DYNAMIC OF STARCH CONTENT IN GRAFTED AND UNGRAFTED MATERIAL OF GROUND COVER ROSES DURING WINTERING PREPARATION

Abstract

Rose-trees are widely used for planting of greenary. It is literally manmade group. These plants were grown specially for home landscaping and stairs stands. 

Buds grafting of different groups, which are characterized as continuous flowering, are used for growing rose-trees. «Rose-trees» are very spectacular.  We need graftings by sprouts at a height of 1-1,7 m. to get such rose-trees, hybrid tea roses, climbers, ground cover roses. Rose-trees in the shape of miniature roses with a height of 0,5 m. are also made.

Most  of roses for gardening are sensitive to low temperatures and  they do not always survive in winter conditions. It is thought that their graftings for enduring kinds of roses can make for both of increasing of their winter hardiness and landscape improvement. It is known about influence of rootstocks on different characteristics of grafting material. So, it was determined, that type of rootstocks doesn’t influence on chlorophyll content in the leaves, but it can provide carbohydrates accumulation  in them. It is also known about influence of rootstocks on winter hardiness of grafting material’s horticultural crop.

Starch analysis in different plant tissues is used for diagnostic of winter hardiness and frost resistance of woody plants. But it is known, that hydrolysis of starch in winterhard garden plants is occurred early than in sensitive to frost ones.

Studying the dynamics of starch accumulation during transition from growing season to dormant period of different kinds and groups of roses shows that this index is significantly changed during winter measures. However, level of these changes is different. Starch content in roses which are resistant to low temperatures decreases faster than  in non-tolerant ones.

Group of ground cover roses has special ornamental nature, both the blossoms and fruits, leaves of these plants give amazing impression, they perfectly decorate landscape. Besides these, ground cover roses have very full blossom and they are very frost resistant. The most part of ground cover roses is wintering under snow, only some kinds need small covering.  However, this group of plants can’t survive in some periods of low temperatures.

As it was said early, now it is widely practiced cultivation of rose-trees which are grafted on Rosa canina. We can use others resistant kinds of roses as a rootstock, such as Centifolia rose. Influence of this rootstock on ability for rose-trees wintering haven’t studied yet.

Aim of this work was studying the dynamics of starch accumulation  during transition from the growing season to dormant period in ground cover roses’ terminal sprouts grafted on Centifolia rose and on own’s roots.

To study this question, we used annual sprouts of ground cover roses of such varieties as Red Fairy, Swany and Rosenberg which were grafted on Centifolia rose, and terminal sprouts of ungrafted material of ground cover roses of the same cultivars and Centifolia rose with pink blossom.

Vegetative propagation of ground cover roses was made by bud grafting on annual shoots of  Centifolia rose in 2011 by practical standarts.

An amount of starch in annual sprouts of ground cover roses was determined by the reaction with iodine in potassium iodide solution. The starch determination was conducted in four repetitions from September to November 2012 and from August to October 2013.

The change degree of starch content during preparation for winter 2012-2013 was determined according to the formula: С = A – В/А х 100, where А – amount of starch content in September 2013 or in October 2012, В – amount of starch content in October 2013 or in November 2012.

In our work, we analyzed the level of changing starch content in ground cover roses such as Red Fairy, Swany and Rosenberg, grafted to Centifolia rose, and also in ground cover roses of the same cultivars which had own roots. Centifolia, which is one of the most resistant to low temperatures among all roses,  was used as a rootstock.

Inoculation was done in summer 2011, but in 2012 from September to November and in 2013 from August to October annual sprouts of ground cover roses were taken to determine starch content in them after growth from grafted and ungrafted material.

In 2012 the most starch content in annual sprouts of ground cover roses on their own roots was in September or in October depending on cultivar. If  Swany and Red Fairy  varieties had the most starch content in September, Rosenberg  had the same in October. Index of starch content for all cultivars was lower than in other months in November during transition to dormant period. So, Rosenberg  had lowered index of starch content in 3 times in November in comparison with October, but Red Fairy and Swany – had index in 1,8-2 times lower in comparison with September. The same tendency of decreasing starch content in November in comparison to September or October we can see in grafted material to Centifolia rose for these 3 varieties of ground cover roses.

In 2013 index of maximum starch content significantly exceeded the same index  in 2012. We can see the most part of starch content in sprouts of ground cover roses both on their own roots and grafted on Centifolia only in September. Level of starch content is significantly decreased in October. That’s why starch content of  Rosenberg, Red Fairy and Swany on their own roots decreased in October almost in 1,5-2,5 times in comparison with September. Decreasing of starch content in October in comparison to September we can see in grafted material as well.

However, level of starch content changing in grafted material and plants, which grew on their own roots, is rather different. We can see the decreasing of carbohydrate content in all researched cultivars of groundcover roses which had both their own roots and were grafted on Centifolia rose in November 2012 and in October 2013.  According to this, level of changings in ungrafted material is comprised  from 18,54 % to 27,63 % in Swany and from 61,44 % to 65,46 % in Rosenberg. Grafted material has significant difference between maximum and minimum levels. So, Swany has changings in 49,05-71,07 %, but  Rosenberg achieved more than  80,0 %.

So, these results show that decreasing of starch content in annual sprouts of ground cover roses of different cultivars which are grafted on Centifolia from August-September to November 2012 and from September to October 2013 is more rapid than in ground cover roses on their own roots. More intensive hydrolysis of starch in grafted material can provide better survival in winter, especially due to hardiness of grafted roses.

As it was mentioned before, in 2013 in contrast to 2012 we could see decreasing of starch content both in own ungrafted roses and roses which were grafted on Centifolia rose. It can be connected with the changing of winter conditions, which could tell us about early cold weather in 2013.

So, significant difference was determined during studying the dynamics of starch content in grafted and ungrafted material of ground cover roses during period of preparation for winter. And, starch hydrolysis in ground cover roses which were grafted on Centifolia rose was more intensive than in ground cover roses on their own roots.