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The environment substantially affects the performance of tomato (Lycopersicon esculentum Mill.) genotypes in Latin America and the Caribbean (LAC). Therefore, stability analysis can be used to select stable, high-yielding genotypes. Nine openpollinated and six hybrid tomato genotypes and the most representative local tomato cultivar were evaluated at 20 LAC locations. Each cultivar's yield stability was quantified using the regression of individual genotype's yield on the environmental index, which was measured by the mean of all the genotypes grown in an environment. A high-yielding and stable tomato cultivar had a mean yield higher than the general mean, b1 (coefficient of regression) = 1, s2 d (deviation from linearity) = 0, and r 2 (coefficient of determination) >0.50. `Narita' (hybrid) and `Dina RPs' (open-pollinated) were the most stable genotypes for marketable-fruit yield in LAC. `Flora Dade', an open-pollinated genotype that is grown widely in LAC had unstable marketable-fruit yield. Neither heterogenous composition of an open-pollinated genotype nor heterozygosity per se of the hybrids could explain the yield stability achievement across environments. Therefore, alleles that confer broader adaptation might be required to achieve tomato yield stability across environments. Hence, it is possible to select for yield stability in tomato.
Abstract
Fall and late-winter treatments of (2-chloroethyl)phosphonic acid (ethephon) at 2500 or 5000 ppm reduced bolting of fall-planted, short-day cultivars of onion (Allium cepa L.). Ethephon inhibited plant growth and reduced bulb size. Ethephon reduced yields when bolting in control plots was low or when cool spring weather restricted growth. With warm spring weather and 18% bolting in control plots, ethephon reduced bolting to 3% with no effect on yield. Ethephon caused some winter plant loss in 1 of the 3 years. Loss was greatest when higher rates of ethephon were applied in the fall to very young plants.
Abstract
Late-winter application of 5000 ppm (2-chloroethyl)phosphonic acid (ethephon) to fall-seeded short- day onions (Allium cepa L.) retarded leaf growth and inhibited bolting. Bolting inhibition was significantly correlated with bulb diameter at time of treatment. Bolting inhibition was greatest when bulb diameter was 0.9 to 1.6 cm at time of treatment. Bulb diameter in late February or early March was an effective criterion for the effectiveness of ethephon treatment to reduce bolting. When ethephon treatments greatly reduced bolting, the number of harvestable bulbs and yields were increased, but when bolting percentage in control plots was low, ethephon reduced yield by decreasing average bulb weight at harvest.
Abstract
Seedlings of bean, (Phaseolus vulgaris L.), were separated into scions and rootstocks using a V-shaped razor blade secured in a cutting block and mounted on a pair of electrician's pliers. Precise cuts could be made rapidly and easily, and the use of a hair clip eliminated the need for wrapping and unwrapping the graft. Grafted plants were transplanted in the greenhouse and to the field with a high degree of success. Components of seed yield, plant weight, and harvest index (ratio of seed weight to dry weight of aerial portion of plant) were affected by grafting on either the same strain or other strains used as rootstocks.
Abstract
I wish to point out a discrepancy in the conclusion on the value of the J-14 hydraulic press by A.H. Markhart, III, and B. Smit-Spinks [HortScience 19(l):52–54, Feb. 1984] that the J-14 readings prevent reliable predictions of the Scholander pressure bomb for leaf water potential measurements.
Abstract
We compared 9 dry bean (Phaseolus vulgaris L.) strains characterized by the following architectures for seed filling, yield, and components of yield: small bush, tall erect bush, classic II, and architype. Small and tall erect bush are determinate in growth habit; classic II is indeterminate and produces a short vine. Architype is erect, contains 2–4 branches angled acutely upward, grows to about 75 cm, terminates in a short vine, and does not lodge at maturity. Seed dry weight vs. days after 50% flowering data were fit to a cubic polynomial to calculate the rate and duration of seed filling. Small bush produced the greatest pods/m2 of the groups, but pod set was offset by a high percentage of shriveling and seed abortion. The architype outyielded the tall erect and small bush groups by 34 and 45 %, respectively, which was due to a greater number of seeds/pod, seeds/m2, and heavier seeds. The heavy seeds of the architype compared to the bush appeared to be due to a longer filling duration, because linear seed filling rates were similar. The architype filling duration was 11.3 days compared to 5.7 and 7.0 days for small and tall erect bush, respectively. The longer architype filling duration may be associated with its ability to prolong the duration of photosynthesis. The 17% yield increase of the architype over classic II was due to improved lodging resistance through a modification of the morphology by reducing branches and narrowing the plant canopy.