Fiziološki aspekti otpornosti hrasta lužnjaka (Quercus robur L.), cera (Quercus cerris L.) i crne topole (Populus nigra L.) u uslovima vodnog deficita

Abstract

U radu je ispitan uticaj vodnog deficita na fiziološke osobine klonova crne topole i populacija hrasta lužnjaka i cera, kao i mogućnost oporavka ovih biljaka nakon ponovnog uspostavljanja optimalnog vodnog režima. Cilj istraživanja je bio da se ukaže na potencijal ispitivanih genotipova topole i hrastova za opstanak u promenljivim uslovima životne sredine, u skladu sa aktuelnim klimatskim promenama koje uključuju smanjenje količine padavina i ograničenu dostupnost vode. Dobijeni rezultati su pokazali specifično variranje ispitivanih morfo-anatomskih, fizioloških i biohemijskih parametara koje je zavisilo od momentalne vlažnosti zemljišta na primenjenom tretmanu (kontrola, suša praćena oporavkom, konstantna suša) i od genotipa biljke. Negativan uticaj vodnog deficita na tretmanu konstantne suše je u najmanjoj meri bio ispoljen na rastenje klona topole X/32, populaciju hrasta lužnjaka L1 i populaciju hrasta cera C1. Indeks tolerancije na stres izračunat na osnovu visine biljke (PHSI) takodje je potvrdio dobru morfološku prilagodjenost pomenutih genotipova na uslove suše. Dobijene vrednosti indeksa stoma ukazuju da vodni status ispitivanih populacija hrastova nije bio naroĉito pogodjen vodnim deficitom na sušnim tretmanima. Tretman konstantne suše je u oba ogleda doveo do najvećeg smanjenja vrednosti parametara razmene gasova kod skoro svih genotipova. S druge strane, primenjeni sušni tretmani nisu uslovili smanjenje sadržaja fotosintetiĉkih pigmenata, kao ni parametra Fv/Fm, kod većine ispitivanih biljaka. U odnosu na kontrolu, sadržaj prolina u listovima ispitivanih biljaka na tretmanu konstantne suše bio je znaĉajno povećan, a aktivnost enzima nitrat-reduktaze značajno smanjena, kod većine genotipova. Genotipovi kod kojih u uslovima jakog vodnog deficita nije došlo do značajne promene većine ispitivanih morfo-anatomskih, fizioloških i biohemijskih parametara mogu biti od velike važnosti kad je u pitanju njihov odabir i upotreba za uspešno pošumljavanje sušnih staništa, kojih će biti sve više usled negativnog uticaja brojnih ekoloških činilaca nastalih kao posledica klimatskih promena.

The impact of water deficit and recovery on physiological features of the black poplar clones, as well as of the oaks populations were analyzed. The aim of this research was to indicate the potential of the studied genotypes for survival under changing environmental conditions, in accordance with current climate changes, which include the reduction in amount of rainfall and limited water availability. Obtained results have shown a specific variation of studied morpho-anatomical, physiological and biochemical parameters which depended on soil humidity on the applied treatment (control, drought followed by recovery and permanent drought), as well as on plant genotype. Water deficit on permanent drought treatment had little negative effect on plant growth of poplar clone X/32, as well as oak populations L1 and C1. Plant height stress tolerance index also confirmed good morphological adaptation to drought of these genotypes. Stomatal index was not negatively affected by water deficit in oak plants. In both experiments, a permanent drought treatment led to the largest reduction in the values of gas exchange parameters in almost all genotypes. On the other hand, concentration of photosynthetic pigments was not considerably decreased in plants exposed to water deficit, as well as the parameter Fv/Fm, in most examined plants. Compared to the control, the impact of permanent drought treatment on biochemical parameters was expected, in the most cases. Compared to the control, proline content in leaves of most examined genotypes was significantly increased on permanent drought treatment, while nitrate reductase activity was significantly decreased. Examined genotypes exhibiting slight or no reduction in values of the most examined parameters during severe drought stress, could be used for afforestation in arid sites. Arid habitats appeared to be more numerous due to the effects of global climate changes.