Izilawuli zokukhula kwezitshalo zihlanganisa izinhlobo eziningi, ngasinye sinendima yaso ehlukile kanye nobubanzi bokusebenza. Okulandelayo ezinye izilawuli zokukhula kwezitshalo kanye nezici zazo ezibhekwa kabanzi njengezilula ukuzisebenzisa futhi zisebenza kahle:

Izilawuli zokukhula kwezitshalo (ama-PGRs) ziyizinhlanganisela zamakhemikhali ezenziwe ngokuzenzisa ezinemiphumela efanayo yezemvelo kanye nezakhiwo zamakhemikhali ezifanayo njengamahomoni ezitshalo angapheli. Isilawuli sokukhula kwezitshalo siyingxenye ebanzi yezibulala-zinambuzane futhi siyikilasi lezibulala-zinambuzane ezilawula ukukhula nokuthuthuka kwezitshalo, okuhlanganisa izinhlanganisela zokwenziwa ezifana namahomoni ezitshalo zemvelo namahomoni akhishwa ngokuqondile ezintweni eziphilayo.

I-Auxin iyi-indole-3-acetic acid, enefomula ye-molecular C10H9NO2. Yihomoni yokuqala eyatholwa ukukhuthaza ukukhula kwezitshalo. Igama lesiNgisi livela egameni lesiGreki elithi auxein (ukukhula). Umkhiqizo omsulwa we-indole-3-acetic acid iyikristalu emhlophe futhi ayincibiliki emanzini. Incibilika kalula kuzincibilikisi zemvelo njenge-ethanol ne-ether. I-oxidized kalula futhi iphenduka ibebomvu ebomvu ngaphansi kokukhanya, futhi umsebenzi wayo wokuphila nawo uyancipha. I-Indole-3-acetic acid ezitshalweni ingase ibe sesimweni esikhululekile noma esimweni esibophekile (esibophekile).

Umehluko emsebenzini: I-24-epibrassinolide isebenza ngama-97%, kuyilapho i-28-homobrassinolide isebenza ngama-87%. Lokhu kukhombisa ukuthi i-24-epibrassinolide inomsebenzi ophezulu phakathi kwama-brassinolides akhiwe ngamakhemikhali.