SOWING SCOTS PINE SEED WITH A MODIFIED SINGLE-SEED SEEDER UNDER CONTROLLED CONDITIONS

Józef Walczyk, Paweł Tylek

ABSTRACT

A tool carrier was designed for work in closed spaces. A sowing section of the seeder was modified, which permitted sowing of Scots pine seed in rows, 0.05 m wide. Modification of the sowing assembly also permitted to sow two rows during a single passage of the section, and this increased efficiency of sowing. Results of this study showed that the designed unit can be used for sowing under controlled conditions. Apart from better distribution of seedlings in comparison with hand sowing, a 35 % seed saving was obtained.

Key words: single-seed sowing, seed sorting..

INTRODUCTION

Up to the present, there are no machines in the forest nursery practice , especially in the case of sowing under covers, permitting to achieve a proper horizontal and vertical distribution of seeds. Hand sowing or sowing with primitive wheel-barrow drill-seeders, most frequently with a brush sowing assembly, are commonly used [1, 2, 3, 5]. Distribution of seeds during sowing should assure similar conditions of development for each seed. This means that area alloted to a single seed should be circular or rectangular in shape, and the substrate covering seeds should be of a constant depth. Such sowing assures a good access of air, water and nutrients [9]. These conditions are best fulfilled by single-seed sowing. To make sure that single-seed sowing fulfills agrotechnic requirements the seeding material should have a very high germinative capacity [7, 8]. However, single-seed seeders, appropriate for sowing of seed of forest trees, and at the same time suitable for work in small areas under c over, are not available in the market [4].

THE AIM AND OBJECT OF STUDY

To fill in a gap in technique of sowing seed of forest trees under controlled conditions it was decided to adapt a sowing section of existing seeders used for single-seed sowing, and to assess its usability for sowing under controlled conditions. To achieve this aim the following work was carried out:

1. Designing of a tool carrier with an electric drive suitable for installation of the seeder’s sowing section.

2. Modification of the sowing section of the Omega S079 seeder designed for sowing of sugar beet, which is produced by the ROLMASZ factory in Kutno.

3. Comparison of machine sowing in a greenhouse with hand sowing used hitherto.

PLACE AND RESEARCH CONDITIONS

Research was carried out in the forest nursery of the Olkusz Forest District. Sowing of Scots pine seeds, collected in a managed stand, was completed on 28 April 2004. Seed viability was 96 %, while seed weight 6.8 g/1000 seeds. Seeds were sown in rows, 0.05 m apart, and the distance between seeds in a row was 0.043 m. Therefore analytical there were 467 seeds/m². For comparison reasons also hand sowing, 5.8 g/m², was carried out, which gave 819 seeds/m², taking seed viability into account.

DESCRIPTION OF SEEDER’S DESIGN

A study included construction of a tool carrier, on which a modified sowing section of the seeder was installed. The unit was mainly designed for work in plastic tunnels and greenhouses, but it may also be used for sowing in troughs or in open area. Since space in greenhouses and plastic tunnels should be utilized to a maximum the row spacing should be small. Under these conditions, due to construction difficulties, it is impossible to apply as many sections as it would be required to sow the entire seedbed in a single passage. Therefore the sowing section had to be installed in such a way that it can be shifted on the seeder’ frame, and a repeated passage of the unit’s wheels along the same track was necessary. For this reason the guidance of the seeder was accomplished with help of a sectional track (fig. 1), which is a certain disadvantage of this method. In the case of application of such a system of sowing in plastic tunnels and greenhouses the guides can be placed in permanent brick passages [6, 9].

A tool carrier, designed during this study, is composed of a frame supported on 4 wheels, two drive wheels in the front, and two supporting wheels in the rear. The rear wheels are self-aligning to make the frame guidance on the track easier. An electric power transmission system is mounted on the right side of the frame (fig. 2). It drives the drive shaft of the wheels with help of a chain transmission. From this shaft the drive shaft of the seeder is propelled by a multistage chain gear. There is a beam in the front part of the frame, on which the seeder’s section slides. Under the beam there is a revolving power screw which cannot slide. It serves to a crosswise displacement of the section, and it is ended with a crank. A fan, driven by an electric motor, and being the source of vacuum for the seeder, is mounted in the rear part of the right side of the frame. A connection of the drive shaft of the seeder with the ground wheel with help of a multistage chain gear permi ts to subject the number of seeds sown to a distance covered. The change of the transmission ratio in the power transmission system (fig. 3) makes the choice of setting of the seed spacings in a row possible.

The motor together with the reducer has 54 revolutions per minute, and this, at a dynamic radius of the ground wheel of 0.14 m and the transmission ratio Z₂/Z₁ equal to 2, gives a driving speed of 0.4 m/s. A single-phase motor is able to change the direction of revolutions. It is conrolled using a control box held in hand by the operator. Thanks to such a disign the driving direction of the seeder can be easily changed. Under field conditions it is possible to supply power to the assembly by a 2kW generating set. This possibility was checked during investigations. The supply current is conveyed by an electric wire fastened to a tight rope.

MODIFICATION OF THE SEEDER’S SOWING SECTION

For sowing, a section of the pneumatic seeder was used, since this type of seeders is not sensitive to shape of seeds. After a certain adaptation it permits to sow seeds of different species of forest trees. The view of the section fastened to the seeder’s frame is shown in fig. 4.

The sowing section is movable and can be shifted on the seeder’s frame (fig. 2). This permits to set any width of rows. During a working movement of the seeder one row is being sown, then the section of the seeder is lifted up by a self-lift (fig. 5) and the seeder starts to return, while the sowing section is shifted on the frame for the distance equal to width of a row (one revolution of the crank shifts the section for 2.5 mm), then the section is lowered down and the next working motion takes place.

The sowing assembly of the seeder’s section was modified adjusting it to a two-row sowing. This modification included making of a sowing disk with two rows of holes, widening of the ring of the vacuum channel (fig. 5), installation of a baffleplate in a seed chamber in order to limit the amount of seed remaining in the chamber, and installation of a proper seed scraper (fig. 6c) to ensure that seeds from individual rows of holes in the disk are sown in rows which required making of a new two-row coulter. A view of replacement of the disk of the sowing section and modifications of the section made is shown in fig. 6.

a	b	c	d

Thanks to modification of the sowing section it is possible to sow two rows during a single passage of the seeder’s section, and this doubled the labour efficiency.

The adjustment of spacing of seeds in a row is possible by replacement of a sowing disk with a disk having a different number of holes, or by changing the transmission ratio in the power transmission system of the disk. The seed spacing in a row possible to attain for two disks of a different number of holes are given in Table 2.

To sow two rows durin a single passage of the seeder it was necessary to make a 2-row coulter. A view of the coulter is shown in fig. 7.

a

b

To press seeds to soil in furrows a pressure wheel with two rubber rings, spaced according to the width of rows, was made. The wheel is empty inside and has an opening on its side for filling the wheel with sand to increase its weight, thus increasing the pressure exerted on seeds. The pressure of the wheel can also be increased by putting a pressure regulation spring under tension (fig. 4). A view of the pressure wheel is shown in fig. 8.

a

b

RESULTS

Single-seed sowing, also in a greenhouse, resulted in obtaining a higher number of seedlings per square meter, and their better area distribution in comparison with hand sowing. The process of sowing is presented in the film.

The number of seedlings per square meter was calculated in all study plots on 22 October 2004. The results of this counting showed that in the greenhouse in the case of single-seed sowing this number was by 11 % higher than the analytical number of seeds sown (fig. 9). This indicated that in 11 % the disk holes contained two seeds. In the case of hand sowing in the greenhouse seedlings were obtained from only 52 % of seeds. This showed that during hand sowing seeds are unevenly distributed and unevenly covered. Their large portion does not have favourable conditions for germination.

The results of this study showed that single-seed sowing not only makes the mechanization of sowing possible, thus eliminating a heavy manual work, and results in a better area distribution of seeds (fig. 10), but also results in a considerable saving of seed material since the number of seedlings obtained was by about 35 % higher than in the caso of hand sowing.

a	b

It may also be supposed that seedlings obtained by single-seed sowing will be more homogeneous, and therefore of a better quality. A study on seedling quality will be conducted during their spring extraction.

CONCLUSIONS

1. A tool carrier, designed during this study, fulfilled requirements permitting to conduct sowing in a greenhouse, and to keep exact distances between rows.

2. Modification of a sowing section of the seeder permitted to sow Scots pine seeds simultaneously in two rows, 0.05 m apart.

3. The number of seedlings per square meter obtained, as well as area distribution of seeds, were better in the case of single-seed sowing in comparison with hand sowing.

4. Single-seed sowing provided better conditions for germination and growth, and permitted to save about 35 % of seeds in comparison with hand sowing.

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