Effect of Container Type on Growth and Developtment of Seedlings of Common Cypress (Cupressus sempervirens var. pyramidalis Nyman) in Nurseriers and Forest Cultures

Rast i razvoj sadnica običnog čempresa (Cupressus sempervirens var. pyramidalis Nyman) koje su se uzgajale u različitim kontejnerimapratio se tijekom jedne godine uzgoja u rasadnicima u Omišu i u Šibeniku, te pet godina u šumskoj kulturi, posađenim na podrivanoj površini riperom i uiskopanim jamama 40 x 40 x 40 cm na pokusnoj plohi Podi kod Šibenika. Korištena su tri tipa kontejnera: Bosnaplast 12, Bosnaplast 18 i PVC tuljak 7/24, koji su napunjeni standardnom mješavinom treseta i zemlje u omjeru 2:1. Sjetva u kontejenerima je obavljena 23. travnja 2003. godine. Nakon nicanja biljaka obavljene su izmjere i analize jednogodišnjih biljaka u rasadnicima i u laboratoriju. Izmjere su obavljene sukcesivno svaka dva mjeseca u 3 navrata. Varijable koje su proučavane u rasadnicima i laboratoriju bile su: visina stabljike, promjer vrata korijena, težina korijena, ukupna dužina korijena, prosječni promjer korijena, težina stabljike, ukupna težina biljke, odnos težine stabljike i korijena. Na pokusnoj plohi Podi su svake godine u razdoblju od 2003. do 2008. godine, kod svih posađenih biljaka, izmjerene njihove visine i utvrđeni postotci preživljenja. Volumen kontejnera po zitivno je utjecao na morfologiju jednogodišnjih biljaka u rasadnicima i njihov bolji rast na plohi, pogotovo kod biljaka posađenih na podrivanom tlu riperom. Najveće i najkvalitetnije biljke u rasadnicima proizvedene su u PVC tuljcima, kontejnerima s volumenom od 923 cm3i s odnosom visine i promjera 3,4; zatim u kontejnerima Bosnaplast 18 volumena 220 cm3, te najmanje u kontejnerima Bosnaplast 12 volumena 120 cm3. Istraživanjima je utvrđeno da su biljke u kontejnerima s većim volumenom imale i bolji rast na terenu te veći postotak preživljenja.Cypress is a forest tree species that is widely distributed across the entire Mediterranean region. Grown in the Adriatic area, in many coastal and island localities of Central and South Dalmatia it regenerates naturally but does not form large forest stands. Instead, it occurs in smaller orbigger groups. It is mostly found near Orebić, Župa Dubrovačka and further south, while some individual trees can also occur in the warmer sub-Mediterranean parts of Obrovac, Knin, Vrlika and Sinj. Compared to many other Mediterranean species, cypress has a very large distribution range and should, therefore, have an important role in afforesting karst areas, particularly in view of its great economic, ecologic and landscape value. This paper investigates the impact of container type on the development of common cypress grown in nurseries and forest cultures at various methods of preparing the soil for afforestation. The research was undertaken in the nurseries of Split Forest Administration and in the experimental plot Podi in thearea of Šibenik Forest Office. The goal was to determine which of the studied containers, already in use in regular forest production for several years, have the greatest impact on the development of cypress seedlings in the nurseries and in the experimental plot. The seedlings were planted in the soil undermined with a ripper and in dug holes. Three types of containers were used: Bosnaplast 12, Bosnaplast 18 and PVC bag 7/24. The containers were filled with standard 2:1 peat and soil mixture commonly used in regular nursery production. The seeds were hand-sown in containers on 23 April 2003. After reaching one year, the plants were measured and analyzed in the nurseries and laboratories. The variables studied in the nurseries and laboratories included plant height, root collar diameter, plant weight, root weight, total plant weight and plant weight - root weight ratio. Root system deformations were observed in each container during plant measurements. Measurements were carried out successively every month on three occasions. Each time three plants were chosen (maximal, medium and minimal height) from each container for morphologic determination. Plant heights were measured with a ruler in cm and root collars with a shubler. The weight of the aboveground and underground plant part was measured with precise scales to two decimals. Scener STD 1600 and Vin RHizo Pro software were used to determine overall length of all the root parts by diameter degrees, as well as total volume, volume by diameter degrees, the average root diameter and root area. In the experimental plot of Podi, the block method was used to prepare the soil and plant the seedlings in the soil undermined with a ripper, and so was classical afforestation in the holes of 40 x 40 x 40 cm. A total of 826 plants were planted in three separate blocks of 40 x 50 m and monitored. After planting one-year-old seedlings of common cypress, the heights of all the planted stock were measured annually over the period 2003 to 2008 and the survival percentage was determined. A correlation-regression analysis was applied to determine the quantitative grades of particular variables (container type, planting method) on the growth and development of common cypress seedlings in the nurseries and in the experimental plot. Container volume had a strong and positive effect on the growth and development of one-year-old seedlings of common cypress in the nursery (Table 1). Plants grown in larger-volume containers (PVC 7/24) attained bigger heights (r2 = 0.981), bigger plant weight (r2 = 0.985) and bigger root weight (r2 = 0.792), compared to plants grown in smaller containers (B18), particularly in Bosnaplast 12 containers (Figure 1). Research showed that cypress seedlings developed differently not only in different but also in the same container type. The first analysis of the root system done four months after sowing showed very poor root growth of cypress seedlings, especially of less developed ones, in all container types (Figure 2). Only by the end of October and the beginning of November was root development satisfactory in better developed plants grown in Bosnaplast 12 containers, but not so in Bosnaplast 18 and PVC 7/24 containers. The root system developed better and was richer in a PVC bag than in a B18 container, and especially in a B12 container (Figure 4). During one vegetation, no spiraling of the root system was observed in plants grown in these containers, or it was very slight (Figures 3 and 5), whereas root development, particularly in poorly developed plants, was not adequate. For this reason, seedlings of common cypress should be kept in PVC 7/24 containers and in B18 containers for more than one vegetation, but not longer than for two vegetations. Table 2 shows data on average heights of common cypress plants and their survival percentages by container type and planting method in the first five years of research in the experimental plot. According to the Table, at the end of the first vegetation period, taking into account all container types and afforestation methods, the survival of common cypress plants ranged from 28.0 % to 78.8 %. The best results were obtained in the soil undermined with a ripper and planted with seedlings from PVC 7/24 containers (78.8 %), followed by plants from B18 containers (62.5 %), and plants from B12 containers (61.3 %). In the experimental plot the survival percentage of common cypress planted with a classical method in dug holes was by 50 % lower than that of plants planted in the ripped soil in all container types. Regression analysis showed the dependence of plant survival percentage and plant height in the plot on container type and planting method (Figures 7 and 8). Plants of common cypress growing in larger containers and undermined soil attained bigger heights (r2 = 0.981) and bigger survival percentage (r2 = 0,792) than those planted in holes. Five-year monitoring of plant development in the experimental plot showed that the afforestation method with common cypresses planted in the soil undermined with a ripper to 50 to 70 cm in depth gave better results than the classical method of afforestation in dug holes of 40 x 40 x 40 cm. Common cypress plants from polyethylene bags of 923 cm3 planted in the soil undermined with a ripper had an average height of 74.5 cm and maximal height of 181.0 cm. Those planted in dug holes reached a height of 54.5 cm and maximum height of 128.0 cm (Figures 9 and 10). Plants from B12 containers showed the smallest height increment. The average plant height in the soil undermined with a ripper was 48.4 cm and the maximal height was 101.0 cm, while that in dug holes was 38.4 cm to 76.0 cm. The above data show that common cypress is a very useful species for afforesting karst areas and establishing mixed cultures in particular, on condition that the soil is properly prepared for afforestation and only good quality planting stock used. This material includes two-year-old seedlings grown in larger volume containers (900 to 1000 cm3). Planting should be timely and expertly performed and obligatory tending treatments should be applied in the first several years after planting