Neshzani

Neshzani, neshzanni tukhm, rushdi tukhm, prosessi az holati oromi ba faoliyati purshiddati hayoti guzashtani tukhm, ki dar natijai on chunin sabzida, navnihol tashakkul meyobad; marhalai ibtidoii ontogenezi rastani meboshad. Neshzani faqat hangomi budani miqdori kofii nami, oksigen, harorati muayyani garmi va bazan rejimi muayyani rush­noy ba amal meoyad. Neshzani bo afzoishi mubodilai moddaho dar janin va en­dosperma tavsif meshavad. Hangomi ba tukhm rasidani ob on varam karda, fermenthoyash faol gashta, jarayoni taodili moddahoi zakhiravi (ohar, ravgan, safedaho) va asosan tajziyai onho ba qand, kislotahoi ravgan, aminokislotaho shiddat meyobad.

In boshad, tukhmro bo energiya va moddahoi plastiki tamin menamoyad. Badi varam kardani tukhm janini on nesh mezanad. Odatan, avval resha mesabzad, ki on pusti tukhmro surokh karda mebaroyad. Sipas dar baze rastaniho gipokotil (in dam tukhmpalla va sarmugcha ba rui khok meba­royad) va dar rastanihoi digar epikotil (tukhmpalla dar zeri khok memonad va ba rui khok faqat sarmuggcha mebaroyad) numu mekunad. Ehtiyoti tukhm ba ob hangomi Neshzani ba tarkibi khimiyavi va gayra holati fiziologii tukhm vobasta ast. Hangomi narasidani oksigen, masalan, muddati daroz dar ob nigoh doshtan yo safolak bastani khok dar tukhm spirti etil, kislotai shir, ammiak va digar moddahoi baroi janin zararnok hosil meshavand.

Tasiri harorat ba Neshzanii tukhm na tanho ba namii on va shiddatyobii mubodilai moddaho, balki ba tagyiri tanosubi tanzimkunandai rush­di rastaniho niz vobasta ast. Masalan, hangomi garm kardani chigit yo chormagzi zamini (arakhis), ki nav gundoshta shudaast, miqdori ingibitorhoi rushdi on kam va Neshzanii tukhm tez meshavad. Baroi tezonidani Neshzanii tukhmi bisyor rastanihoi digar, baraks, tasiri harorati pasti garmi (nig. Stratifikatsiyai tukhmi), ki dar natijai on miqdori gibberellinho va gayraho amgezai rushdi rastaniho meafzoyad, zarur ast.

Baroi Neshzanii tukhmi baze rastaniho gayr az na­mi, oksigen va harorati musoid, ravshanii spektri muayyan niz zarur ast. Masalan, nuri surkh Neshzanii tukhmi kohu, sanavbar, shilkharo meangezad, nuri infrasurkh boshad, baraks, onro bozmedorad. Hatto baroi Neshzanii tukhmi yak rastani, ki az yak khusha girifta shudaast, sharoithoi gunoguni muhit zarur ast. Tukhmi baze rastaniho bo vujudi dar sharoiti musoid budanashon namesabzand. Sababi nasabzidani tukhm in ast, ki onho yo az holati oromi nabaromadaand yo pusti sakhti onho oksigen va obro ba janin nameguzaronad.

Neshzanii tukhm barobari ba gizogirii avtotrofi guzashtani navnihol ba itmom merasad. Pas, muhayyo karda­ni sharoiti musoid baroi Neshzanii tukhm, yane behtar gardonidani qobiliyati sabzishi tukhmi yake az sharthoi ho­sili baland meboshad.