David H. Byrne Department of Horticultural Sciences

 Temperature  Humidity

Department of Horticultural Sciences Texas A&M University Effect depends on the plant growth stage

 Dormancy  Flowering

 Fruit bud development  Fruit development

Department of Horticultural Sciences Texas A&M University High Chilling

Medium Chilling

Low Chilling

Department of Horticultural Sciences - Texas A&M University 1400 1200

1000 Average 850 800 600 550

400 200 0 1975 1978 1981 1984 1987 1990 1993 1996

Department of Horticultural Sciences - Texas A&M University 600

500

400

Average 300 250

200 150 100

0 1975 1978 1981 1984 1987 1990 1993 1996

Department of Horticultural Sciences - Texas A&M University

Department of Horticultural Sciences Texas A&M University Department of Horticultural Sciences Texas A&M University

Photo courtesy of Dr. George Ray McEachern

% of years

Chilling Zones

Department of Horticultural Sciences - Texas A&M University

Department of Horticultural Sciences Texas A&M University

Sensitive to high temperatures

Department of Horticultural Sciences Texas A&M University Kozai et al., 2004. J. Hort. Sci. Biotechnol. 79:533-537

Variety = “Hakuho”

40 Pollen germinates less 35 30 Pistal/ovule develop poorly 25 20 15 10

Percent fruit set fruit Percent 5 0 15 20 25 30 Temperature - C

Department of Horticultural Sciences Texas A&M University Warm Spring

Cool Spring

TXW1A40 TropicPrince

Texas A&M University, Fruit Breeding and Genetics Program 950 hours 650 hours 500 hours

Department of Horticultural Sciences Texas A&M University Round Fruit

Pointy Mean Temperature (°C) Fruit 0-50 days after bloom

Department of Horticultural Sciences Texas A&M University Susceptible Variety

950 hours 650 hours 500 hours

Resistant Variety

Department of Horticultural Sciences Texas A&M University During summer

Twins Blind nodes

Department of Horticultural Sciences Texas A&M University Department of Horticultural Sciences Texas A&M University Normal bud Bud of blind node

Pictures taken by Unaroj Boonprakob

Department of Horticultural Sciences Texas A&M University 120 100

80 60 40

% Blind Nodes % Blind 20 0 13 16 19 22 25 28 31 34 Maximum Temperature (C)

Research done by Dr. Unaroj Boonprakob

Department of Horticultural Sciences Texas A&M University

Department of Horticultural Sciences Texas A&M University  Tolerance to high temperatures  Mild (ie warm) winters (less chill requirement)  Bloom time  Fruit bud development  Fruit development

Department of Horticultural Sciences Texas A&M University Flordaking

Productive Early Large

Lack firmness Lack flavor Lack color Not round High Chill

Need longer season Medium Chill

Low Chill

Department of Horticultural Sciences - Texas A&M University  Adaptation: Mild Winter Conditions  Low and medium chill regions  Resistance to bacterial leaf spot

 Ripening series: early to mid season

 Varieties: Fresh Market  Peaches  Flesh color: yellow

Department of Horticultural Sciences - Texas A&M University

Especially for Tree Crops

Variety Chill Ripe

TropicPrince 150 Mid April

EarliGrande 250 Mid April

Thai Tiger 1193-1 150 Late April

TexFirst 200 Late April

Thai Tiger 1C4 150 Early May Tropic Beauty 150 Early May

Thai Tiger 1490-1 150 Early to mid May

Thai Tiger 1491-1 150 Mid to late May Variety Chill Ripe TexFirst 200 Late April Frost protection Flordaking 450 Early May Standard

TexKing 450 Mid May

Texstar 550 Late May

TexRoyal 550 Early to mid June TexPrince 500 Early to mid June  Expand products available  Yellow peaches  White peaches  Yellow nectarines  White nectarines  Donut peaches

 Adaptation: Mild Winter Conditions  Low and medium chill regions  Resistance to bacterial leaf spot  Ripening series: early to late season  Varieties: Fresh Market  Peaches, nectarines, flat peaches  Flesh color: yellow, white, red  Flesh quality: soluble solids > 12%  Markets: Local, distant

Department of Horticultural Sciences - Texas A&M University State wide testing of selections Variety Bloom Ripe Royal Zest One 600 May 26

Regal 700 May 26

Royal Zest Two 500 June 04

June Gold 650 June 04 Royal Zest Three 550 June 17 Royal Zest Four 600 June 22 Sentinel 750 June 22 Golden Zest 600 June 29 Harvester 750 July 07

Sentinel

GaLa

Royal Zest Two

Sentinel

GaLa

Royal Zest Three Harvester Rich Lady RoyalZest3

RoyalZest4 RoyalZest2 Sentinel

Variety Bloom Ripe WhiteDelOne 550 June 04

WhiteDelTwo 550 June 22

Galaxy 550 June 25

Scarlet Pearl 750 June 26

WhiteDelThree 700 July 07

WhiteDelFour 700 July 14

Late May Chill: 550 Flavor: Subacid

White Delight One Scarlet Pearl

White Delight Two Fairfield

Floresville

White Delight Three White Delight Four Early June

Chill: 550

Flavor: Sweet Acid Variety Bloom Ripe SmTexanOne 550 May 22

SmTexanTwo 550 May 28

SmTexanThree 650 June 04

June Gold 650 June 04

Early May

Chill 350

Flavor Acid Sweet

Smooth Zest One Smooth Zest Two

Late May to Early June

Chill 500

Flavor Sweet Subacid  Royal Zest  Smooth Texan  500-650, Yellow peaches  550-650, Yellow nectarines  Better shape, color, firmness  Late May to early June  Excellent color, flavor  White Delight  550-700, Low acid whites  Smooth Delight  Excellent sweet flavor  400, Nectarines  Early to mid May  Flat Delight  Subacid  500-550, Flat peaches  Subacid flavor  Smooth Zest  350, Nectarines  White Zest  Early May  500, White peach  More to come