Flowering and germination physiology on C4 grasses. Ing. Agr. Mónica I. Moreno Instituto Nacional de Semillas - Argentina
Morphology and Flowering Plant Estructure
Inflorescence Estructure
Reproduction Sexual REPRODUCTION Chloris gayana Chloris gayana diploides: cv Pionner, cv Finecut, cv Top cut, cv Katambora Chloris gayana tetraplyodes: cv Callide, cv Epica Setaria anceps Cv Narok Cv Splenda
REPRODUCTION APOMICTIC REPRODUCTION Cenchrus ciliaris cv texas cv biloela cv molopo HibrYDS OF Cenchrus ciliaris. Brachiaria decumbens Brachiaria brizantha Brachiaria humidicola SEXUAL: Brachiaria ruziziensis y Brachiaria mutica Panicum maximun ( puede haber sexualidad limitada) Cv gatton Cv tanzania Cv colonial Cv tobiata Cv mombaza Hbridos cv vencedor y centenario ( some crossing)
Flowering and Fructification Differentiation of spikelets and floral parts. Process Duration Anthesis stepped Drought effect during anthesis.
Flowering and Fructification Caryopsis Development: In Brachiaria the caryopsis is covered by hard and rigid estructures, This is the different with Chloris y Cenchrus Relationship between the development of abscition layer and the caryopsis maturity. In Panicum and Brachiaria the maduration lapse of time 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 Fructification 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 crops. The abscission is very common in Brachiaria, Panicum, Cenchrus and Chloris. 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 Production 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 pasture Tipical development Pattern of tropical pasture tillers
C - 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 environments
TEMPERATURE AND LIGHT OVER THE PHOTOSYNTHESIS RATE IN C3 AND C4 PLANTS. 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 CONTROL LEAVES PERCEIVES THE PHOTOPERIOD DURATION AND MAKES A SEGNAL THAT IS TRANSMITED TO THE APICAL MERISTEM. 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. IN ARGENTINA AND QUEENSLAND FLOWERING RECEN WITHOUT RESTRICTION DURING ALL THE SUMMER AND EVEN CAN PRODUCE TWO HARVEST IN ONE YEAR.
Good condition in the seed Night Temperature up to 16ªC The pollen remain viable only few hours.
HARVEST EFFICIENCY
HARVEST EFFICIENCY
SEED DORMANCY Factors that t facilitate t dormancy: Hard seedcoat Seedcoat with water impermeability Presence of inhibitor in the seed coat. Embryo Under-development. Precense of Inhibitor. Several comnination of factors.
Panicum maximun CV GATTON: HIGH PERCENTAGE OF DORMAN SEEDS AFTER THE HARVEST. THE TETRAZOLIUM TEST ES THE BEST TOOL FOR QUALITY CONTROL IN THIS MOMENT. THE PERCENTAGE OF DORMAN SEED IS VARIABLE AND DEPEND OF THE ENVIRONMENT AND THE HARVEST. THE GERMINATION INCREASE DURING THE STORAGE AND BEGIN TO DECLINE AFTER 2 YEARS. THE SEED DRY CONDITIONS AFTER THE HARVEST HAS INFLUENCE OVER THE SEED QUALITY. HIGH VARIABILITY IN THE EMBRYO MADURATION. THE FLORWERING SYNCHRONIZATION IS THE KEY FOR THE GOOD QUALITY SEED.
Choloris gayana DORMANCY 2 3 MONTH RESPONSE TO NO3K SEED QUALITY VARIABLE WITH THE METHOD USING DURING HARVEST.
Cenchrus ciliaris HIGH PERCENTEGE OF DORMAN SEED AFTER THE HARVEST. PRESENCE 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 High percentage of dormancy in seed immediatelly after harvest. Has phisical dormancy due to the tissue hardness that cover the seed (lemma and palea) and physiological dormancy too. The treatment with sulfuric acid promove germination breaking the phisical dormancy. The phisiological dormancy decrease with the age of the seed.
Final Considerations THE PRODUCTION OF TROPICAL AND SUBTROPICAL SEED IS AN SPECIALITY ACTIVITY. 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 CHARACTERISTIC.
Brachiaria humidicola and Panicum maximun Ing. Agr. Mónica I. Moreno Instituto Nacional de Semillas - Argentina
Brachiaria
Brachiaria sp. Spickelets two-flowered, where only the up flower is well developed and fertile. In the lower flower, only remains the sterile lemma with aspect of glums. Spickelets are glabrous ó with few pubescence. Are disposed in two row to the rachis.
PSD 36 (8 genera with 24 species) Axonopus ( 2 ) Brachiaria (5) Digitaria (1) Melinis ( 1) Panicum (6) Paspalum (6) Setaria ( 2) Urochloa (1)
P.S.D. Nro. 36 C Spikelets, with glumes, lemma and palea enclosing a caryosis, plus attached sterile lemma. Floret, with lemma and palea enclosing a caryopsis. Caryopsis. Piece of caryopsis larger than one-half the original i size. Panicum and Digitaria: no need to ckeck for the presence of a caryospis.
Brachiaria humidícola
Brachiaria decumbens
Brachiaria mutica
Brachiaria ramosa
Brachiaria ruziziensis
Brachiaria brizantha (no includes in the Brachiaria brizantha (no includes in the ISTA Rules, yet??)
Panicum maximun
Panicum S i k l t ith t thi d l Spickelets with two thin and papery glumes, a sterele lemma of like exture, and a fertile floret.
Panicum The lemmas and paleas of the fertile florets are stiff and hard, or at least firmer than the glumes and sterile lemmas. In commerciual samples: the units may be an entire spikelet or only the fertile floret.hulled -out caryopses are present accasionally.
Others genus included in PSD 36
Anoxopus compressus
Axonopus fissifolius
Melinis minutifolia
Paspalum dilatatum
Paspalum notatum t
Brachiaria plantaginea
Chloris gayana Ing Agr Mónica I Moreno Ing. Agr. Mónica I. Moreno Instituto Nacional de Semillas - Argentina
Chloris spp Spikelets of Chloris are several-flowered, and disarticulate t above the glumes. The lowe flower of the spikelet is sessile and perfect, the upper florets aresterile. Sterile flowerts consist of empty py lemmas, and if more than one is developed the smaller ones are often enclosed in the lower, producing an inflated wedge- shaped rudiment. The spikelets without the glumes is the units ussually considered the seed
Spikelets in one-sided, with one or more rudimentary florets disposed d in two rows.
Each spikelets has basal florets and two or p more sterile upper florets.
The lemmas are compressed laterally, with a shallow groove between the keel and marginal nerves. In Chl. gayana the keel nerves are glabrous or sparsely pubescent; awn of rudiment shorter than the awn of ferile floret
PSD Nro. 42 C Spikelets, with glumes enclosing a caryopsis with or without hyaline palea or lemmas,rachis segments(s), pedicel (s), awns(s), attached sterile or fertile floret(s). Floret, with lemma and palea,with or without awn. Caryopsis Piece of caryopsis larger than one-half the original size. (Bouteloua, Chloris: no need to ckeck for the presence of caryopsis)
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