Arizona-Nevada Academy of Science

Effect of Hand Pollination with Nine Citrus Cultivars on Yields of Minneola TangeloAuthor(s): Joseph O. Moffett, D. Ross Rodney and Charles W. ShipmanSource: Journal of the Arizona-Nevada Academy of Science, Vol. 14, No. 2 (Jun., 1979), pp.47-49Published by: Arizona-Nevada Academy of ScienceStable URL: http://www.jstor.org/stable/40022200 .

Accessed: 14/06/2014 20:43

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

Arizona-Nevada Academy of Science is collaborating with JSTOR to digitize, preserve and extend access toJournal of the Arizona-Nevada Academy of Science.

http://www.jstor.org

This content downloaded from 185.44.78.156 on Sat, 14 Jun 2014 20:43:25 PMAll use subject to JSTOR Terms and Conditions

EFFECT OF HAND POLLINATION WITH NINE CITRUS CULTIVARS ON YIELDS OF MINNEOLA TANGELO.

JOSEPH O. MOFFETT, ! , 3 D. ROSS RODNEY, 2 and CHARLES W. SHIPMAN1 1 Carl Hayden Bee Research Center, AR, SEA, USDA,

2000 E. Allen Road, Tucson, Arizona 85719. 2

University of Arizona Experiment Station, Yuma 85364.

[238]

INTRODUCTION. - The Minneola tangelo (Citrus paradisi Macf. x C. reticulata Blanco) produces excellent fruit with good market acceptance, but yields in Arizona have been extremely variable. Some orchards have produced good crops in some years, while other orchards have consistantly produced so poorly or have produced so little fruit that the trees have been pulled.

In our studies in Arizona (unpublished data), the use of honey bees both with and without pollinator trees to increase yields on Minneola has given disappointing results. Poor yields in commercial Minneola

groves are also common in Florida (Krezdorn and Brown, 1975), India (Arora and Sharma, 1975), and South Africa (de Lange et al., 1973). Cross pollination by hand with pollen from other cultivars increased fruit set of Minneola flowers in Florida (Mustard et al., 1956), India (Arora and Sharma, 1975), and South Africa (de Lange et al., 1973). Therefore, we studied the effect of hand pollinating Minneola flowers with different citrus pollens on fruit set in Arizona.

METHODS AND MATERIALS. - The trees in the 1975 experiment were growing in nine commercial Minneola orchards and in the Yuma Valley and Yuma Mesa University of Arizona Experiment Station orchards. Four of the orchards (Baxter, McCain, Smith, and Valley) were in the Yuma Valley, six on the Yuma Mesa (Corliss, Heffner, Franks, Nutt, Van Horn, and Yuma Mesa), and one on the Wellton mesa. The orchards represented several different management methods and soils and were spread over a distance of more than 64 km. Two commercial orchards were used in the 1973 tests.

Each treatment was applied to five flowers per test tree except in the

Valley orchard. Ten trees were studied in each of nine commercial orchards. Only four trees were available for testing at the Yuma Mesa orchard. Because of a scarcity of flowers at the Yuma Valley orchard, 15 trees were used in this orchard to obtain the 50 flowers per treat- ment.

Test flowers were emasculated in the enlarged bud stage by removing petals and anthers with small scissors. The day after emasculation

stigmas of test flowers were rubbed with the anthers of the various cul- tivars.

Recently opened flowers were picked early in the morning of the

day they were used to supply anthers for pollinating. In 1973 flowers were hand pollinated in the McCain orchard on

April 10 and in the Frank orchard on April 1 1. In 1975, because of the variation between bloom among the different orchards, the earliest

flowering orchard (Yuma Mesa) was pollinated on March 25, while the last orchard to bloom (Franks) was not hand pollinated until April 18. Flowers in each orchard were emasculated when the orchard came into about 25% bloom and then hand pollinated the following day.

Each test flower was marked with a red tag. Treatments were identified by number and shape of punches in each tag, i.e., plain (open check), one heart (Lisbon lemon), two diamonds (Minneola), etc. Over 99% of the tags were recovered.

In 1976 the six treatments were: 1 . Open. These flowers were left alone to bloom naturally. 2. Emasculation only. 3. Emasculation plus Dancy tangerine (C. reticulata) pollen. 4. Emasculation plus Hamlin orange (C. sinensis (L.) Osbeck) pollen. 5. Emasculation plus Temple orange (C. temple Hort. ex Y. tan.)

pollen. 6. Emasculation plus Valencia orange (C. sinensis) pollen. In 1975 the ten treatments were: 1 . Open 2. Bagged (Blossom bagged in large bud stage to prevent insect

pollination. 3. Emasculation only (check). 4. Emasculation plus Fairchild tangerine (C. reticulata) pollen. 5. Emasculation plus Red Blush grapefruit (C. paradisi) pollen. 6. Emasculation plus Hamlin pollen. 7. Emasculation plus Kinnow mandarin (C. nobilis Lour, x

C. deliciosa (Ten.)) pollen. 8. Emasculation plus Lisbon (C. limon (L.) Burm. F) pollen. 9. Emasculation plus Minneola pollen.

1 0. Emasculation plus Valencia pollen. When the fruit matured, they were collected and counted. In 1975

the fruit was also weighed, and the seeds counted for each treatment. The seven cultivars were rated visually from one for most to seven

for least amount of pollen produced per flower on each of the 1 2 days between March 26 and April 18, 1975 when flowers were collected for hand pollination.

RESULTS AND DISCUSSION. - Hand-applied pollen from several citrus cultivars was effective in producing marketable fruit on Minneola. In 1973, the pollen from each of the four cultivars tested produced marketable fruit on more than 50% of the emasculated flowers that were hand pollinated (Table l).Only 2% of the emasculated (check) flowers that were not hand pollinated produced fruit.

In 1975, the pollen from five of the seven cultivars tested produced fruit on 20% or more of the emasculated flowers that were hand pollinated (Table 2). Less than 1 % of the emasculated (check) flowers receiving no hand pollination set fruit. Pollen from either Red Blush and other Minneola trees resulted in a 10% fruit set.

The best producing orchard produced 800% more fruit on the tagged flowers than the worst producing orchard.

Generally, the pollens producing the most fruit also produced fruit with more seeds (Table 3) and more size or weight. For example Minneola pollinated with Fairchild averaged 25 seeds per 10 fruit compared to less than 1 seed per 10 fruit produced on bagged or emasculated unpollinated (check) flowers. Also, fruit from flowers pollinated with Fairchild, which was the most effective pollen source, weighed 48% more per fruit than fruit from unpollinated emasculated (check) flowers.

In 1975 Hamlin produced the most pollen per flower followed by Red Blush, Valencia, Minneola, Fairchild, Lisbon, and Kinnow.

Apparently poor yields in some Minneola orchards in Arizona are caused by inadequate pollination. In some orchards most of the fruit

3 Present address: 501 Life Sciences West, Oklahoma State University, Stillwater, Oklahoma

74074.

47

This content downloaded from 185.44.78.156 on Sat, 14 Jun 2014 20:43:25 PMAll use subject to JSTOR Terms and Conditions

48 JOURNAL OF THE ARIZONA-NEVADA ACADEMY OF SCIENCE VOL. 14

Table 1 Fruit produced by Minneola blossoms that were hand pollinated with pollen from four citrus cultivars in two orchards near Yuma, Arizona in 1973.

Treatment Fruit Set At1 2

and Pollen Total Source Frank's McCain's (100 flowers)

1. Open (check) 6b 3b 9b Emasculated

2. None 2b 0b 2b 3. Dancy 30a 25a 55a 4. Hamlin 37a 31a 68a 5. Temple 34a 34a 68a 6. Valencia 29a 3()a 59a

1 50 blossoms (5 per tree) received each treatment in each orchard.

1 Means followed by the same letter differed significantly at the 1% level of probability by Duncan's multiple range test.

on the test trees was produced on the few flowers that had been hand pollinated. Even in orchards that had pollinator trees and some honey bee activity, the relatively large amounts of pollen applied by hand caused Minneola tangelo flowers to set much more fruit than open pollinated flowers.

Hamlin probably would be the best pollen source because it produces an abundance of pollen, blooms over a relatively long period, and

blooms at the same time as Minneola. Valencia would be the second choice. The two cultivars that produced the best results, Fairchild and Kinnow are not recommended as pollinators because both produce small quantities of pollen. Also Kinnow tends to bloom and bear alter- nate years, while Fairchild flowers for a shorter time than many other citrus cultivars. Although Dancy pollen set Minneola flowers adequately (Table 1), Dancy is not recommended in the Yuma area for two reasons. First, the fruit is unmarketable because a high percent of it

crystallizes. Secondly, some years Dancy trees produced few flowers.

Temple was not recommended both because of the difficulty of

selling these oranges and also because it often suffers frost damage in Yuma County.

Minneola flowers in this study apparently were neither highly self- fertile nor parthenocarpic, since both bagged flowers and emasculated flowers that were not hand pollinated produced very few fruit.

SUMMARY. - In 1973 in Yuma County, Arizona, 400 Minneola

tangelo flowers in two orchards were hand pollinated with pollen from four citrus cultivars, while in 1975, 3,640 flowers in 11 orchards were hand pollinated with pollen from seven cultivars. Depending on the pollen used, hand pollination increased the percent of flowers

producing fruit five to seven times in 1973 and two to six times in 1975 compared to flowers exposed to natural pollination.

In 1973 all four of the pollens studied (Dancy tangerine, Hamlin, Temple, and Valencia oranges) produced fruit on more than 50% of the flowers pollinated.

In 1975 set ranged from a low of 9.8% with Minneola pollen to a

high of 31.5% with Fairchild tangerine pollen. The set with other cultivars tested in 1975 ranked as follows: Kinnow mandarin (28.8%), Valencia orange (21.9%), Lisbon lemon (21.5%), Hamlin orange (20.6%), and Red Blush grapefruit (10.6%).

Table 2. Fruit produced in 1 1 orchards by Minneola flowers that were hand pollinated with pollen from seven citrus cultivars, Yuma County, Arizona, 1975.

Number of Fruit Produced by Number of Fruit Flowers Emasculated Before Bloom and then Produced by

Pollinated with Pollen from:1 Flowers

Open Bagged Total Fruit Orchard Nothing Polli- before All % Flowers Studied Fairchild Kinnow Valencia Lisbon Hamlin Red Blush Minneola (check) nated bloom Treatments Setting Fruit

Franks 28 28 34 16 22 17 12 0 8 0 165 33.0 Baxter 19 28 13 16 18 7 15 10 0 117 23.4 Wellton 26 21 19 11 15 9 2 0 0 0 103 20.6 Yuma Mesa 085 12 850000 38 19.0 Heffner 25 12 17 14 11 6 6 2 1 0 94 18.8 Corliss 24 15 6 9 9 4 7 0 3 1 78 15.6 Nutt 17 10 7 12 13 0 2 0 0 2 63 12.6 Van Horn 5 14 2 8 5 2 5 0 2 0 43 8.6 McCain 8 9 0 6 4 5 10 0 1 34 6.8 Smith 8 4 8 4 2 0 10 5 2 34 6.8 Valley 4 13 4 2 0 0 0 6 0 20 4.0

Total Fruit (520flowers) 164 150 114 112 109 55 51 3 25 6 789 15.2

% Flowers Set- ting Fruit2 31. 5a 28. 8a 21. 9b 21. 5b 21. 0b 10. 6C 9.8C 0.6e 4.8d 1.2e

1 50 flowers (5 per tree on 10 trees) were given each treatment in all orchards except at Yuma Mesa where only 4 trees were available (20 flowers/treatment) and Valley where 1 5 trees were needed to obtain 50 flowers/treatment.

2 Means not followed by the same letters differed significantly at the 5% level of probability by Duncan's multiple range test.

This content downloaded from 185.44.78.156 on Sat, 14 Jun 2014 20:43:25 PMAll use subject to JSTOR Terms and Conditions

JUNE 1 979 HAND POLLINATION WITH NINE CITRUS CULTIVARS ON YIELDS OF MINNEOLA TANGELO 49

Table 3. Effect of pollens from seven cultivars applied by hand to Minneola on fruit harvested, seed per fruit, and weight per fruit in 1 1 orchards in 1975. Yuma County, Arizona.

Average Pollen No. Fruit Harvested Average No. Seeds Weight (gm) Source from 520 Flowers per 10 fruit per fruit

Fairchild 164 24.9** 239** Kinnow 150 24.5 234 Valencia 114 21.2 241 Lisbon 112 16.5 216 Hamlin 109 19.5 231 Red Blush 55 16.0 222 Minneola 51 14.8 222 Open 25 3.3 209 Bagged 6 0.7 177 Emasculated 3 0.3 161

** There was a highly significant rank correlation between number of fruit harvested and both seeds and weight of individual fruit and also between seeds per fruit and weight per fruit.

In 1975 the fruit produced on the hand pollinated flowers varied from 4% to 45% among the 11 orchards. Less than 0.5% of the Minneola flowers left to develop naturally set fruit, and some orchards

produced almost no fruit. The pollens setting the most flowers also produced the largest and

seediest fruit. CONCLUSION. - Minneola flowers in this study were largely self-

sterile and nonparthenocarpic. Hand pollination of the stigma of Minneola flowers by pollen from any of seven other citrus cultivars increased the fruit set per 100 flowers several fold over either

unpollinated flowers or flowers exposed to natural pollination. When both fruit set and quantity of pollen produced are considered,

Hamlin was the best pollinator tree of the nine cultivars studied, and Valencia was second.

LITERATURE CITED

ARORA, J. S. and J. N. SHARMA. 1975. Studies on self incompatibility of Minneola and Orlando tangelo. Sci. Culture 4 1 :440.

DeLANGE, J. H., A. P. VINCENT and J. H. DeLEEUW. 1973. Pollination studies on Minneola tangelo. Agroplantae 5:49-54.

KREZDORN, A. H. and H. D. BROWN. 1970. Increasing yields of "Minneola", "Robinson" and "Osceola" varieties with gibberellic acid sprays and girdling. Proc. Fla. State Hort. Soc. 83:29-34.

MUSTARD, M. J., S. J. LYNCH and R. O. NELSON. 1956. Pollination and floral studies on the Minneola tangelo. Proc. Fla. State Hort. Soc. 69:277-281.

This content downloaded from 185.44.78.156 on Sat, 14 Jun 2014 20:43:25 PMAll use subject to JSTOR Terms and Conditions