Strategies for improving tolerance for salinity in vegetables

Za uspešno gojenje in velik pridelek je potrebno zadostno gnojenje in namakanje, kar v tleh lahko povzroči prekomerno kopičenje soli, ki negativno vplivajo na rast in razvoj rastlin. V aridnih in semiaridnih območjih slana tla nastanejo zaradi močne evapotranspiracije in nezadostne količine padavin. Pomanjkanje pitne vode stopnjuje problem slanih tal, saj so kmetje prisiljeni v namakanje z vodo, katera ima visoko koncentracijo NaCl in drugih soli. Gnojenje in namakanje je problematično tudi pri gojenju v rastlinjakih, saj v zaprtih prostorih ne prihaja do naravnega spiranja soli v nižje plasti tal in je zato zasoljevanje še hitrejše. Vsaka vrtnina ima slanostni prag, ki določa mejo koncentracije soli, nad katero pride do težav pri rasti in razvoju rastline. Sol dobro prenašajo bučke, grah, kumare, brokoli in paradižnik, slabo pa korenje, jajčevec, čebula in solata. Posledice gojenja rastlin na slanih tleh so: oviran sprejem vode pri semenih, zaradi višjega osmotskega potenciala rastni substrati povzročajo toksičnost, ki spreminja aktivnosti encimov presnove nukleinske kisline, spremeni presnovo beljakovin, moti hormonsko ravnovesje in zmanjšuje izkoriščenost zalog semena. Povečana absorbcija soli povzroči kopičenje Na+ in Cl- v rastlini, ki povzročita hitrejše staranje in odpadanje listov, slabše delovanje fotosinteze, slabšo rast korenin itd. Da bi oblažili oz. se izognili posledicam soli, so se začele uporabljati različne strategije: križanje rastlin, razsoljevanje tal in danes najbolj učinkovito cepljenje rastlin na tolerantne podlage. Z omenjenimi strategijami povečamo in izboljšamo pridelek na slanih tleh.Successful cultivation and high yields requires a lot of fertilization and irrigation, which in the soil causes excessive accumulation of salt that negatively affects the growth and development of plants. In arid and semi-arid areas, soil salinity is formed due to strong evapotranspiration and insufficient rainfall. The lack of drinking water is compounding the problem of saline soils, as farmers are forced into irrigation with water, which has a high concentration of NaCl and other salts. Fertilization and irrigation is also problematic in the cultivation of greenhouses, because in the enclosed areas there is no natural washing of salt in the lower layers of soil, and therefore the salinization is even faster. Each vegetable has a saline threshold, which determines the salt concentration limit above which there is a problem with the growth and development of the plant. Salt is well tolerated by pumpkins, peas, cucumbers, broccoli and tomatoes, but poorly carrots, eggplant, onion and salad. The consequences of cultivating plants on saline soils are: impeded water acceptance in seeds, because of higher osmotic potential, growth media cause toxicity that changes the activity of enzymes of nucleic acid metabolism, changes protein metabolism, disturbs the hormonal balance and reduces the utilization of seed stock. Increased salt absorption results in the accumulation of Na+ and Cl- in the plant, which results in faster aging and leaf fall, poor photosynthesis, poor root growth, etc. To avoid the effects of salt, different strategies began to be used: crossbreeding plants, desalination of the soil and today the most effective grafting plants to tolerant rootstocks. With these strategies we increase and improve crop on saline soils