Net photosynthesis (A) of bell pepper Net photosynthesis (A) of bell pepper during peak drought & recoveryduring peak drought & recovery

AMF Enhancement of Drought StressAMF Enhancement of Drought Stress--Bell PepperBell Pepper

AMF Peppers have:AMF Peppers have:Leaf ChlorophyllLeaf Chlorophyll

Stomatal ConductanceStomatal Conductance

PhotosynthesisPhotosynthesis

Osmotic AdjustmentOsmotic Adjustment

Faster Drought RecoveryFaster Drought Recovery

Phosphorus & plant size Phosphorus & plant size not not the limiting factorthe limiting factor

AMF Pepper Plants have:AMF Pepper Plants have:••Greater Extraradical Hyphae formationGreater Extraradical Hyphae formation

••Greater Soil AggregationGreater Soil Aggregation

•Improved Soil Tilth

•Glomalin – hydrophobic protein

→→ Not all mycorrhiza respond equally to droughtNot all mycorrhiza respond equally to drought

Chile ancho pepper: Chile ancho pepper:

••Glomus fasciculatumGlomus fasciculatum (Trappe, Oregon) (Trappe, Oregon)

••ZACZAC--1919: : mixed mixed Glomus Glomus species: species: G. albidiumG. albidium, , G. claroidesG. claroides, , G. diaphamumG. diaphamum

(Zacatecas, Mexico; 450 mm annual Precipitation; (Zacatecas, Mexico; 450 mm annual Precipitation; Chamizo, FerreraChamizo, Ferrera--Cerrato, 1998)Cerrato, 1998)

AMF Drought Soil Moist.(%)

ψleaf

(-Mpa)

gs

(mmol m-2

s-1)

RWC

(%)

Whole Plant Transpiration(mg H2O

m-2 s-1)

WUE(10-3. g. kg-1)

∆(‰)

Control No 17.0±1.4 0.1±0 268±14 92.6±1.4 48.2±1.4 5.34 18.9G. fasc. 18.3±0.4 0.1±0 257±13 88.9±1.1 48.1±1.4 5.29 18.7

ZAC-19 18.8±0.2 0.1±0 233±19 93.0±1.9 46.7±2.1 5.09 18.8

Control Yes 3.9±0.1 0.7±0.1 57±7 80.2±3.4 30.1±1.7 5.55 19.1G. fasc. 3.8±0.1 0.8±0.1 46±4 79.3±1.0 27.1±1.6 5.68 19.2

ZAC-19. 4.1± 0.4 0.2±0 51±4 84.4±1.9 25.4±1.9 5.58 19.2

SignificanceAMF NS 0.0001 NS NS NS NS NSDrought (D) 0.0001 0.0001 0.0001 0.0001 0.0001 NS NSAMF X (D) NS 0.0001 NS NS NS NS NS

Chile Ancho pepper plants during peak drought stress (day 20).Chile Ancho pepper plants during peak drought stress (day 20).

AMF Drought % Plantsnot wilted

% Plants moderatelywilted

% Plantsseverely wilted

Control Yes 0±0 47±12. 53±12

G. fasc. 0±0 26±10 74±10ZAC-19. 0±0 79±10 21±11

SignificanceAMF NS 0.0026 0.0089Drought (D) 0.0001 0.0001 0.0001AMF x D NS 0.0026 0.0089

Wilting of Chile Ancho pepper plants Wilting of Chile Ancho pepper plants ---- peak drought stress (day 20).peak drought stress (day 20).

Effect of Drought Stress on Colonization of Chile Ancho pepperEffect of Drought Stress on Colonization of Chile Ancho pepper

Control Glomus Glomus fasciculatumfasciculatum ZacZac--1919

DroughtDrought

NoNo 00 56.4a56.4a 37.5b

YesYes 00 21.6b21.6b 43.0a

(Pr>F)(Pr>F) NSNS 0.00010.0001 NSNS

DroughtDrought

NoNo 00 81.4a81.4a 29.9

YesYes 00 42.8b42.8b 26.1

(Pr>F)(Pr>F) NSNS 0.00010.0001 NSNS

DroughtDrought

NoNo 00 90.2a90.2a 51.9b

YesYes 00 62.7b62.7b 59.9a

(Pr>F)(Pr>F) NSNS 0.00010.0001 0.0030.003

% Arbuscule Formation

% Vesicle Formation

% Total Root Colonization

Neem (Azadirachta indica)

Glomus intraradicies

Vesicles

Appressorium

Table 2.Table 2. Growth parameters of mycorrhizal (AMF) and NonGrowth parameters of mycorrhizal (AMF) and Non--VAM VAM neem plants at the end of the drought stress cycle neem plants at the end of the drought stress cycle (23 days of drought followed (23 days of drought followed by a 1 day recovery).by a 1 day recovery).

AMF AMF DroughtDroughtacclimationacclimation

LeafLeafNo.No.

Leaf Leaf areaarea

Plant dry mass (g)Plant dry mass (g) Root/Root/shootshootratioratio

(m(m22))LeafLeaf(g) (g)

StemStem(g)(g)

RootRoot(g)(g) (g.g(g.g--11))

NonAMFNonAMF

AMFAMF

SignificanceSignificanceAMFAMFDroughtDroughtAMF x DAMF x D

NoNoYesYesNoNoYesYes

2929±±222121±±222929±±222323±±22

NSNS****NSNS

0.200.20±±0.010.010.140.14±±0.010.010.200.20±±0.010.010.140.14±±0.010.01

NSNS****

NSNS

1818±±111111±±111818±±111212±±11

NSNS****

NSNS

1111±±1188±±11

1111±±0099±±11

NSNS****

NSNS

1111±±1199±±00

1212±±1199±±00

NSNS****

NSNS

0.380.38±±0.030.030.470.47±±0.030.030.400.40±±0.020.020.430.43±±0.030.03

NSNS****

NSNS

AMF Effects on Neem Tree SeedlingsAMF Effects on Neem Tree Seedlings

±± AMF neem trees of similar size and nutrition respond to drought AMF neem trees of similar size and nutrition respond to drought similarly.similarly.

Neem drought response: decrease in leaf area, gas exchange rate Neem drought response: decrease in leaf area, gas exchange rate and water and water relations parameters. relations parameters.

Rapid recovery after rehydration with an acclimation of stomatalRapid recovery after rehydration with an acclimation of stomatal conductance.conductance.

Water Use EfficiencyWater Use Efficiency

Dry Mass gain per total water usage Dry Mass gain per total water usage ––(g Carbon/kg H(g Carbon/kg H22O) O) [Long Term][Long Term]

Gas Exchange: net Photosynthesis/ stomatal Gas Exchange: net Photosynthesis/ stomatal conductance conductance ((AA) / () / (ggss) ) [Instantaneous][Instantaneous]