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Abstract
Moisture content and levels of pectin pectylhydrolase (PE) and poly (1,4-α-D-galacturonide) glycanohydrolase (PG) were evaluated for eight commercial cultivars of snap bean (Phaseolus vulgaris L.) over four harvest periods. Moisture content varied from 80.8% to 91.7%. Cultivar and harvest period moisture contents differed significantly. PE activity ranged from 208 to 896 units/g dry pod tissue, and PG ranged from 7.1 to 16.6 units/g dry pod tissue. Lines chosen to represent firm-podded, canned snap bean types exhibited higher enzyme activity levels than soft-podded types.
233 tomato accessions of the Central American tomato collection maintained at CATIE and 7 commercial cultivars were evaluated for resistance to 4 virulent strains of Pseudomonas solanacearum representing race 1 biovars 1 and 3. In general biovar 3 strains wilted seedlings faster than biovar 1 strains but by 20 days post inoculation no significant differences were noted in susceptible check ratings. Highly significant differences for disease index were noted but no line with complete resistance was found. Two CATIE accessions, 17334 and 17340, were found to be as resistant as Hawaii 7998 to all 4 strains. Accessions 17345 and MIP-CH1 were resistant to 3 strains.
Seven tomato lines and their 21 hybrid populations were evaluated for their ability to resist infection by 7 virulent strains of Pseudomonas solanacearum representing race 1 biovars 1 and 3. In all cases the Gardner and Eberhart model III analysis found GCA values to be significant. In 5 of 7 cases SCA was significant. In 4 cases the parent vs. cross contrast was significant. We conclude that resistance to Pseudomonas solanacearum is predominantly controlled by additive gene action and to a lesser degree by dominant gene effects. Hawaii 7998 was found to be resistant to all 7 strains, while Rotam 4 and Rodade were resistant to biovar 3 and one race of biovar 1 (UW 275). Venus and Saturn were resistant to 3 other biovar 1 strains. Hawaii 7998 transmitted disease resistance better than the other resistant parents but its small fruit size and indeterminate growth habit make it a poor choice for a hybrid parent.
Three tomato (Lycopersicon esculentum Mill.) cultivars were studied to determine the effect of nine dark-light regimes on anther callus initiation and growth. Prophase I (leptotene) stage anthers of `L-680A', `Licato', and `Ailsa Craig' were plated on Doy's basal medium 1 and provided with 2 to 10 weeks of dark treatment. After each dark period, each plate was transferred to a 16-hour photoperiod for the duration of the 10-week experiment. At this time, the number of anthers producing calli and the diameter of the calli produced were recorded. Callus number and diameter increased as the dark period duration increased. Callus diameter peaked at 8 weeks of dark treatment for `Ailsa Craig' and `Licato', whereas `L-680A' calli continued to grow over the entire 10-week dark treatment. Although the number and size of callus may continue to increase past 8 weeks of dark incubation, callus quality and appearance decreased noticeably during this period. For each additional week of dark period exposure, 7% more of the plated anthers produce callus, and callus diameter increases by 0.27 mm (12% of total growth). -
Anthers from. three tomato cultivars, `L-680A', `Ailsa Craig', and `Licato', were plated on DBM1 medium solidified with one of four solidifying agents, Bacto-agar, Gelrite, Noble agar, or Phytagar, to evaluate their ability to promote initiation and growth of tomato anther callus. The optimum concentration of each solidifying agent was compared with a liquid control. Optimum levels of the various solidifying agents were (in g·liter-1) Phytagar, 5; Gelrite, 3; Noble agar, 6 and Bacto-agar, 8. Both the number and diameter of calluses were affected by type of solidifying agent and anther genotype. Significant interactions were also found between tomato cultivars and solidifying agent. Noble agar produced good results with `L-680A' and `Ailsa Craig', but not with `Licato'. Bacto-agar reduced the number and size of callus by 38% when compared with the liquid treatment and by 42% when compared with the best agar treatment (Noble agar).
Seven tomato Lycopersicon esculentum lines, `Venus', `Saturn', `Rodade', `Rotam 4', `Hawaii 7998', `UC-82B', and `Stevens', and their 21 crosses were evaluated for their ability to resist infection by seven virulent strains of Pseudomonas solanacearum E.F. Sm. representing race 1 biovars 1 and 3. The Gardner and Eberhart model III analysis was used to evaluate the response of lines in crosses to P. solunaceurum infection. General combining ability mean squares were significant for all strains and in 5 of 7 instances specific combining ability mean squares were significant. In four instances the parent vs. cross contrast was significant. `Hawaii 7998' was resistant to all seven strains of P. solanacearum, whereas `Rotam 4' and `Rodade' were resistant to biovar 3 and two races of biovar 1. `Venus' and `Saturn' were resistant to two other biovar 1 strains. `Hawaii 7998' transmitted greater resistance than the other resistant parents, but its small fruit size and indeterminate growth habit make it a poor choice for a hybrid parent.
Abstract
A comparison of inheritance patterns and heritability estimates from a NCII crossing model which included green and red cabbage, Brassica oleracea L. Capitata group, indicated differences between green × green and red × green crosses. Green × green crosses exhibited dominance for few non-wrapper leaves, greater efficiency index, and smaller leaf size while red × green crosses showed the opposite dominance pattern.