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Vegetable Improvement Newsletter No. 14, February 1972
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Compiled by H.M. Munger, Cornell University, Ithaca, New York

1. Interlocular Cavitation in Snap Bean Pods

Paul E. Read, J.M. Lee, and David W. Davis

Department of Horticulture, University of Minnesota, St. Paul, Minnesota 55101

Studies of interlocular cavitation (IC) in snap bean pods have been carried out in this department for 3 years. The incidence of IC has been known to decrease product quality by; (1) causing more sloughing of pods during cooking, (2) causing more tissue separation after canning and freezing, (3) producing more malformed pods.

Continuous high soil moisture and low temperature during the early stages of pod development and some other environmental factors favored the incidence of IC. The incidence of IC can be successfully minimized by cultural practices such as proper irrigation schedule, proper planting times, and by some growth regulators. It is interesting to note that not only different varieties but also different lines developed in the same variety show significant differences in the incidence of IC, indicating future needs of proper breeding efforts. Genetic and selection studies are underway in this department.

It is recommended that the evaluation of pod quality, both in fresh and processed products, should consider IC as an important quality factor.

2. An Orange Cauliflower

C.C. Filman

Muck Research Station, R.R. 4, Bradford, Ontario

A cauliflower with an orange curd appeared in a grower's field of Stokes Extra Early Snowball near Bradford, Ontario in 1971.

At "tying up" time the smaller curd was an attractive, glossy, medium orange color. At harvest time, approximately August 26, the curd was still the same attractive orange color. The size, shape, and compactness of the curd was the same as for Extra Early Snowball.

The epidermis of the leaf, leaf petiole, and main stem were normal green in color. The internal color of the leaf petiole and main stem was medium to light orange.

The habit of growth and plant size appeared to be identical to that of Extra Early Snowball.

Dr. D.G. Walkey, Canada Dept. of Agriculture, 6660 N.W. Marine Drive, Vancouver 8 B.C., propagated it vegetatively. Seed has not yet been produced and consequently nothing is know about the inheritance of this characteristic.

The orange cauliflower is attractive and distinctive. It may have use in commercial breeding or in genetic studies.

3. A New Type of Clip for Cucumber Pollination

John L. Bowers

Department of Horticulture and Forestry, University of Arkansas, Fayetteville, Arkansas, 72701

We have found that the ladies single hair clip (item #449 Luna Clips), obtained from our local wholesale Beauty Supply Store, has been the most effective piece of equipment for bagging cucumber and cantaloupe flowers. The spring tension of this particular clip is just with respect to keeping the flower closed without injuring the corolla. Supplier or handler of this product made in Japan is Continental Hair Products, Inc., Brooklyn, New York, 11223.

The ease of bagging flowers with this clip thus saving time in the pollination operation has been responsible for us adapting this procedure and dropping the cellophane tape method. It is slightly more expensive but saves considerable time.

4. Pepper Virus Tolerance

T.A. Zitter and H.Y. Ozaki

University of Florida, Agricultural Research and Education Center, Belle Glade, Florida, 33430 and Agricultural Research Center, Morikami, Delray Beach, Florida, 33444, respectively

In tests conducted in the field and greenhouse during the past 2 years, two Brazilian pepper cultivars have shown tolerance to naturally occurring severe strains of both tobacco etch virus (TEV) and potato virus Y (PVY). Both Avelar and Agronomico 8 at the same time are immune to two additional common strains of TEV and an additional common strain of PVY. Virus tolerance is best exhibited in Avelar, with symptom expression delayed for up to 3 weeks following mechanical inoculation. A similar finding was observed in the field following natural (aphid) inoculation. Symptoms appeared soon in Agronomico 8 and tended to be more easily observed.

5. Mosaic Infection of TMV Resistant Tomatoes

Marco A. Soto and H.M. Munger

Department of Plant Breeding, Cornell University, Ithaca, New York, 14850

In a field planting in the summer of 1971, a high incidence of mosaic was observed in tomatoes that were expected to be resistant to tobacco mosaic virus (TMV). This was late (June 14) planting of symptomless plants selected from progenies inoculated in the greenhouse with TMV. The major part of planting consisted of 8th and 6th backcrosses to Manapal and Floralou respectively, carrying the TM-2a gene originally obtained from Alexander in Ohio. In July these plants developed severe leaf mottling and stunting, and they produced only a few small distorted fruits, mostly without viable seed.

At first it was assumed that a virus, probably cucumber mosaic, had moved in from an adjacent older planting of tomatoes. This seemed unlikely when it was observed that the few progenies in the late planting carrying the Tm-2 gene (obtained from Pecaut in France) and TM-2nv (originally from Soost) were growing normally. Likewise, uninoculated plants of Manapal, Floralou, Floradel, and Vendor showed only slight or no leaf symptoms and produced fruit normally. This led to the assumption that high summer temperatures had broken down resistance as previously reported for plants heterozygous for TM-2a. However, this was not supported by the behavior of plants presumably homozygous for TM-2a. Eight plants of Ohio MR9, MR12, and 2401 had been inoculated in the greenhouse and none showed symptoms at field setting. Four of each were set in the field and 7 of the 12 plants developed more severe symptoms than the heterozygous plants in that they produced even less fruit, essentially none at all. On the other hand several progenies that were apparently homozygous for TM-2a following 4 backcrosses to Floralou generally produced many times as much fruit as the heterozygous plants with Floralou or Manapal background or homozygous plants of the Ohio varieties, suggesting that both background genotypes and heterozygosity of the TM-2a gene may be influencing the reaction.

Many of the plants showing mosaic symptoms were assayed for virus in Samsum NN tobacco. The appearance of local lesions and in some cases systemic infection indicated that TMV and some other virus were present. Other indicator plants confirmed the presence of TMV and suggested that the other virus was CMV. Seedlings of Ohio MR12 have not become infected when inoculated with the TMV isolated from the field. This raises the question as to whether the presence of another virus such as CMV may render the homozygous TM-2a plants susceptible to TMV.

While the explanation is not clear at this point, the extreme reaction of certain genotypes homozygous for TM-2a when TM-2 and TM-2+ were affected much less or not at all suggests some caution in the utilization of the gene.

6. TMV Resistance and Fertility

J. Farkas and Gy. Meszoly

Vegetable Crops Research Institute, Kecskemet, Hungary

Tm and Tm-2a genes in homozygote condition have no essential effect on the quality of the pollen/ stainable pollen with carmine-acetic acid 93-98%/ in our determinate or indeterminate strains. The pollen quality depends more on the change of external factors/ temperature, humidity/ in resistant lines than in the sensitive ones. Seed-setting is normal in sensitive plants with resistant pollen and inversely.

The reason of the poorer fertility can be sought for in the structure of the flower. The fruits of some strains have many locules: the stigma is large and it closes the sterile tip of the anther, inhibiting normal pollination partly or entirely/ the setting is 30-50% in the fall glasshouse crop- based on 2 trusses, cut above 2 trusses, with vibration. The smallest stigma is found in 01/oval/homozygote strains with 2 locules: the fertility of the resistant lines is similar to that of the sensitive ones/ oval strains: 70-85%, Moneymaker: 75-80%. The advantage of 01 in fertility appears also in TMV-resistant F1 hybrids.

7. Uncatalogued Vegetable Varieties Available for Trial in 1972

This list is aimed at facilitating the exchange of information about potential new varieties, or new varieties which have not yet appeared in catalogues. Persons conducting vegetable variety trials who wish seed of items on this list should request samples from the sources indicated.

It is the responsibility of the person sending out seed to specify that it is for trial only, or any other restriction he may want to place on its use.

Crops are listed alphabetically. For each entry the following information is given: Designation, source of trial samples, outstanding characteristics, variety suggested for comparison (not given separately if mentioned in description), status of variety (preliminary trial, advanced trial, to be released, or released) and contributor of information if different from source of trial samples. Where several samples are listed consecutively from one source, the address is given only for the first.

8. Stocks Desired