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Growth irreversible increase
in volume– cell expansion driven by turgor pressure– sum of local cell expansions
Measures of plant growth
increase in cell volume
increase in dry weight
increase in cell number
(unicellulars)
fractional change in length per unit time. magnitude and location of extension rate
r = (1/L)(dL/dt).
Relative elemental growth
rate
Pertumbuhan & Perkembangan
PERTUMBUHAN • Yaitu proses pertambahan jumlah,
bentuk, ukuran serta fungsi sel akibat adanya pembelahan sel.
• Bersifat kuantitatif, dapat diukur dengan suatu alat ukur tertentu, serta dapat terlihat secara fisik.
• Bersifat irreversibel • Untuk tanaman dapat diukur dengan
Auksanometer (busur tumbuhan pada tanaman). Untuk manusia dan hewan dengan menggunakan alat ukur yang beragam.
PERKEMBANGAN • Yaitu proses menuju kedewasaan
(kematangan pada sel). • Bersifat kualitatif dan tidak dapat
diukur dengan suatu alat. • Ditandai dengan berfungsinya alat-alat
reproduksi pada makhluk hidup. • Untuk tanaman dengan keluarnya
bunga serta buah. Untuk manusia dan hewan dengan mulai berfungsinya alat reproduksi yaitu menghasilkan sel gamet jantan (sperma) dan sel gamet betina (ovum), serta melangsungkan keturunan.
Pertumbuhan & Perkembangan
The Growth Hormones
IAAs and compounds of same
biological activities – promote cell elongation– promote cell division– form adventitious roots
shoot apical meristems young leaves developing fruits and seeds all parts of plant
Synthesis sites of IAA
Concentrations of IAA in different regions of the shoot of a wild-type tobacco plant. The bars at the different regions indicate the auxin concentrations found in leaves and stems. (After Sitbon et al. 1991.)
Apical dominanceInhibition of the growth of lateral buds
by growing apical bud Maintain cell viability
delay in the onset of leaf abscision regulation of the floral bud development promotion of fruit development
Penyembuhan luka dan keterlibatan
auxin
Auxin
Pengembangan selPhototropismeGeotropismeApical dominasiPertumbuhan akar (root initiation)ParthenocarpyAbisissionPembentukan callus (callus formation) danRespirasi Pengembangan sel
Gibberellins
stimulate stem elongation by stimulating cell division and elongation
stimulates bolting/flowering in response to long days
breaks seed dormancy in some plants which require stratification or light to induce germination
stimulates enzyme production (a-amylase) in germinating cereal grains for mobilization of seed reserves
can cause seedless (parthenocarpic) fruit development
can delay senescence in leaves and citrus fruits
Gibberelins
• Difference between Auxin & Gibberellin:
AUXIN GIBBERELLIN
regulates elongation in grass seedlings and herbs
controls elongation in the mature regions of trees and shrubs
stimulates only cellular elongation
stimulates cell division and elongation
Can NOT tolerate high levels of auxin
can tolerate high levels of gibberellin
has more of an effect on roots
has little effect on roots
Cytokinins• Found in active dividing
structures, seeds, fruits, leaves and root tips
• Central to tissue culture methods and extremely important in biotech.
• modifying apical growth.• The cytokinin/auxin ratio
regulates the production of roots and shoots in tissue cultures
AUXIN VS CYTOKININAuxins: • - They are produced in the apical part of
the plant.- They prevent the development of the axillary buds. - They favour the rhizogenesis ...(development of roots).
Cytokinins: • - They are produced in the roots.
- They prevent the development of roots.- They favour the development of the axillary buds.
Ethylene
• Plays a role in fruit ripening• Promotes abscission (shedding of leaves,
flowers and fruit)– Triggers enzymes that promote fruit
loosening from trees
Auxin prevents abscission (prevents preharvest)
High concentration does the opposite
Abscisic Acid (ABA)• First discovered as dormin and abscisin• Dormin ash and potatoes• In other plants abscisin• Identical compounds now called Abscisic
acid• Levels increase during early seed
development• Stimulates the productio of seed storage
protein• Prevents premature seed germination• Decline in ABA leads to germination