Izitshalo ziye koloni iningi ebusweni bomhlaba. Ngakho siyini isihluthulelo sempumelelo yabo?
Abantu bavame ukucabanga ngezitshalo njengezinto eziphilayo ezilula, ezingenangqondo. Bangase bahlale begxilile endaweni eyodwa, kodwa lapho ososayensi befunda okwengeziwe ngezitshalo, eyinkimbinkimbi futhi esabelayo siyaqaphela ukuthi banjalo. Zinhle kakhulu ekuzivumelaniseni nezimo zendawo. Izitshalo zingochwepheshe, zisebenzisa kakhulu lokho okuseduze nalapho zimila khona.
Ukufunda ngobunkimbinkimbi bempilo yezitshalo kungaphezu kokukhuthaza abantu. Ukufunda izitshalo nakho kumayelana nokwenza isiqiniseko sisakwazi ukutshala izitshalo esikhathini esizayo njengoba ukushintsha kwesimo sezulu kwenza isimo sezulu sethu sibe sibi kakhulu.
Izimpawu zemvelo zilolonga ukukhula nokuthuthukiswa kwezitshalo. Isibonelo, izitshalo eziningi zisebenzisa ubude bosuku njengenkomba ukuqala ukuqhakaza. Ingxenye efihlekile yezitshalo, izimpande, nazo zisebenzisa izimpawu ezivela endaweni ezizungezile ukuze kuqinisekiswe ukuthi ukuma kwazo kulungiselelwe ukuze kudliwe amanzi kanye nemisoco.
Izimpande zivikela izitshalo zazo ekucindezelekeni njengesomiso ngokushintsha isimo sazo (igatsha ukuze kwandiswe indawo engaphezulu, isibonelo) ukuthola amanzi engeziwe. Kodwa kuze kube muva nje, asizange siqonde ukuthi izimpande zizwa kanjani ukuthi amanzi ayatholakala enhlabathini ezungezile.
Amanzi yi-molecule ebaluleke kakhulu emhlabeni. Okuningi noma okuncane kakhulu kungalimaza i-ecosystem. Umthelela omubi wokuguquka kwesimo sezulu (njengoba kusanda kubonakala eYurophu nasempumalanga ye-Afrika) uyawenza kokubili izikhukhula kanye nesomiso kuvame kakhulu. Kusukela ukushintsha kwesimo sezulu is ukwenza amaphethini emvula iya ngokuya ishintshashintsha, ukufunda indlela izitshalo ezisabela ngayo ukushoda kwamanzi ibalulekile ekwenzeni izitshalo zikwazi ukumelana nokuqina.
Ithimba lethu lososayensi bezitshalo nomhlabathi kanye nezibalo okusanda kutholwa Kanjani izimpande zezitshalo guqula isimo sazo ukuze kwandiswe ukumuncwa kwamanzi. Izimpande zivame ukuhluma ngokuvundlile. Kodwa ziyama i-branching lapho zilahlekelwa ukuthintana namanzi (njengokukhula ngegebe eligcwele umoya enhlabathini) futhi izimpande ziphinde ziqale kabusha uma sezixhumene nomhlabathi oswakeme.
Ithimba lethu lithole ukuthi izitshalo zisebenzisa uhlelo olubizwa ngokuthi i-hydrosignalling ukuphatha lapho izimpande zigatsha khona ekuphenduleni ukutholakala kwamanzi emhlabathini.
I-Hydrosignalling yindlela izitshalo ezizizwa ngayo ukuthi amanzi akuphi, hhayi ngokukala amazinga omswakama ngokuqondile kodwa ngokuzwa amanye ama-molecule ancibilikayo ahamba namanzi ngaphakathi kwezitshalo. Lokhu kungenzeka kuphela ngoba (ngokungafani amaseli ezilwane) amaseli ezitshalo axhumene namanye ngama-pores amancane.
Lezi zimbotshana zivumela amanzi kanye nama-molecule amancane ancibilikayo (kuhlanganise namahomoni) ukuthi ahambe ndawonye izimpande amaseli nezicubu. Lapho amanzi ethathwa yimpande yesitshalo, ahamba phakathi kwamangqamuzana e-epidermal angaphandle.
Amaseli ezimpande angaphandle nawo aqukethe a i-hormone ekhuthaza i-branching ebizwa ngokuthi i-auxin. Ukuthatha amanzi kubangela ukuhlangana ngokuhlanganisa i-auxin ngaphakathi kwezicubu zezimpande zangaphakathi. Uma amanzi engasatholakali ngaphandle, yithi lapho impande ikhula ngesikhala esigcwele umoya, ichopho lempande lisadinga amanzi ukuze likhule.
Ngakho lapho izimpande zingakwazi ukumunca amanzi enhlabathini kufanele zithembele emanzini aphuma emithanjeni yazo ekujuleni kwempande. Lokhu kushintsha isiqondiso sokuhamba kwamanzi, okwenza manje ahambe ngaphandle, okuphazamisa ukugeleza kwe-hormone ye-branching auxin.
Isitshalo siphinde senza i I-anti-branching hormone ebizwa ngokuthi i-ABA emithanjeni yezimpande zayo. I-ABA ihamba nokugeleza kwamanzi nayo, iye kolunye uhlangothi kuya ku-auxin. Ngakho-ke lapho izimpande zidonsa emanzini avela emithanjeni yezitshalo, izimpande nazo zidonsa i-hormone ephikisana namagatsha kuzo.
I-ABA imisa ukuhlanganisa izimpande ngokuvala zonke izimbotshana ezincane ezixhuma amaseli ezimpande—okufana nokuqhuma kweminyango yomkhumbi. Lokhu kuvala amangqamuzana ezimpande komunye nomunye futhi kumise i-auxin ukuhamba ngokukhululeka emanzini, kuvimbe ukuhlukana kwezimpande. Lolu hlelo olulula luvumela izimpande zezitshalo ukuthi ziguqule kahle isimo sazo esimweni samanzi sendawo. Kunjalo ebizwa ngokuthi i-xerobranching (kubizwa ngokuthi zerobranching).
Ucwaningo lwethu luphinde lwathola ukuthi izimpande zesitshalo zisebenzisa uhlelo olufanayo ukunciphisa ukulahleka kwamanzi njengamahlumela aso. Amaqabunga ayeka ukulahlekelwa kwamanzi ngesikhathi sezimo zesomiso ngokuvala izimbotshana ezincane ezibizwa nge-stomata ezindaweni zazo. Ukuvalwa kwe-Stomata nakho kubangelwa ihomoni ye-ABA. Ngokufanayo, ezimpandeni ABA kunciphisa ukulahlekelwa kwamanzi ngokuvala ama-nano-pores abizwa nge-plasmodesmata axhumanisa wonke amangqamuzana ezimpande.
Izimpande ezivela kutamatisi, i-thale cress, ummbila, ukolweni kanye nebhali konke kusabela emswakama ngale ndlela, naphezu kokushintshashintsha kwenhlabathi nezimo zezulu ezahlukene. Ngokwesibonelo, utamatisi udabuka ogwadule lwaseNingizimu Melika, ngenkathi thale cress ivela ezindaweni ezipholile zase-Asia. Lokhu kuphakamisa ukuthi i-xerobranching iyisici esivamile ezitshalweni eziqhakazayo, ezingaphansi kweminyaka eyizigidi ezingu-200 kunezitshalo ezingaqhakazi ezifana nama-ferns.
Izimpande ezivela kuma-ferns, uhlobo lwezitshalo zasezweni ezikhula ngokushesha, aziphenduli emanzini ngale ndlela. Izimpande zabo zikhula ngokufana. Lokhu kuphakamisa ukuthi izinhlobo zezimbali zingcono ukuzivumelanisa nazo amanzi ukucindezeleka kunezitshalo zangaphambili zomhlaba ezifana nama-ferns.
Izitshalo eziqhakazayo zingahlanganisa izinhlobonhlobo zemvelo nezindawo kunezinhlobo ezingaqhakazi. Uma kubhekwa izinguquko ezisheshayo zamaphethini emvula emhlabeni wonke, ikhono loku izitshalo ukuzwa nokuzivumelanisa nezimo ezihlukahlukene zokuswakama kwenhlabathi kubaluleke kakhulu manje kunangaphambili.