How does carbohydrate supply limit flower development in grape and kiwifruit vines? Annette Richardson
Introduction» Why study this?» Structure of this talk:» Growth patterns and carbohydrate supply» Carbohydrate supply during flower development» Inflorescence initiation» Early flower development» Late flower development
Growth patterns of grape and kiwifruit are very similar Root growth Fruit growth Shoot growth Root growth Kiwifruit Grape» Fruit growth competes with shoot and root growth» Root growth is greater in kiwifruit Fruit growth Shoot growth 0 50 100 150 200 250 Days after budbreak
Carbohydrate reserves support shoot growth in spring Carbohydrate concentration (mg gdw -1 ) 100 80 60 40 20 0 200 150 100 50 Kiwifruit Grape root wood root wood» Root and wood reserves decrease from late winter until early summer» Increase summer/autumn 0 0 100 200 300 Days after budbreak
Photosynthesis increases during spring» Shoots self supporting 3 Kiwifruit 30-40 days after budbreak» Peak photosynthesis rates at the end of shoot growth Carbon acquisition (g C /shoot /day) 2 1 0 1.5 1.0 0.5 Grape 0.0 0 50 100 150 200 Days after budbreak
Flower development occurs over two seasons Year 1 Year 2 Morphogenesis of flowers Initiation of meristems Budbreak Flowering Fruit development Dormancy
Treatments to alter carbohydrate (CHO) supply Shade CHO Photosynthesis Girdle spring -CHO Transport in Girdle autumn +CHO Transport out
Flower initiation in spring Year 1 not affected by carbohydrate supply» Carbohydrate supply did not affect the number of inflorescence meristems that were initiated» Carbohydrate supply affected shoot growth Inflorescence per bud 1.0 0.5 0.0 1.0 0.5 0.0 Kiwifruit Grape Untreated Girdle Girdle + shade Treatment
Carbohydrate reserves stored in autumn affect inflorescence numbers in early spring» Autumn shade reduced inflorescence number in spring 0.8 Kiwifruit» Kiwifruit reserves 22% lower» Grape reserve 35% lower Inflorescence per bud 0.6 0.4 0.2 0.0 0.8 Grape 0.6 0.4 0.2 0.0 Exposed Exposed girdle Shade intact Shade girdle Treatment
Reduced carbohydrate supply in late spring reduces flower numbers and yield» Reduced flower numbers and fruitset» Shaded shoots performed poorly over the season Bunch weight (g) Yield shoot -1 (g) 500 400 300 200 100 0 300 250 200 150 100 50 0 Kiwifruit Grape Shade Shade/Girdle Exposed Exposed/Girdle Treatment
Does carbohydrate supply limit flower development in grape and kiwifruit vines?» Carbohydrate supply limits flower development and yield in grape and kiwifruit» Flowers initiated during shoot growth in spring Year 1 are not directly limited by carbohydrate supply» Reserves stored in summer and autumn Year 1 are essential for early flower and shoot development in spring Year 2» Carbohydrate supply also affects later flower development and fruit set in Year 2
Take home messages for vine management» Shoot growth, flower development, fruit growth, root growth and storage of reserves all compete for carbohydrate supply» Good canopy development and shoot growth in spring are essential to supply both this years and next years crop» Maintaining an open canopy and healthy leaves ensures photosynthesis is optimised to support the vine and store reserves to make next seasons flowers and shoots
Acknowledgements» Supervisors Dr Dennis Greer, Dr Bruno Holzapfel and Dr Ross Atkinson» Management and staff of Marsden Estate, Ivana Wines and Kerikeri Research Centre» Technical expertise provided by Helen Boldingh and Peggy Kashuba» CSU postgraduate scholarship and Plant and Food Research
www.plantandfood.co.nz Annette.Richardson@plantandfood.co.nz