Bruno NOVAK, Ivanka ŽUTIĆ, Nina TOTH

Agronomski fakultet Sveučilišta u Zagrebu, Zavod za povrćarstvo, Svetošimunska 25, Zagreb (E-mail: bnovak@agr.hr)

Uvod

Slatki krumpir ili batat (Ipomea batatas L.), višegodišnja tropska biljka iz porodice slakova (Convulvulaceae), ima veliku nutritivnu vrijednost i naglašena ljekovita svojstava. Za jelo se koriste sekundarna zadebljanja korijena (Rubatzky i Yamaguchi 1997), a pretežno se uzgaja na jednogodišnji način. Zadnjih se godina njegov uzgoj iz tropskih područja sve više širi i u druge dijelove svijeta. Obzirom da batat za rast i razvoj treba godišnje minimalno tri mjeseca s temperaturom zraka iznad 15 °C, to mu današnje doba globalnog zatopljenja povećava mogućnost uzgoja i u većem dijelu Europe (Novak et al. 1998). U Hrvatskoj je već provedeno trogodišnje preliminarno istraživanje mogućnosti njegovog uzgoja i introdukcije u naše uzgojno područje. U cilju postizanja što većih prinosa tijekom relativno kratke vegetacije ove kulture, a uz korištenje raspoloživih metoda sukladnih principima održivog uzgoja povrća, postavljen je pokus s endomikoriznim uzgojem batata uz malč različito obojenih polietilenskih (PE) filmova.

Materijal i metode

Istraživanje je provedeno na pokušalištu Zavoda za povrćarstvo Agronomskog fakulteta u Zagrebu. Dvofaktorijelni poljski pokus postavljen je po split-plot shemi u 4 ponavljanja, pri čemu glavni faktor endomikoriza ima dvije razine (inokulirane i neinokulirane biljke), a podfaktor malč obojenog PE-filma ima četiri razine (crni, smeđi i bijelo-crni film te neprekriveno tlo). Presadnice batata uzgojene su u plasteniku i sađene 16. svibnja na razmak 0,7 m x 0,5 m (2,85 biljaka/m2), po 12 biljaka na osnovnu parcelu. Za varijantu endomikorize presadnice su neposredno prije sadnje inokulirane otopinom spora endomikorizne gljive Glomus mossae (BEG 12). Pokus je proveden bez navodnjavanja, gnojidbe i zaštite od bolesti i štetnika. Ručna berba obavljena je 19. rujna, pri kojoj su promatrani parametri broj i masa zadebljalih korjenova po biljci, iz čega je preračunat prinos po jedinici površine te prosječna masa korijena.

Rezultati i diskusija

Inokulacijom biljaka batata endomikoriznom gljivom dobiveni su opravdano viši prinosi u odnosu na neinokulirane biljke (tablica 1), što potkrepljuje tvrdnju da je dobrom uspostavom mikorize moguće ostvariti bolje primanje hraniva iz tla, a time i povećanje prinosa. Ovime se dokazuje značaj mikorize u uzgoju povrća, posebice u održivoj i ekološkoj proizvodnji povrća (Hooker i Black 1995). Promatranjem visine prinosa s aspekta utjecaja obojenog PE-malča, dobiveni rezultati govore u prilog primjene crnog PE-filma (5.28 kg/m2). Obzirom da je batat kultura koja postiže veće prinose kod viših temperatura tla (18 do 24 °C), malčiranje tla crnim PE-filmom omogućava da se u kraće vrijeme, do zatvaranja sklopa, postignu povoljniji uvjeti za rast, čime se u konačnici dobiva i viši prinos (Hochmuth i Howell 1983). Najviši prinos (6.71 kg/m2) ostvaren je pod utjecajem interakcije mikorize i prekrivke crnog PE-filma.

Tablica 1. Prinos korjenova batata (kg/m²)

Inokulacija biljaka batata endomikoriznom gljivom nije značajno utjecala na broj zadebljalih korjenova/biljci (5.9 vs. 6.1, tablica 2). Na isto svojstvo također nije značajno utjecao malč obojenih PE-filmova, budući da su podjednaki prinosi ostvareni na prekrivenim, kao i na neprekrivenim parcelama (5.7 do 6.6 korjenova/biljci).

Tablica 2. Broj korjenova batata/biljci

Najveća prosječna masa korjenova batata je ostvarena kod inokuliranih biljaka i pod prekrivkom crnog PE-filma (tablica 3), čime se potvrđuje sposobnost boljeg primanja hraniva i vode iz tla kod mikoriziranih biljaka (Allen i Boosalis 1983), kao i lakše postizanje i održavanje povoljne mikroklime pod crnim PE malčem (Orzolek i Kamont 2002).

Tablica 3. Prosječna masa korijena batata (g)

Zaključak

Mikoriza ima signifikantni pozitivni utjecaj na prinos zadebljalih korjenova batata, kao i na prosječnu masu korijena, a ne utječe značajno na broj korjenova/biljci. Malčiranje tla različito obojenim PE-filmovima također značajno utječe na prinos i prosječnu masu korijena, pri čemu se najviši prinosi ostvaruju primjenom crnog filma, dok nema značajnog utjecaja na broj zadebljalih korjenova/biljci. Interakcija mikorize i malča crnog PE-filma osigurava opravdano najveći prinos.

Literatura

1. Allen M.F. i Boosalis M.G., (1983). Effects of two species of VA mycorrhizal fungi on drough tolerance of winter wheat . New Phytologist 93: 67-76.

2. Hochmuth G.J. i Howell I.C., (1983). Effect of black plastic mulch and raised beds on sweet potato growth and root yield in northern region. HortScience 18 (4): 615-620

3. Hooker J.E. i Black K.E., (1995). AM fungi as components of sustainble soil-plant system. Critical Rewievs in Biology 15 (3-4): 201-212

4. Novak B., Borošić J., Lešić R. Toth N. i Ban D., (1998). Mogućnost uzgoja nekih suptropskih kultura u Hrvatskoj. Zbornik radova "Prilagodba poljoprivrede i šumarstva klimi i njenim promjenama", HAZU, Zagreb: 201-208

5. Orzolek M.D. i Lamont W.J., (2002). Summary and recomendations for use of Mulch Color in Vegetable production, 30th National Agricultural plastic Congress-San Diego, CA

6. Rubatzky V.E. i Yamaguchi M., (1996). World vegetables. Chapman & Hall, New York

Bruno NOVAK, Ivanka ŽUTIĆ, Nina TOTH

University of Zagreb - Faculty of Agriculture, Vegetable Crops Department, Svetošimunska 25, Zagreb (E-mail: bnovak@agr.hr)

Introduction

Sweet potato, or batata (Ipomea batatas L.), is a perennial tropical plant of the Bindweed family (Convulvulaceae) with a great nutritional and health value. Its enlarged storage roots are used for food (Rubatzky and Yamaguchi 1997), and it is generally grown annually. Recently its cultivation has been showing increased spreading from its native tropical areas to other reagions of the world. Since the batata needs a yearly minimum of three months with air temperatures above 15 °C for its growth and development, current global warming increases its cultivation potentials in most parts of Europe (Novak et al. 1998). In Croatia a three year preliminary research has already been conducted to investigate the possibilities of its cultivation and introduction into our growing areas. For the purpose of achieving the highest possible yield during a relatively short vegetation period of this crop, and by applying available methods consistent with the principles of sustainable vegetable production, a trial with endo mycorrhizal cultivation of the batata with mulch of differently coloured polyethylene (PE) films has been set up.

Material and Methods

The research was conducted on a trial plot of the Vegetable Crops Department in Zagreb. A two factorial field trial was conducted in split-plot design with 4 replications, with the main factor, endo mycorrhiza, having two levels (inoculated and uninoculated plants), and the subfactor, mulch of coloured PE film, having four levels (black, brown, black/white and uncovered soil). The batata transplants were cultivated in a protected, heated space and planted on 16 May spaced at 0,7 m x 0,5 m (2,85 plants/m2), 12 plans per base plot. For the endo mycorrhiza variation transplants were inoculated, immediately prior to planting, by a solution of spores of endo mycorrhizal fungus Glomus mossae (BEG 12). The trial was conducted without irrigation, fertilization or protection from diseases or parasites. Hand harvesting was performed on 19 Sptember, accompanied by observation of parameters such as the number and mass of enlarged storage roots per plant, which then served as a basis for the calculation of yield per unit area and average root mass.

Results and Discussion

By inoculation of the batata plants with endo mycorrhizal fungus justifiable higer yields were achieved in comparison with the uninoculated plants (Table 1), which supports the hypothesis that by well established mycorrhiza it is possible to improve the absorbtion of nutrients from the soil, which in turn results in increased yield, and thereby proves the importance of mycorrhiza in vegetable production, particularly in sustainable, ecological vegetable production (Hooker and Black 1995).

Table 1. Batata root yield (kg/m²)

Based on the observation of the yield from the aspect of the influence of coloured PE mulch, the achieved results support the application of black PE film (5.28 kg/m2). Considering the fact that the batata achieves higher yields at higher soil temperatures (18 to 24 °C), mulching the soil with black PE film facilitates quicker creation of more favourable growth conditions, which eventually results in higher yields (Hochmuth and Howell 1983). The highest yield (6.71 kg/m2) was achieved with the influence of interaction of mycorrhiza and the black PE film cover.

The inoculation of the batata plants with endo mycorrhizal fungus had no significant effect on the number of enlarged storage roots per plant (5.9 vs. 6.1). The same characteristic was not significantly affected by the mulch of coloured PE-films, since approximately equal yields were achieved on covered and uncovered plots (5.7 to 6.6 roots/plant).

The highest average mass of the batata roots was achieved with inoculated plants and under black PE-film (Table 2), which confirms the ability of mycorrhized plants to better absorb nutrients and water from the soil (Allen and Boosalis 1983), as well as easier achievement and maintainance of favourable microclimate under black PE mulch (Orzolek and Kamont 2002).

Table 2. Average mass of batata root (g)

Conclusions

Mycorrhiza has a significant positive influence on the yield of the enlarged storage batata roots and on the average root mass; it, however, does not significantly influence the number of roots per plant. The mulching of soil with differently coloured PE-films also has significant influence on the yield and average root mass, with highest yields achieved by application of black PE film; this, however, does not significantly influence the number of the enlarged storage roots per plant. The interaction of mycorrhiza and the mulch of black PE film ensures justifiably highest yield.

References

1. Allen M.F. i Boosalis M.G., (1983). Effects of two species of VA mycorrhizal fungi on drough tolerance of winter wheat . New Phytologist 93: 67-76.

2. Hochmuth G.J. i Howell I.C., (1983). Effect of black plastic mulch and raised beds on sweet potato growth and root yield in northern region. HortScience 18 (4): 615-620

3. Hooker J.E. i Black K.E., (1995). AM fungi as components of sustainble soil-plant system. Critical Rewievs in Biology 15 (3-4): 201-212

4. Novak B., Borošić J., Lešić R. Toth N. i Ban D., (1998). Mogućnost uzgoja nekih suptropskih kultura u Hrvatskoj. Zbornik radova "Prilagodba poljoprivrede i šumarstva klimi i njenim promjenama", HAZU, Zagreb: 201-208

5. Orzolek M.D. i Lamont W.J., (2002). Summary and recomendations for use of Mulch Color in Vegetable production, 30th National Agricultural plastic Congress-San Diego, CA

6. Rubatzky V.E. i Yamaguchi M., (1996). World vegetables. Chapman & Hall, New York