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 of % 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 .