EFFECT OF NURSERY MATERIAL QUALITY AND MULCH TYPE ON THE GROWTH OF 3-YEAR OLD ‘FANTASIA’ NECTARINE TREES

Bożena Radajewska, Michał Szklarz
Department of Pomology, University of Agriculture in Poznan, Poland

ABSTRACT

One-year old trees of ‘Fantasia’ nectarine on the rootstock of Manchurian peach-tree were planted in 2004 in Przybroda near Poznań in the spacing of 4 × 2.5 m. The trees differed by their thickness (11-13 and >13-15 mm). Tree rows were mulched by fibre sheets or by mown grass. Equal irrigation and fertilization as well as other cultivation treatments were applied. Growth was estimated every year and in the third year, tree health was evaluated. Studies have shown that different thickness of planted trees had no significant effect on their growth in the first years in the orchard. Both the TCSA increments taking place every year and the height and projection of crown did not differ. The applied mulches protected well the soil against weeds. Herbicides were applied in tree rows next to mowed grass mulch. The type of mulch differentiated tree growth. Trees mulched with fibre sheets grew better than those mulched with mown grass; TCSA increments were greater, tree crowns were higher and they had a greater projection. Differentiated mulching did not have any significant effect on tree health, infection by Taphrina deformans and on symptoms of bark and wood diseases.

Key words: nectarine, tree quality, mulching, growth, health.

INTRODUCTION

Quality of nursery material is one of the basic factors affecting tree growth and earliness of yield after plantation [1, 12]. However, this effect quickly disappears after tree plantation in very good soil and climatic conditions [9]. Equally important is the soil cultivation system in orchard. It is known that the traditional fruit production methods requiring the use of great amounts of chemical agents have already been accepted by the consumers preferring not only the health values of products, but also the protection of soil environment. Therefore, since many years, production methods eliminating herbicide application have been searched for. This objective can be achieved among others by the use of different mulch types, both organic and synthetic ones. Synthetic mulches such as plastic foil or fibre sheets provide a physical barrier for weeds, they limit evapotranspiration and preserve water content in soil [3, 6]. Soil under synthetic mulching is more intensively heated [11]. Walsh et al. [13] reported that the increase of soil temperature under synthetic mulch can contribute to humus mineralization and increase the availability of mineral components. Organic mulches like straw, sawdust, mown grass or other organic waste material [4, 5] not only protect against weeds but they also can be an additional source of organic substances in the orchard [8], however, it is not known from which year after mulching they become available to the plants. Changes in some soil conditions under organic mulch and around the trees can also have some negative results. Erwin and Stiles [2] reported that maintained higher moisture with organic mulches can promote the spreading of some fungal diseases.

The objective of the present studies was the estimation of the growth and health of young nectarine trees with different thickness mulched with fibre sheets or mowed grass.

MATERIAL AND METHODS

The experiment was established in spring 2004 on grey brown podzolic soil on the area of Agricultural and Pomicultural Farm in Przybroda near Poznań. After the transportation from nursery, trees of ‘Fantasia’ nectarine on Manchurian peach-tree rootstock were segregated according to root neck thickness into 2 groups: 11<13 mm diameter and >13-15 mm diameter. Trees were planted in 4.0 × 2.5 m spacing, treatments consisted of 20 trees in random block design, and every tree was a replication. Two rows of trees were mulched with fibre sheets of 94 G.S.M. (grammes per square metre) and there didn’t use herbicides. Fibre sheets were spread in a belt of 1.5 m width. Trees in the remaining 2 rows were mulched with mown grass in interrows, where herbicides were used.

In the first year, in the interrows, mechanical fallow was maintained, in the 2nd year, turf was sown which was successively mown as necessary. After tree plantation, trees were equally irrigated according to the indication of tensiometers. Every year, equal standard fertilization for young orchards, as well as prophylactic treatments against diseases were applied.

In 2005, spring ground frosts destroyed flowers and the trees did not fructify.

Winter in 2006 was very severe; frosts damaged young shoots and flower buds, so the trees did not fructify in this year either. In spite of a careful protection against diseases (November 2005 – Miedzian 1%; March 2006 – Karpene 0.5%), in this spring, there appeared some symptoms of leaf curliness [Taphrina deformans (Berk.), Tub.] and bark and wood diseases. The symptoms were assessed with the consideration of different methods of soil mulching in tree rows. The degree of tree infection by T.d. was determined by the number of sick leaf rosettes on each tree. The number of branches dying on the tree with symptoms of bark and wood diseases caused by different pathogens such as Pseudomonas syringae van Hall., Leucostoma personi (Nit.) v. Hohn, Leucostoma cincta Fr. V.Hohn, Monilinia laxa, Monilinia fructigena, Clasterosporium carpophilum, Aderh. were counted as well.

Every year, the growth was assessed by the basic parameters: tree trunk diameter increment, TCSA increment and the height and projection of tree crowns (quotient of 2 width values). The results were statistically elaborated by analysis of variance in factorial experiments STAT program. Significant differences were identified by Duncan’s test at the significance level of a = 0.05.

RESULTS AND DISCUSSION

The presented studies have shown that different thicknesses of ‘Fantasia’ nectarine tree cuttings had no significant effect on their growth expressed by the discussed parameters, but only in two years after planting. Both the annual TCSA increments and the tree crown heights and projections were comparable independent of the thickness of the planted trees (Tables 1 and 2). The mean TCSA increment of trees after the 1st year amounted to 4.12 and 4.08 cm², after the second year, it was 9.72 and 10.26 cm², after the third year, it was 11.66 and 11.07 cm². The differences were insignificant. However there were differences in height of tree crowns, but really in third year after planting. The height of tree crowns on thicker trees (>13-15 mm) was mean 2.79 m, but for planted trees with less diameter (11-13 mm) only 2.60 m (Table 1). These differences were higher for trees mulched with fibre sheets.

Similar differences only in third year after planting were for crown projection of trees. Crown projection of trees planted with higher diameter (>13-15 mm) was reaching 4.88 m² but for trees with less diameter only 4.11 m² and was significantly lower. Therefore, the results obtained by Bielicki et al. [1], who reported that the quality of nursery material had an effect on the growth of apple trees in the first years after orchard establishment, was not confirmed in our studies. In our experiment, most probably small differences in tree thicknesses were quickly levelled in the good soil conditions and due to careful cultivation. Thus, the statement of Poniedziałek [9] that the quality of nursery material has a short-lasting effect on the growth of young trees in orchard has found a confirmation.

The mulches applied in our experiment exerted a good protection against weeds. Single weeds growing out from the fibre sheet were manually removed and there was no necessity to use herbicides. The mulch of mowed grass was spread again under trees in spring of the 3rd experimental year; next to the mulch, herbicides were applied in tree rows every year. The type of mulch had a distinct effect on the growth of young trees in the orchard, but only in first and second year after plantation. In the first 2 years, the trees mulched with fibre sheets grew more intensively than those mulched with mown grass. Both the TCSA increment and the height and projection of tree crowns were greater in case of fibre mulch than in case of mown grass (Table l). The TCSA of trees mulched with fibre sheets was 1.45 cm² after the 1st year, and in case of trees mulched with mown grass, it was only 1.19 cm²; after the 2nd year, analogically, greater TCSA increments were shown by trees mulched with fibre sheets (3.31 cm²) than those mulched with mown grass (2.84 cm²), but it wasn’t significant. After 3 year these differences levelled and mulch type has no effect for TCSA increment (Table 1).

Similarly, crowns of trees mulched with fibre sheets were higher (1.87 m) than those mulched with mown grass (1.47 m). But after 3 year there weren’t differences in height trees mulched with different types of mulches (Table 2).

Still more distinct were differences in the 2-years trees crown projection (2.14 m² and 1.66 m² respectively) (Table 2). Crown spread of 3 years trees leveled and there wasn’t significant effect of mulch type for their growth (Table 2). In the experiment of Mika and Krzewińska [7], different results were obtained; among many different mulches, fibre sheets had the highest tendency to develop weeds and did not show any positive effect on the growth of young apple trees. Szewczuk [10] reported that in result of mulching fruiting trees, on 1-year old increments, like, e.g. peach trees, there existed an interdependence between the vegetative growth and yielding.

In the discussed experiment, the effect of mulches was levelled by the applied tree irrigation, but the purposefully applied homogeneous fertilization significantly differentiated the tree growth. We want to find the answer to the question whether and from which year after plantation, the mulch of mown grass in result of a progressing process of its mineralization would supply an increased organic matter mass to the soil making mineral reserves available to the trees. Beneficial effect of organic mulch for growth of young nectarine trees was visible only after 3 year, it’s not to know if such tendency will stay. The studies will be continued.

Differentiated mulching of the rows of young nectarine trees had no effect on leaf infection by Taphina deformans (Berk), Tub. and on the appearance of bark and wood diseases symptoms.

CONCLUSIONS

1. Small differences in the thickness of planted ‘Fantasia’ nectarine trees differentiated only some growth parameters. There weren’t differences in TCSA in 3 first years their growth in orchard. However there were differences in height and projection of crown 3 year trees. Higher and more spread trees were these thicker (>13-15 mm) than weaker (11-13 mm) during plantation.

2. Mulch type in tree rows had a significant effect on the growth of young trees in the orchard, but only in 1 and 2 year. Fibre sheets created more favourable conditions for tree growth than mown grass; the trees were distinguished by a more intensive growth. After 3 year differences leveled.

3. Mulch type had no significant effect on the degree of tree infection by Taphrina deformans (Berk), Tub. and on the appearance of bark and wood diseases.

REFERENCES

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Accepted for print: 25.06.2007

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