Good Fruit Set Research Articles

Evaluation of Daminozide on ‘Concord’ Grapevines of Different Fruit Set Potential1

Abstract Succinic acid-2, 2-dimethylhydrazide (daminozide), at rates of 0, 1000, and 2000 ppm, was applied between first and peak bloom to 2 adjacent ‘Concord’ (Vitus labrusca L.) vineyards: a 9-year-old vineyard with a histoty of good fruit set and a 19-year-old vineyard with a history of poor fruit set. No significant yield increase was obtained in the young vineyard, but there was a tendency for lower soluble solids and poorer juice color due to daminozide. Yields were increased by 2.4 and 3.3 MT/ha by 1000 and 2000 ppm daminozide, respectively, in the older vineyard with no significant effect on juice quality. The one-year increase in yield of grapes in the older vineyard was accompanied by a reduction in vine size.

Floral Development and Compatibility Studies of Carica Species1

Abstract The period between flower bud emergence and anthesis for Carica goudotiana (Tr. & Pl.) Solms, C. cauliflora Jacq., C. parviflora (A. DC.) Colms., C. monoica Desf. and C. papaya L. ranged from 27-47 days. Flowers of C. parviflora showed peak anthesis between 8 and 10 AM, while in the other 4 species, peak anthesis occurred between 4 and 8 PM. Pollen of the 5 species and C. pennata Heilborn, Svensk showed satisfactory viability in vitro. Pollen germination was best in media at pH 5.5-7.5. Sibmating C. cauliflora, C. pennata, and C. parviflora produced fruit sets above 80%, although seed viability of the latter 2 species was low. Under the conditions of this study, relatively strong intraspecific incompatibility was shown between green and red segregants of C. goudotiana and between El Salvador and Venezuela collections of C. cauliflora as indicated by low fruit set percentages. Only C. cauliflora from El Salvador produced good fruit set and high seed viability from sib-pollinations.

Fruit Set of Sweet Pepper (Capsicum annuum L.) Under Plastic Covers1

Abstract The effects of polyethylene (PE) and polyvinyl chloride (PVC) plastic film tunnels (perforated, whole and double layer) on fruit set and yield of winter peppers were tested alone and in combination with soil mulches of black bitumen and black PE film. Whereas double4ayer cover induced more vigorous plant development, good fruit set on lower nodes, resulting in higher early yields of large fruit, was obtained only from plants covered throughout flowering by perforated plastic film. The addition of bitumen mulch resulted in higher total and early yield, while black PE mulch reduced the early yield, Factors inducing flower abscission when double-layer plastic is in use during flowering, as well as the differences between black bitumen and black PE mulch, are discussed.

Studies on the Effect of Plant Growth Regulators on Certain Varieties of Grapes (Vitis vinifera L.)

Plant growth regulators are widely employed to secure good fruitset and development in many horticultural crops. They are now widely used in grape production for varied uses such as thinning of berries, improving the fruitset, hastening or delaying maturity of fruits (Weaver, 1956), increasing the size of berries (Weaver and Mc Cune, 1959 a), increasing the quality of berries (Weaver and Mc Cune 1959 a, b and c, Venkataratnam, 1964) and for inducing seedlessness in berries (Celestre, 1963, Blaha, 1963 and Coombe, 1965). The compounds of plant growth regulators like naphthalene com- pounds, phenoxy compounds and gibberellins are commercially used for such purposes. In India Krishnamurthi et al (1959) found the usefulness of gibberellic acid for improving the size and quality of Pusa Seedless variety of grape. In the light of the above findings, investigations were undertaken, to study the effect of plant growth regulators on some of the important varieties of grapes.

A male sterile pepper (C. annuum L.) mutant

1. After treatment of dry seeds of red pepperCapsicum annuum L. with X-rays a male-sterile mutant was discovered in the M2. 2. The male-sterile mutant segregates in a ratio of 3.28:1 (χ(2)=3.148, probability 0.07). 3. After an alternative cultivation of male-sterile plants and of a variety with good combining ability relatively good fruit-setting and seed production was obtained. 4. Grafting of male-sterile scions to normal stocks does not affect the male-sterile phenotype.

Application of certain hormones to prevent flower abscission in two potato (Solanum tuberosum) varieties

Investigations were undertaken to obtain flowers and fruit set in two potato varieties, namely, Canoga and Russet Burbank. Almost always in Russet Burbank, and quite often in Canoga, the flower buds drop. Seven hormones were used and a 25 p.p.m. aqueous solution of each was prepared. Potato plants were sprayed with hormones at different stages of plant development. These stages were; seed tuber stage, four-inch stage, fully grown plant stage, and flower bud stage. The results indicate that in the Canoga variety, flowers and fruit were obtained when the plants were sprayed with any of the above-mentioned hormones at any stage, but the fully-grown-plant stage proved to be better for hormone treatment since it affects flower development. At this stage the best flowering and fruit set were obtained by the application of 2,4-D followed by IBA, 2,4,5-TCPA, and 2,4,5-TCPP. In the case of Russet Burbank more selectivity as to stage of plant growth and type of hormone was required to obtain good flowering and fruit set. The four-inch stage proved to be better and at this stage the application of NAA and 2,4,5-TCPP gave the best results with IBA as third choice. These results were obtained from a single experiment. In order to make definite recommendations much more research will have to be conducted.