A tomato (Lycopersicon esculentum Mill.) breeding line (81B416) with' resistance to anthracnose caused by Colletotrichum dematium was crossed to three susceptible genotypes. Parental, F1, F2, and backcross populations were analyzed in the cross with `US28', while parental, F1, and F2 populations were tested in crosses of 81B416 with `US141' and 81B9. Inheritance of resistance was primarily additive, but 3- and 6-factor scaling tests indicated the presence of dominance and epistatic effects. The average broad-sense heritability estimate was 0.57; narrow-sense heritability was estimated at 0.42.
Timothy J Ng, Anita N. Miller and T.H. Barksdale
Ursula K. Schuch, Anita N. Miller and Leslie H. Fuchigami
Dormant coffee (Coffea arabica L.) flower buds require water stress to stimulate regrowth. A xylem specific watersoluble dye, azosulfamide, was used to quantify the uptake of water by buds after their release from dormancy by withholding water. In non-stressed flower buds, the rate of water uptake was generally slower and variable. In stressed flower buds, the rate of uptake tripled from one day to 3 days after rewatering and preceded the doubling of fresh and dry weight of buds. Free, ester, and amide IAA levels of developing flower buds were measured by GCMS-SIM using an isotope dilution technique with [13C6] IAA as an internal standard. Throughout development, the majority of IAA was present in a conjugated form and the dominant form was amide IAA. The proportions of amide and free IAA changed rapidly after plants were water stressed until day 3, and preceded the doubling of fresh and dry weight. Correlation coefficients of 0.9, 0.7, and 0.7 (p<0.l) were found between auxin content and fresh weight, dry weight, and rate of water uptake, respectively.
Anita N. Miller, Porter B. Lombard, Melvin N. Westwood and Robert L. Stebbins
`Napoleon' grafted onto Colt, F/12-1, and MxM60 rootstock were planted into three types of tree holes: augered; backhoed, and backhoed plus fumigation. The auger treatment resulted in lower yields, smaller trunk cross-sectional area (TSCA), and smaller canopy volume when compared to backhoed holes. Fumigation had no significant effect. Trees on Colt rootstock were more precocious, had a smaller TCSA and canopy volume, greater cumulative yield efficiency, and, in 1987, the smallest fruit weight. The yield efficiency of Colt was the highest until 1988, when it was surpassed by MxM60, but was still similar to F/12-l. Yields were highest on trees of MxM60 in 1987 and 1988.