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- Author or Editor: Warren R. Henderson x
C5 (sister line of ‘Sweet Princess’), ‘Sugar Baby’ and ‘Florida Giant’ cultivars of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai], and their hybrids were compared at the diploid (2x), triploid (3x) and tetraploid (4x) chromosome levels. Ovary, fruit and seed shape was significantly rounder in the polyploids than in the diploids. There was no change in fruit shape in the already round cultivar, ‘Sugar Baby’. Fruit weight and ploidy level were inversely related. Hollow heart was more severe in the polyploids. The polyploids had a significantly thicker rind, contained larger seed, and were more field resistant to anthracnose than were the diploids.
“Reciprocal” triploid hybrids [C5 (4x) x ‘Sugar Baby’ (2x) compared to ‘Sugar Baby’ (4x) x C5 (2x)] had significantly different means for ovary shape, fruit shape and anthracnose resistance. The “reciprocal” triploid hybrids differed significantly in 1 of 2 seasons for the traits fruit weight, hollow heart incidence, rind thickness, and seed shape. In breeding seedless watermelon hybrids it is important to consider the parent cultivar used as the seed (tetraploid) parent.
Crosses were made between diploids and tetraploids of C5, a sister line of ‘Sweet Princess’ watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] which was resistant to anthracnose (Glomerella cingulata var. orbiculare, S. F. Jenkins & Winstead races 1 and 3) and ‘Sugar Baby’ (SB) susceptible to anthracnose. There was no significant difference in anthracnose resistance among C5 (2x, 3x, 4x,), nor among SB (2x, 3x, 4x). The diploid hybrid SB(2x) × C5(2x) was similar in resistance to its tetraploid hybrid, SB(4x) × C5(4x). C5(2x) × SB(2x) was slightly less resistant than its reciprocal hybrid SB(2x) x C5(2x). The triploid seedless hybrid, C5(4x) × SB(2x) (ArArar), was significantly more resistant than its “reciprocal” hybrid, SB(4x) × C5(2x), (Ararar).
Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] flesh color is controlled by several genes to produce red, canary yellow, salmon yellow, and orange. Our objective was to study the interaction of three gene loci with two or three alleles at each C (canary yellow vs. red), y (salmon yellow vs. red), yo (orange), and i (inhibitory to C permitting Y to produce red flesh color). Five crosses were used to study gene action: `Yellow Baby' × `Sweet Princess', `Yellow Baby' × `Tendersweet Orange Flesh', `Yellow Baby' × `Golden Honey', `Yellow Doll' × `Tendersweet Orange Flesh', and `Yellow Doll' × `Golden Honey'. Based on the performance of six generations (PA, PB, F1, F2, BC1A, and BC1B), the parents had the following genotypes: `Yellow Baby' = CCYYII, `Yellow Doll' = CCYYII, `Sweet Princess' = ccYY ii, `Tendersweet Orange Flesh' = ccyoyoII, and `Golden Honey' = ccyyII. Segregation of flesh colors in the progeny of the five families demonstrated that there was a multiple allelic series at the y locus, where YY (red) was dominant to yo yo (orange) and yy (yellow). Also, yoyo was dominant to yy. In conclusion, epistasis is involved in genes for the major flesh colors in watermelon, with ii inhibitory to CC (Canary), resulting in red flesh, and CC in the absence of ii epistatic to YY, producing canary flesh.
Eight stamenless tomato mutants (Lycopersicon esculentum Mill.) were intercrossed in a half-diallel design to determine allelic relationships. Two allelic series were represented among the mutants. One series included sl, sl 2 , sl 5, cs, and fl. The 2nd series included bn, sl?, and pms. No allelic interactions occurred between members of the 2 series. Fruit and seed set resulting from cross-pollinations varied greatly among the mutants. The stamenless types, with the exception of sl 2, do not appear to be promising for use in producing hybrid tomato seed because of poor fruit and seed set.
Preharvest foliar applications of ethylene biosynthesis inhibitors (aminooxyacetic acid and alpha-aminoisobutyric acid) to ‘Dorchester’ and ‘Campbell 37’ processing tomatoes (Lycopersicon esculentum Mill.) did not adversely affect fresh fruit quality (i.e.)pH, soluble solids, color, core length, core diameter, and pigmentation) or canned quality (i.e.; color, wholeness, vascularization, and acceptability). Neither total marketable yields, nor the percentage of mature green fruit were increased over untreated controls by any of the inhibitors.
Inhibitors of ethylene biosynthesis—aminoethoxyvinylglycine, aminooxyacetic acid, and α-aminoisobutyric acid—inhibited ethylene and lycopene biosynthesis in 1.5-cm disks of excised pericarp tissue of tomato (Lycopersicon esculentum Mill. cv. Michigan-Ohio Hybrid). Application of 10 μl/liter ethylene promoted normal lycopene synthesis, but did not stimulate ethylene synthesis.
Two inbred lines of fresh-market tomato (Lycopersicon esculentum Mill.), NC 20G-1 and NC 53G-1, both exhibiting prostrate growth habit (PGH), were crossed with the upright growth habit cultivar Piedmont and advanced to the F2 generation. Plants of each F2 population were grown without plant support on black plastic and subjectively rated in field plots for PGH. Extreme upright and prostrate plants were chosen from each F2 population for harvest. Mean comparisons between plants of extreme upright and prostrate habit showed increased total and marketable yields from plants with a prostrate habit. Decay and groundscarring of fruit were less in prostrate than in normally upright plants; the percentage of misshapen fruit was similar in both. The PGH character may be useful in increasing total and marketable yield of ground-culture tomatoes.
Prostrate growth habit (PGH) in tomato (Lycopersicon esculentum Mill.) lines derived from breeding material developed at the Agriculture Canada Research Station, Beaverlodge, Alberta, was the subject of a quantitative inheritance study. Plants with PGH have an increased lateral branch angle, relative to upright plants, and crown-set fruit supported above the soil surface making hand harvest easier. Genetic parameters were estimated in two families (20G and 53G), each containing PGH and upright-habit parental lines, F1, F2, and backcrosses to each parent. Field-grown plants were subjectively rated twice during the growing season. Broad-sense heritability of PGH in family 20G was estimated to be 0.65 and 0.71 for ratings of plant growth habit 6 and 9 weeks after transplanting, respectively, and 0.71 and 0.68 for those of family 53G. Narrow-sense heritability was estimated to be 0.83 and 1.05 for the two ratings in the 20G family and 0.77 and 0.78 in the 53G family. F1 and F2 means were not different from mid-parent values. The genetic variance was entirely additive and expression was influenced by the environment. The data did not support the hypothesis that PGH was controlled by a single gene.