruit cracking ratings of the P2 parents (`Anaheim Chili', `Red Cherry Small', and `Keystone Resistant Giant') were 1.0, 1.0, and 1.8, respectively, whereas ratings for F, (`Serrano Chili' × `Anaheim Chili'), F1(`Serrano Chili' × `Red Cherry Small'), and F, (`Serrano Chili' × `Keystone Resistant Giant') were 3.5, 2.8, and 3.5, respectively—an indication of overdominance. Cracking ratings in F2 and BCP2 populations were very similar and shifted toward the mean of the P2 parent within each family, while ratings in the BCP1 populations were similar to the F1 mean. Estimates of gene effects for cracking were mostly dominant, with some additive effects in `Serrano Chili' × `Anaheim Chili' and `Serrano Chili' × `Keystone Resistant Giant' families, and additive × additive epistasis in `Serrano Chili' `Keystone Resistant Giant'. Plants selected from segregating generations for either high and low scarring or high and low cracking produced progeny the following year with lower ratings than their respective mother's rating the previous year. Since cracking and scarring were significantly correlated with length, diameter, and length: diameter ratio of fruit in only a few generations and in segregating progeny of selected plants, fruit shape has minimal relationship to cracking and scarring.
Dean E. Knavel and Robert L. Houtz
Plants of Main Dwarf, a short-internode mutant of the normal-internode `Mainstream' muskmelon (Cucumis melo L.), have shorter internodes, fewer nodes, less total vine length, less total dry weight, smaller leaves, increased chlorophyll concentrations, increased specific leaf dry weight, and increased ribulose-1, 5-bisphosphate carboxylase/oxygenase (EC 126.96.36.199, rubisco) activity per unit leaf area than `Mainstream' plants. Main Dwarf plants produce an equal number of fruit as `Mainstream' plants but are only half their size. Many of the plant and fruit characteristics for F1(Main Dwarf × `Mainstream') are similar to those of `Mainstream', except for greater leaf chlorophyll and rubisco activity per unit leaf area. The F1 (`Mainstream' × Main Dwarf) produced fewer and lower weight fruit than its reciprocal, F1 (Main Dwarf × `Mainstream').
C.R Roberts, Dean E. Knavel, John Snyder, Terry Jones, and Dave Spalding
Internal brown spot (IBS) was found consistently in the `Atlantic' cultivar at Lexington in 1967, 1968 and 1989, and at Owensboro and Quicksand, KY in 1987, Treatments of foliar and soil applied CaSO4 in 1987, soil-applied CaSO4 in 1988, and straw mulching in 1989 did not reduce IBS. Irrigation increased IBS because of larger tubers and increased Ca content of plants as compared with non-irrigated plants. Tubers showing IBS had higher Ca content in affected tissue than in non-affected tissue. Both IBS and Ca content of leaves increased as the plants aged.