Swo Hisisa Naku Horisa Swibyariwa

©Louise Brodie

Ximilani xilava nkarhi wo hisa xikan’we na wotitimela eka swin’wana swakukula ka xona. Minkarhi leyi yo hisa nayo titimelayikombetiwa eka ti heat units nati chill units.

Swo Hisisa Dwibyariwa

Crop heat units (CHU) tikombisa nhlohletelo wa mahiselo eka makulelo ya swimilani. Kukula ka ximilani swiya hi nhlayo ya kuhisa loku ximilani xi hlanganaka nakona eka vutomi bya xona, leswi vuriwaka masiku yati degree. Mahiselo yale hansi ya hunguta kukula naswona mahiselo yo kufumela ya hatlisisa kukula.
E Afrika Dzonga, hi tirhisa 10°C, leyinga lulamela mavele, swibyariwa swahina swa ntolovelo, tani hi mahiselo yale hansi. Mahiselo lawa yale hansi i mahiselo lawa ximilani xi vavisekaka loko xiri eka wona, axi koti kukula kumbe xinga humelerisi nchumu. Mahiselo lawa yale hansi ya hambana kuya hi swimilani swohambana hambana. Xikombiso, mahiselo yale hansi i 4°C eka ti peas, ximilani xa mahiselo yo hola, 10°C ya mavele, ximilani xa tindzoho xa ximumu, 13°C eka malamula na mimova kutani 18ºC yati date palms.
Swin’wana swikatsa nhlohletelo wakukula ka swimilani; photoperiod (ku leha ka siku), ku nona ka misava xikan’we na mati emisaveni. Kuvupfa swinga hlwerisiwa (hiku tata mati) kumbe ku hatlisisiwa hikuva mati yari ehansi emisaveni.

Switsotswani na Mahiselo ya Swimilani

©Olaf Leillinger

Switsotswani swa swimilani naswona swihlohleteriwa hiku hisa naswona swina mahiselo yokarhi lawa yanga swiringanela. Leswi vulaka leswaku heat unit/degree-day yinga tirhisiwa ku tiva kuvonakala ka switsotswani leswi naswona kunguhata nongonoko wo fafazela murhi wa switsotswana.
Xikombiso, mahiselo yale hansi ya codling moth, xitsotswana xa milamula, mapecisi, nectarine apula naswin’wana, i 11ºC. Mahiselo yale hansi ya cotton bollworm i 14ºC, switsotswana swa swimilani swofana nati peas, beans, wheat, cotton, mavele, malamula, cucurbits, mazambala, matamatisi na lucerne. Loko ya oriental fruit moth, xitsotswana lexikulu swinene eka mapecisi, kuri ntsena 7ºC.

Xana Iyini ti Swotitimeta Swibyariwa?

©Louise Brodie

hill units titala kuvuriwa ‘positive chill units’ (PCUs). PCUs i marito fularha ya heat units. Kuhlayeleriwa lokunga twisisekeki loku endliwaka kuhlayela ti awara leti nyikiwaka mahiselo xikombiso 4°C. E USA, mahiselo ya 4.4°C na 7.2°C ya tirhisiwa tani hi mahiselo yale hansi kutiva ti awara to titimela.

Swibyariwa swilava mahiselo yale hansi hi swikongomelo swohambana. Swibyariwa swa mihandzu leswaku swita nghena eka nkarhi wowisa emakumu ka ximumu. Kukula kufika laha kuyimaka eka ximilani kufikela xitwa nhlayo yokarhi yo titimela hi xixika. Xikombiso, mapecisi ya lava mahiselo lawa yanga exikarhi ka 2.5°C na 9°C leswaku ya hetiseka.
Loko kuriku swilaveko swale hansi swa kutitimela aswi fikeleriwangi, swita vanga swiphiqo hi ximun’wana, kufana naku hlwela kakuva ku tshoveriwa (peaches - later harvest etc.) kumbe swinga fambi kahle eka mabilomu ya ma apula (apples - smaller, fewer fruit etc.). Leswi swihunguta swinene mbuyelo hinkarhi wa ntshovelo.
Eka swibyariwa leswi fanaka na mapecisi na ma apula, ti khemikali minkarhi yin’wana ta tirhisiwa ku pfuneta leswaku loko PCUs tinga ringanelanga kuva ntumbuluko wu humelela hi woxe eka nsinya, swipfuneta.
Eka kuhumelerisiwa ka mihandzu leyi kuna ku hleketelela leswaku ti PCUs tinga tirhisiwa ku vhumba leswaku kuyima kuhuma mabilomu xikan’we na masiku yantshovelo swingava kona rini. Swinga tlhela switirhisiwa ku hlwerisa kuhuma mabilomu, leswaku swita sivela ku onhiwa hi gwitsi, kumbe kutiva loko ndzhawu yoleyo yi lulamerile ku byala swibyariwa swokarhi.

Wheat yi lava ku titimetiwa, loku vuriwaka vernalization. Vernalization hi loko mahiselo yale hansi ya laveka ku pfuneta kuhuma mabilomu naku endliwa ka tindzoho.

©WRC

Translated by Ike Ngobeni