Epsilon Archive for Student Projects

Abstract

Föryngring av skog är en nödvändig, men kostsam åtgärd och därför är det eftersträvansvärt att hitta en föryngringsmetod som är både kostnadseffektiv och ger en bra föryngring. Ett sätt att få en billigare föryngringsåtgärd är att använda frösådd. Vid en lyckad sådd gör det stora plantuppslaget att plantorna får bra förutsättningar för god kvalitet. Dessa plantor får dessutom bättre rotutveckling och stabilitet än planterade plantor. Användningen av skogssådd är dock begränsad av bl.a. frötillgången, ståndortens egenskaper och den korta såddsäsongen. Därför är det viktigt att försöka hitta sätt att förlänga såddsäsongen och minska fröåtgången samt ståndortegenskapernas inverkan på groningen. Den mest begränsande faktorn vid frögroning är vatten och det är därför viktigt att fröna har god tillgång till vatten när groningen påbörjas och fröna inte torkar ut. Även gasutbytet är viktigt vid frögroning.

Syftet med studien var att ta fram ett inledande kunskapsunderlag för ett föryngrings-system baserat på sådd av "fröpaket med vattenryggsäck", sådd av frön som börjar gro omedelbart efter såddtillfället tack vare bifogat vatten. Följande hypotes testades: Om man skickar med det vatten som behövs för groning i rätt förpackning går groningen mycket snabbt och det blir hög plantbildning även om den yttre miljön inte ger optimala fuktighetsbetingelser. Fyra försök utfördes med olika behandlingar. Alla försök genomfördes inomhus utan någon yttre tillförsel av vatten och fröpaketen var placerade på ett bord. Ljuskällan var endast rumsbelysning och ljus från ett fönster. I försöken studerades inverkan av olika substrat (H20 + torv + polymer och H20 + torv) och substratvolym, vattenhalt, olika förpackningssätt (plastfilm och plaströr med lock) samt olika nivåer av gasutbyte (0, 2, eller 10 hål i plastfilmen alternativt locket). I de två första försöken ingick polymeren Ac-Di-Sol® i samtliga behandlingar. Däremot i de två sista försöken innehöll hälften av proverna polymer och hälften var utan. I de tre första försöken användes plantagefrö från Skaholma medan i det fjärde försöket användes beståndsfrö från Karesuando varav hälften var vitaliserat och hälften fungerade som kontroll.

Substrat med polymer var signifikant (Fisher Exact ≤ 0.05) sämre än substrat utan polymer när det gäller groddplantbildning. De prover där substratet bestod av torv, vatten och polymer utvecklade inga groddplantor. Polymeren verkade ha haft en hämmande effekt på frögroning och groddplantbildning. Däremot i de prover som endast innehöll torv och vatten blev det stor andel groddplantor. Proverna i försök 3 med substratstorleken 4,2 cm3, vattenhalten 80.2 % och gasutbytet "10 hål" i plastlocket resulterade i 100 % groddplantor oberoende av rörstorlek. Groddplantor kunde bildas utan hål i plastlocket, men det blev bättre resultat med hål, dvs. ökat gasutbyte. De vitaliserade fröna resulterade i fler groddplantor och snabbare utveckling jämfört med kontrollfröna, vilket stämmer överens med tidigare forskning. Substratvolymen 4.2 cm3 verkar inte ha varit för liten för att frön ska kunna gro och etablera groddplantor, vilket borde kunna betyda att man kan använda sig av relativt små fröpaket vid sådd i skogen.
Studien visar att det går att få frön att gro genom att skicka med vatten även om den yttre miljön inte skulle tillåta adekvat vattenförsörjning enligt uppställd hypotes. Försöken med fröpaket visar att om metoden finslipas bör den kunna appliceras i fält för att förbättra frösåddtekniken.

Abstract (eng)

Regeneration of forests is a necessary but expensive measure. Therefore it is important to find a regeneration method that is both cost effective and that gives a good regeneration. There are several ways to regenerate forests and one way to get a less expensive regeneration is to sow. At a successful direct seeding there are a great number of seedlings which contributes to good conditions for high quality. These seedlings also get better root development and stability than planted seedlings. The utilization of direct seeding is limited by seed access, site properties and the short seeding season. Therefore it is important to try to find ways to prolong the seeding season and to reduce the seed consumption and also reduce the impact of the site properties on seedling emergence. The most limiting factor when it comes to germination is water. Therefore it is important that the seeds have access to water when the germination starts. It is also important that the seeds do not get dry. The gas exchange is also of importance for germination.

The purpose with this study was to put together a preliminary basis of knowledge for a system of regeneration based on seeding of "seed package with a water backpack", seeding of seeds that starts to germinate directly after the seeding thanks to attached water. The following hypothesis was tested: If you send the water required for germination in the right packaging the germination will be fast and the seedling establishment high even if the external environment does not give optimal moister conditions. Four experiments were done with different treatments. The experiments were conducted indoors without any external supply of water. The seed packages were placed on a table. The effect of different substrates (H20 + peat + polymer and H20 + peat), substrate volumes, water volumes, different packaging (plastic film or plastic tubes with a lid) and different levels of gas exchange (0, 2, or 10 holes in the plastic film or in the lid) was studied. The first two experiments included the polymer Ac-Di-Sol® in all treatments. The last two experiments were divided in two where half the samples included polymer and the other half did not. The first three experiments used plantation seeds from Skaholma while the fourth experiment used stand seed from Karesuando of which half was invigorated and half worked as a control.

Substrates with polymer were significantly (Fisher Exact ≤ 0.05) different from substrates without polymer when it concerns seedling establishment. No seedlings where established in the samples containing peat, water and polymer. The polymer seemed to have an inhibiting effect on germination and seedling establishment. However in the samples that only contained peat and water there was a big proportion of seedlings. The samples in experiment 3 with the substrate size 4.2 cm3, water content 80.2 % and gas exchange "10 holes" in the plastic lid resulted in 100 % seedlings independent of tub size. Seedlings were able to grow without any hole in the plastic lid, though the results were better when there were holes in the lid, due to increased gas exchange. The invigorated seeds resulted in more seedlings and better development compared to the control seeds, which agrees with previous research. The substrate volume 4.2 cm3 did not seem to have been too small for the seeds to establish germination and seedling establishment, which ought to mean that you can use relatively small seed packages for direct seeding. The study shows, according to the hypothesis, that you can get seeds to grow if you are able to send water with the seeds even if the external environment does not allow suitable water support. The experiments with seed packages show that if the method is polished it should be able to apply in the field to improve the technique of direct seeding.

Regeneration of forests is a necessary but expensive measure. Therefore it is important to find a regeneration method that is both cost effective and that gives a good regeneration. There are several ways to regenerate forests and one way to get a less expensive regeneration is to sow. At a successful direct seeding there are a great number of seedlings which contributes to good conditions for high quality. These seedlings also get better root development and stability than planted seedlings. The utilization of direct seeding is limited by seed access, site properties and the short seeding season. Therefore it is important to try to find ways to prolong the seeding season and to reduce the seed consumption and also reduce the impact of the site properties on seedling emergence. The most limiting factor when it comes to germination is water. Therefore it is important that the seeds have access to water when the germination starts. It is also important that the seeds do not get dry. The gas exchange is also of importance for germination. The purpose with this study was to put together a preliminary basis of knowledge for a system of regeneration based on seeding of “seed package with a water backpack”, seeding of seeds that starts to germinate directly after the seeding thanks to attached water. The following hypothesis was tested: If you send the water required for germination in the right packaging the germination will be fast and the seedling establishment high even if the external environment does not give optimal moister conditions. Four experiments were done with different treatments. The experiments were conducted indoors without any external supply of water. The seed packages were placed on a table. The effect of different substrates (H20 + peat + polymer and H20 + peat), substrate volumes, water volumes, different packaging (plastic film or plastic tubes with a lid) and different levels of gas exchange (0, 2, or 10 holes in the plastic film or in the lid) was studied. The first two experiments included the polymer Ac-Di-Sol® in all treatments. The last two experiments were divided in two where half the samples included polymer and the other half did not. The first three experiments used plantation seeds from Skaholma while the fourth experiment used stand seed from Karesuando of which half was invigorated and half worked as a control. Substrates with polymer were significantly (Fisher Exact ≤ 0.05) different from substrates without polymer when it concerns seedling establishment. No seedlings where established in the samples containing peat, water and polymer. The polymer seemed to have an inhibiting effect on germination and seedling establishment. However in the samples that only contained peat and water there was a big proportion of seedlings. The samples in experiment 3 with the substrate size 4.2 cm3, water content 80.2 % and gas exchange ”10 holes” in the plastic lid resulted in 100 % seedlings independent of tub size. Seedlings were able to grow without any hole in the plastic lid, though the results were better when there were holes in the lid, due to increased gas exchange. The invigorated seeds resulted in more seedlings and better development compared to the control seeds, which agrees with previous research. The substrate volume 4.2 cm3 did not seem to have been too small for the seeds to establish germination and seedling establishment, which ought to mean that you can use relatively small seed packages for direct seeding. The study shows, according to the hypothesis, that you can get seeds to grow if you are able to send water with the seeds even if the external environment does not allow suitable water support. The experiments with seed packages show that if the method is polished it should be able to apply in the field to improve the technique of direct seeding.