STUDIES ON SOME ECOPHYSIOLOGICAL, METABOLIC AND AGRONOMIC ASPECTS OF TREE NUTS

Transcription

1 UNIVERSITA DEGLI STUDI DI PALERMO Dottorato Scienze Agrarie Forestali e Ambientali Dipartimento Scienze Agrarie e Forestali Settore Scientifico Disciplinare AGR/03 STUDIES ON SOME ECOPHYSIOLOGICAL, METABOLIC AND AGRONOMIC ASPECTS OF TREE NUTS IL DOTTORE ADELE AMICO ROXAS IL COORDINATORE CHIA.MO PROF. VINCENZO BAGARELLO IL TUTOR CHIA.MO PROF. TIZIANO CARUSO CO TUTOR CHIA.MO PROF. FRANCESCO P. MARRA CICLO XXIX - ANNO CONSEGUIMENTO TITOLO 2017

2 General introduction Plants harvest the energy of sunlight by converting light energy to chemical energy, products of Calvin cycle are the nonstructural carbohydrates - NSCs (soluble sugars plus starch) - photosynthetic capacity - carbobydrates - yield - alternate bearing SOURCE assimilation allocation utilization NSCs SINK Seeds Fruits Shoot apex Root tips Leaves How improve it agronomic practices

3 Table of contents 1. Effect of different irrigation regimes on ecophysiological parameters of pistachio tree (Pistacia vera L.) 2. Evaluation of photosynthetic parameters of pistachio leaf (Pistacia vera L.) from A/Ci curves analysis 3. Chlorophylls content and volatile compounds in pistachio as affected by different water stress levels 4. Seasonal changes of carbohydrates content in different organs of walnut trees (Juglans regia L.)

4 Introduction Morphological, physiological and biochemical aspects Stomatal closure Leaf intercellular CO 2 concentration Photosynthetic activities Biochemical capacity Oxidative stress processes

5 Farquar photosynthetic model (1980) 1. Rubisco-limited photosynthesis (< 200 ppm) where: V cmax is the maximum velocity of Rubisco for carboxylation; C c is the CO 2 partial pressure at Rubisco; Γ* is the photorespiratory compensation point; R d is respiratory CO 2 release other than by photorespiration (day respiration) and it is presumed to be primarily mitochondrial respiration; K c is the Michaelis constant of Rubisco for carbon dioxide; K o is the inhibition constant (usually taken to be the Michaelis constant) of Rubisco for oxygen; O is the partial pressure of oxygen at Rubisco. 2. RuBP regeneration-limited photosynthesis (> 200 ppm) where: J is the rate of electron transport (at saturated light J is called J max ) 3. Triose phosphate use limitation where: TPU is the rate of use of triose phosphate

6 CO 2 assimilation rate IRRIGATION Alternate bearing Flower buds retention Quality (splitted nuts) Yield

7 Goals 1. Investigate the physiological and agronomic response of mature pistachio trees to three different levels of water supply in order to improve the irrigation management 2. Obtain a first quantitative seasonal estimation of photosynthetic parameters in pistachio trees

8 Location Caltanissetta N, E; altitude 360 m 30-year old Pistacia vera L. trees, cv Bianca P. terebinthus L. rootstock 6.5 x 4.5 m (340 trees ha -1 ) Seasons Materials and methods

9 Irrigation treatments T 0 : rainfed condition (control) T 1 : 50 mm of water supplied (by 1.6 L h -1 emitters) T 2 : 100 mm of water supplied (by 3.5 L h -1 emitters) Day T 1 (mm) T 2 (mm) Day T 1 (mm) T 2 (mm) June June June July June July July July July July July July August July August August August Total Total

10 Meteorological data SIAS - Weather station N, E 0.6 km away from the orchard

11 Plant water status Stem water potential at midday (MPa) Day DAFB Day DAFB May May June 9 47 May June June July 3 71 June July July 4 78 July July August August August August

12 1. Effect of different irrigation regimes on ecophysiological parameters of pistachio tree (Pistacia vera L.) Materials and methods Gas exchanges maximum photosynthetic assimilation rate (A max ) stomatal conductance (g s ) Day DAFB Day DAFB June 9 47 May June June July June July July 4 78 August August August August

13 Yield monitoring flower buds buds drop Phenological stages of nut development (Goldhamer, 1995) Stage 1 Stage 2 Stage 3

14 Stem water potential (Ψ SWP ) Results

15 Maximum assimilation rate (A max )

16 Maximum assimilation rate (Amax) Stomatal conductance (gs) (R²=0.43) (R²=0.29) Stage 1 Stage 2 Stage 3

17 Nut yield Main factors Yield (kg) Fruits /tree CE (kg/cm²) Irrigation treatment T T T significance ns ns ns Year significance * ns ** Flower buds drop T 0 T 1 T % 90% 97% % 83% 72%

18 Conclusions Water relations dynamic, changing throughout the growing seasons and related to the phenological stages Ψ SWP -1.5 MPa threshold to indicate the beginning of severe water stress condition in pistachio trees No effect of irrigation on yields and bud retention Application of obtained information to manage irrigation and improve agricultural water use

19 2. Evaluation of photosynthetic parameters of pistachio leaf (Pistacia vera L.) from A/Ci curves analysis A/Ci curves Materials and methods Cuvette parameters PPFD: 1500 μmol m -2 s -1 temperature: 27 C flow rate: 200 ml min -1 [CO 2 ] 1800 ppm Day DAFB Day DAFB June 9 47 May July June July July 4 78 August August August August [CO 2 ] 5 ppm

20 V cmax - Maximum carboxylation rate allowed by ribulose 1,5 bisphosphate carboxylase/oxygenase Rubisco J max - Rate of photosynthetic electron transport at saturated light TPU - Rate of triose phosphate use R d - Day respiration rate g m - Mesophyll conductance Sharkey et al. (2007) - Photosynthetic model

21 Results Vcmax Jmax

22 Effect of water status on V cmax and J max (R 2 = 0.34)

23 Seasonal patterns of photosynthetic parameters 2014 DAFB TPU (μmol m -2 s -1 ) R d (μmol m -2 s -1 ) g m (μmol m -2 s -1 Pa -1 ) mean S.E mean S.E mean S.E ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mean S.E mean S.E mean S.E ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.08

24 Conclusions Seasonality of maximum rate of RuBP carboxylation (V cmax ) and maximum rate of electron transport (Jmax), on the contrary no clear patterns for triose phosphates (TPU), day respiration (R d ) and mesophyll conductance (g m ) V cmax mean value 146 μmol m -2 s -1, J max mean value 167 μmol m -2 s -1 ; similarity of our data with those about desert species (Wullschleger, 1993) Relationship between stem water potential and V cmax Ψ SWP -1.5 MPa confirmed as transition point between mild and sever stress condition

25 Table of contents 1. Effect of different irrigation regimes on ecophysiological parameters of pistachio tree (Pistacia vera L.) 2. Evaluation of photosynthetic parameters of pistachio leaf (Pistacia vera L.) from A/Ci curves analysis 3. Chlorophylls content and volatile compounds in pistachio as affected by different water stress levels 4. Seasonal changes of carbohydrates content in different organs of walnut trees (Juglans regia L.)

26 Introduction

27 Goals Evaluate the effects of different water stress levels on several qualitative characteristics such as chlorophylls content (a + b), volatile composition and weight of Sicilian pistachio nuts

28 Materials and methods two selected branchlets per tree fresh and dry weight (40 C in a ventilate oven until stable weight) of nuts and kernels

29 Chlorophylls content Chlorophyll a =12.64 A A 647 Chlorophyll b = -5.6 A A 647 Chlorophyll total = 7.04 A A 647 where: -A 664 absorbance at 664 nm -A 647 absorbance at 647 nm (Moran, 1982) N,N-Dimethylformamide

30 Volatile composition Headspace solid-phase microextration mode associated to a gas chromatograph coupled with a mass spectrometer

31 Cumulated stem water potential levels of stress (Gucci et al., 2007) where: MSWPt1 and MSWPt2 are midday stem water potential measured in two consecutive dates; t1 and t2 represent the days when measurements were done. Water stress level 0: cumulated MSWP < -130 MPa Water stress level 1: -130 MPa > cumulated MSWP > -140 MPa Water stress level 2: cumulated MSWP > -140 MPa

32 Results Chlorophylls content Factors Cumulated MSWP (MPa) Chl a (mg/100g) Chl b (mg/100g) Chl tot (mg/100g) Stress level b b b b b ab ab ab a a a a significance *** * * * Year significance ns ns ns ns (R 2 = 0.99)

33 Volatile composition Volatile compounds Alcohols Level 0 Level 1 Level 2 Descriptor Ethanol ns ns sweet 1-Pentanol ns ns sweet 1-Hexanol b a b resin, flower, green 1-Heptanol ns ns mushroom 1-Nonanol ns ns fat, green Esters 2,3-Butanediol, [S-(R*,R*)] ns ns fruit, onion 2,3-Butanediol, [R-(R*,R*)] ns ns fruit, onion Terpenes α-pinene b ab a pine, turpentine Camphene ns ns vanilla β-pinene ns ns pine, resin, turpentine β-myrcene b ab a balsamic, must, spice 3-Carene ns ns lemon, resin p-cymene ns ns solvent, citrus Limonene ns ns citrus, mint 2-Carene ns ns sweet, pine, cedar Hydrocarbons Undecane ns ns alkane Pyrroles 1H-Pyrrole, 1-methyl ns ns alkane

34 Nut characteristics Main factors Nuts/ branchlet (n ) Nut fresh (g) Kernel fresh (g) Nut dry (g) Kernel dry (g) Stress level significance ns ns ns ns ns Year significance *** *** *** *** ***

35 Conclusions Negative effect of the water stress on chlorophylls (a + b) content Seventeen volatile compounds found (mostly terpenes and alcohols) Irrigation improved the sensorial attributes that cause turpentine, resin, green and balsamic aroma of pistachio kernel No effect of irrigation on nut weight

36 Table of contents 1. Effect of different irrigation regimes on ecophysiological parameters of pistachio tree (Pistacia vera L.) 2. Evaluation of photosynthetic parameters of pistachio leaf (Pistacia vera L.) from A/Ci curves analysis 3. Chlorophylls content and volatile compounds in pistachio as affected by different water stress levels 4. Seasonal changes of carbohydrates content in different organs of walnut trees (Juglans regia L.)

37 Introduction Soluble sugars Starch Emergence and growth of new organs Basic metabolic functions Frost resistance Breaking dormancy Flowering Crop yield SOURCE SINK Leaves Shoot apex Root tips Fruits Seeds

38 Goals Monitoring of the seasonal variation of carbohydrates (soluble sugars and starch) in several compartments of walnut trees (Juglans regia L.) depending of the phenological stage

39 Location Davis, California (USA) N, W; 16 m altitude 25-year old Juglans regia L. trees, cv Chandler J. nigra L. rootstock Season 2016 Materials and methods

40 Phenological stages Date sampling Phenological stages 16 March Bud dormancy 29 March Male bloom starting 7 April Bud-break - First leaves out male bloom 15 April Leaves growing 26 April Female bloom expanded leaves 11 May External walnut size growing fully expanded leaves 10 June Internal shell and kernel development increment 11 July Internal shell and kernel development increment 12 August Internal shell and kernel development increment 7 September Hulls split 7 October Harvest time leaves senescence beginning

41 Samples Carbohydrates extraction NSCs soluble sugars starch Organs: Root Rootstock Stem Limb Branchlets basal / apical wood / bark anthrone Standard curve

42 Results

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44 Conclusions Non-structural carbobydrates concentration (soluble sugar plus starch) change throughout the growing season and depends on the tissue organs Mobilization of starch is essential to interrupt the bud-dormancy and support growth and metabolism of new organs formation Carbohydrates depletion resulted dynamic throughout the season and strongly related to the phenological stages

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