Fl i d i tiFlowering and germination physiology on C4 grassesphysiology on C4 grasses.

Ing. Agr. Mónica I. MorenoInstituto Nacional de Semillas - Argentina

Morphology and FloweringMorphology and Flowering

Plant Estructure

Inflorescence Estructure

ReproductionReproduction• Sexual REPRODUCTION• Sexual REPRODUCTION• Chloris gayana

Chloris gayana diploides: cv Pionnercv Pionner,cv Finecut,cv Top cut,cv Katamboracv Katambora

Chloris gayana tetraplyodes:cv Callide,,cv Epica

• Setaria anceps• Cv Narok• Cv Splenda

REPRODUCTIONREPRODUCTIONAPOMICTIC REPRODUCTIONAPOMICTIC REPRODUCTION• Cenchrus ciliaris

cv texascv biloelacv molopo

HibrYDS OF Cenchrus ciliaris.

• Brachiaria decumbens• Brachiaria decumbensBrachiaria brizanthaBrachiaria humidicola

SEXUAL: Brachiaria ruziziensis y Brachiaria mutica

• Panicum maximun ( puede haber sexualidad limitada)Cv gattonCv gattonCv tanzaniaCv colonialCv tobiataCv mombazaHbridos cv vencedor y centenario ( some crossing)

Flowering and Fructificationg

• Differentiation of spikelets and floral parts.p p

• Process Duration• Process Duration

• Anthesis stepped

• Drought effect during anthesis.

Flowering and FructificationFlowering and Fructification

Caryopsis Development:Caryopsis Development:

• In Brachiaria the caryopsis is covered by hard and rigid estructures This is the different with Chloris y Cenchrusestructures, This is the different with Chloris y Cenchrus

Relationship between the development of abscition layer and the caryopsis maturitythe caryopsis maturity.

• In Panicum and Brachiaria the maduration lapse of time depends on the enviromental conditions while the rate of depends on the enviromental conditions while the rate of development of the abscicion layer is relatively constant.

• When the abscition is previous to the maduration a high • When the abscition is previous to the maduration a high percentage of inmature seeds is getting.

Flowering and Fructificationg

• The variation on inmature seeds content is one important cause or reason in the differents between the seed quality in differents areas and /or differents time in cropsquality in differents areas and /or differents time in crops.

• The abscission is very common in Brachiaria Panicum• The abscission is very common in Brachiaria, Panicum, Cenchrus and Chloris.

• One or two weeks after the emergent of the bunch• One or two weeks after the emergent of the bunch, beging the reproductive phase.

• The proportion of bunch that produce flowering heads depend on the fertility level in the soil, especially the N content.

Tillering and Seed ProductionTillering and Seed Production• The crops for seed production are essencialy tillers communities• The crops for seed production are essencialy tillers communities

that developing in the direction of flowering head productions for the harvest.

• The crops must be carefully handle looking for a synchronize flowering.

• The maximun seed production depend of get the maximun number of trillers that produces inflorecence at the same time. (LOCH, 1985))

• The rate of trillers is maxima after the cut or a defoliation.

Tipical development Pattern of tropical pastureTipical development Pattern of tropical pasture tillers

C Fixation on C 4 GrassesC - Fixation on C 4 Grasses

• Comparison between the leaf anatomy in C3 and C4 plants and the relation with the metabolism.

The C4 in Tropical environmentsThe C4 in Tropical environments

TEMPERATURE AND LIGHT OVER THE PHOTOSYNTHESIS RATE IN C3 AND C4PHOTOSYNTHESIS RATE IN C3 AND C4

PLANTS.IN HIGHT TEMPERATURA CONDITIONS THE C4 PLANTS HAS• IN HIGHT TEMPERATURA CONDITIONS THE C4 PLANTS HAS BETTER ALTERNATIVE THAN THE C3 .

• THE C4 HAS MORE EFFICIENCY IN THE WATER USE.

FLOWERING AND ENVIRONMENT CONTROLCONTROL

LEAVES PERCEIVES THE PHOTOPERIOD DURATION AND• LEAVES PERCEIVES THE PHOTOPERIOD DURATION AND MAKES A SEGNAL THAT IS TRANSMITED TO THE APICAL MERISTEM.Chl i TETRAPLOYDE LIKE CALLIDE EPICA AND• Chloris gayana TETRAPLOYDE LIKE CALLIDE, EPICA AND BOMA ARE SHORT DAY PLANTS

• The CV. Diploid of Chloris gayana (FINE CUT, KATAMBORA AND PIONNER) and Panicum maximun are short or mediun day when grows in experimental envionremts under controled condiction.g p

• IN ARGENTINA AND QUEENSLAND FLOWERING RECEN WITHOUT RESTRICTION DURING ALL THE SUMMER ANDWITHOUT RESTRICTION DURING ALL THE SUMMER AND EVEN CAN PRODUCE TWO HARVEST IN ONE YEAR.

Good condition in the seedGood condition in the seed

Ni ht T t t 16ªC• Night Temperature up to 16ªC

The pollen remain viable only few hours.

HARVEST EFFICIENCYHARVEST EFFICIENCY

HARVEST EFFICIENCY

SEED DORMANCY

F t th t f ilit t dFactors that facilitate dormancy:Hard seedcoatSeedcoat with water impermeability Presence of inhibitor in the seed coatPresence of inhibitor in the seed coat.Embryo Under-development.Precense of Inhibitor.Several comnination of factorsSeveral comnination of factors.

Panicum maximun CV GATTON:

• HIGH PERCENTAGE OF DORMAN SEEDS AFTER THE HARVEST.

• THE TETRAZOLIUM TEST ES THE BEST TOOL FOR QUALITY • THE TETRAZOLIUM TEST ES THE BEST TOOL FOR QUALITY CONTROL IN THIS MOMENT.

• THE PERCENTAGE OF DORMAN SEED IS VARIABLE AND O O SDEPEND OF THE ENVIRONMENT AND THE HARVEST.

• THE GERMINATION INCREASE DURING THE STORAGE AND BEGIN TO DECLINE AFTER 2 YEARSBEGIN TO DECLINE AFTER 2 YEARS.

• THE SEED DRY CONDITIONS AFTER THE HARVEST HAS INFLUENCE OVER THE SEED QUALITY.Q

• HIGH VARIABILITY IN THE EMBRYO MADURATION.

• THE FLORWERING SYNCHRONIZATION IS THE KEY FOR THE GOOD QUALITY SEED.

Choloris gayanaCholoris gayana• DORMANCY 2 – 3 MONTHO C 3 O

• RESPONSE TO NO3K

• SEED QUALITY VARIABLE WITH THE METHOD USING DURING HARVESTMETHOD USING DURING HARVEST.

Cenchrus ciliaris

HIGH PERCENTEGE OF DORMAN SEED AFTER THE HARVEST• HIGH PERCENTEGE OF DORMAN SEED AFTER THE HARVEST.

• PRESENCE OF INHIBITOR IN THE FRUITPRESENCE OF INHIBITOR IN THE FRUIT.

• THE TETRAZOLIUM TEST IS A GOOD INDICATOR OF THE QUALITY SEED.

• DIFERENCE IN THE PERCENTEGE OF FRUIT CONTAINING• DIFERENCE IN THE PERCENTEGE OF FRUIT CONTAINING CARYOPSIS IN THE DIFFERENTS CULTIVAR.

BRACHIARIA BRIZANTHA

Hi h t f d i d• High percentage of dormancy in seed immediatelly after harvest.

• Has phisical dormancy due to the tissue• Has phisical dormancy due to the tissue hardness that cover the seed (lemma and palea) and physiological dormancy toopalea) and physiological dormancy too.

• The treatment with sulfuric acid promove germination breaking the phisical dormancy.germination breaking the phisical dormancy.

• The phisiological dormancy decrease with the age of the seed. g

Final ConsiderationsFinal Considerations

• THE PRODUCTION OF TROPICAL AND SUBTROPICAL • THE PRODUCTION OF TROPICAL AND SUBTROPICAL SEED IS AN SPECIALITY ACTIVITY.

• TO GET GOOD QUALITY SEED IS RELATED WITH THE • TO GET GOOD QUALITY SEED IS RELATED WITH THE CROP PHISIOLOGY AND SEED UNDERSTANDING.

• THE VEGETAL IMPROVEMENT(BREEDING) MUST CONSIDER THE CAPACITY OF PRODUCTION OF GOOD QUALITY SEED AND TO OBTEIN GOOD AGRONOMIC QUALITY SEED, AND TO OBTEIN GOOD AGRONOMIC CHARACTERISTIC.

““Brachiaria humidicolaandand

Panicum maximun”

Ing. Agr. Mónica I. MorenoInstituto Nacional de Semillas - Argentina

“ ”“Brachiaria”

Brachiaria sp.• Spickelets two-flowered, where only the up

flower is well developed and fertileflower is well developed and fertile.• In the lower flower, only remains the sterile

lemma with aspect of glums.• Spickelets are glabrous ó with fewSpickelets are glabrous ó with few

pubescence. Are disposed in two row to therachisrachis.

PSD 36(8 genera with 24 species)

• Axonopus ( 2 )Brachiaria (5)• Brachiaria (5)

• Digitaria (1)g ( )• Melinis ( 1)

P i (6)• Panicum (6)• Paspalum (6)p ( )• Setaria ( 2)

U hl (1)• Urochloa (1)

P.S.D. Nro. 36 “C” • Spikelets, with glumes, lemma and palea enclosing ap , g , p g

caryosis, plus attached sterile lemma.• Floret with lemma and palea enclosing a caryopsisFloret, with lemma and palea enclosing a caryopsis.• Caryopsis.

Pi f i l th h lf th i i l• Piece of caryopsis larger than one-half the originalsize.

• Panicum and Digitaria: no need to ckeck for thepresence of a caryospis.

• Brachiaria humidícola

• Brachiaria decumbens

• Brachiaria mutica

• Brachiaria ramosa

• Brachiaria ruziziensis

• Brachiaria brizantha (no includes in theBrachiaria brizantha (no includes in the ISTA Rules, yet ??)

“ ”“Panicum maximun”

PanicumPanicum S i k l t ith t thi d l• Spickelets with two thin and papery glumes, asterele lemma of like exture, and a fertile floret.

PanicumPanicum Th l d l f th f til fl t• The lemmas and paleas of the fertile florets arestiff and hard, or at least firmer than the glumes

d t il land sterile lemmas.• In commerciual samples: the units may be an

entire spikelet or only the fertile floret.Hulled -outcaryopses are present accasionally.

Others genus included in PSDOthers genus included in PSD 36

Anoxopus compressus

Axonopus fissifoliusp

Melinis minutifoliaMelinis minutifolia

Paspalum dilatatumPaspalum dilatatum

P l t tPaspalum notatum

• Brachiaria plantaginea

“Chloris gayana”

Ing Agr Mónica I MorenoIng. Agr. Mónica I. MorenoInstituto Nacional de Semillas - Argentina

Chloris spp

• Spikelets of Chloris are several-flowered,d di ti l t b th l Thand disarticulate above the glumes. The

lowe flower of the spikelet is sessile andf t th fl t t ilperfect, the upper florets are sterile.

• Sterile flowerts consist of empty lemmas,p y ,and if more than one is developed thesmaller ones are often enclosed in thesmaller ones are often enclosed in thelower, producing an inflated wedge-shaped rudiment The spikelets without theshaped rudiment. The spikelets without theglumes is the units ussually considered theseed

• Spikelets in one-sided, with one or more di t fl t di d i trudimentary florets disposed in two rows.

• Each spikelets has basal florets and two orpmore sterile upper florets.

• The lemmas are compressed laterally with• The lemmas are compressed laterally, witha shallow groove between the keel andmarginal nerves.

• In Chl. gayana the keel nerves areglabrous or sparsely pubescent; awn ofg p y p ;rudiment shorter than the awn of ferilefloret

PSD Nro. 42 “C”• Spikelets, with glumes enclosing a g g

caryopsis with or without hyaline palea or lemmas,rachis segments(s), pedicel (s), , g ( ), p ( ),awns(s), attached sterile or fertile floret(s).

• Floret with lemma and palea with or• Floret, with lemma and palea,with or without awn.C• Caryopsis

• Piece of caryopsis larger than one-half the y p goriginal size.

• (Bouteloua Chloris: no need to ckeck for• (Bouteloua, Chloris: no need to ckeck for the presence of caryopsis)

ThankThank