Comparative study on compatibility and growth response of pear varieties on different rootstocks at nursery

Grafting is an asexual method of reproducing fruit plants. The selection of proper rootstock and suitable variety is imperative in order to assure scion and root stock compatibility. Therefore, the present experiment was carried out to evaluate the comparative study on compatibility and growth response of pear varieties on different rootstocks at nursery of the Agricultural Research Institute (North), Mingora Swat, Pakistan during the year 2014. Six pear cultivars (four exotic such as William, Santa Maria, Hosuai and Shinsui and two indigenous such as Khan Tango and Shaghuri) were grafted on two rootstocks (Quince and Pyrus pashia L., locally known as tangai). Pear varieties, rootstocks and their interaction showed significant variation for all the studied attributes. Variety William showed higher graft take success %, plant height, number of shoots plant and survival percentage. However, lower number of graft take success %, plant height, plant diameter, number of shoots plant and survival percentage were observed on Quince rootstocks. It was concluded that pear variety William could be grafted on Quince rootstock for high graft take success and better growth response.

The current study is focused to evaluate the compatibility and graft take success of different pear varieties on two rootstocks.

Materials and method
An experiment on "comparative study on compatibility and growth response of pear varieties on different rootstocks" was carried out at the Agricultural Research Institute, Mingora, Swat (Pakistan) during winter 2014.The aim of the study was to test the compatibility of pear cultivars to different rootstocks.The experiment consisted of two factors such as cultivars and rootstock.Six cultivars namely William, Santa Maria, Hosai, Shinsui (exotic), Khan Tango and Shaguri (indigenous) were grafted on two rootstock such as Quince and Pyrus pashia L., locally known as tangai.The experiment was carried out in Randomized Complete Block Design (RCBD) with three replications.Scions and rootstock of similar size were selected.Tongue grafting was practiced in the month of February, 2014 and were planted in the field on the same date.Row-to-row and plant-to-plant distance was kept 60 and 30 cm, respectively.The data on vegetative attributes were recorded in December, 2014.Percent graft take success was evaluated by the successful sprouting and growth of scion by the formula given as: %Graft take success= Number of successful graft × 100 Total number of plants grafted Whereas, plant height was determined in cm with the help of measuring tape, diameter was recorded in mm by the use of digital Vernier caliper and branches per plant were counted in each sprouted scion.

Statistical analysis
The data noted were subjected to analysis of variance (ANOVA) and least significant difference (LSD) test at 1% probability was used for mean differences [8].

Results and discussion
Grafts take success (%) Changes in pear graft take success % due to varieties and rootstocks are reported in Table 1.Significant variation was observed in graft take success % due to verities and rootstock.The V x R interaction was also found significant.William variety resulted in higher graft take success (88.94%), followed by Khan Tango variety (80.44%) while graft take success % was lower in plots sown with Shinsui variety (65.27%).Moreover, Quince rootstock resulted in higher graft take success (84.46%) as compared to Local (Tangai) variety (69.40%).The V x R interaction revealed that the performance of all varieties except Shinsui were superior on Quince root stock than Local root stock (Figure 1).However, Shinsui showed similar result for graft take success % on both root stocks.Overall, higher graft take success % was observed in Shaguri variety grafted on Quince root stock.High graft take success in Quince might be due to the compatibility of scion with rootstock as the genetic makeup of each scion and rootstock varies.Significant

Plant height (cm)
The significant results showed that maximum plant height (73.69 cm) was exhibited by pear varieties grafted on Quince, while the minimum plant height (60.00 cm) was recorded on rootstock Taangai.Pear varieties also showed significant difference, where more plant growth (91.62 cm) was recorded in pear variety William, while Shinsui variety of pear showed the lowest plant height (31.82 cm) (Table 1).As concerned interaction

Number of shoots plant -1
The significant data regarding number of shoots plant -1 indicated that maximum number of shoots plant -1 (2.77) were produced on rootstock Quince.However, local (Taangai) exhibited less number of shoot plant -1 (2.40).In pear varieties William produced maximum number of shoots plant -1 (5.50), which significantly varied from Shinsui (3.00).The minimum number of shoots plant -1 (1.30) were observed in pear variety Shaghuri (Table 1).
The interaction between varieties and rootstocks showed more number of shoots plant -1 in pear variety William, grafted on Quince rootstock.While the grafting of pear variety Shaghuri on Quince produced the least number of shoot plant -1 (Figure 4).
According to [19], apple variety on dwarf rootstock produced more shoots as it has the habit of forming bush and espalier.The more shoots may also be due to the maximum plant growth.Moreover, different varieties and rootstock has different kind of growth habit that might have affected number of shoots.

Survival percentage (%)
The significant data showed that maximum survival percentage (55.91%)was observed on Quince, while local (Taangai) rootstock showed least survival percentage (48.51%).Pear variety William showed maximum survival percentage (73.10%).The lower survival percentage (44.55%)was observed in pear variety Santa Maria (Table 1).The interaction between varieties and rootstocks showed more number of shoots plant -1 in pear variety William, grafted on Quince.
While the grafting of pear variety Santa Maria on Quince rootstock produced the least number of shoot plant -1 (Figure 5).Survival percentage of graft was highly affected in mango by varieties and rootstocks [20].Rom and Carlson [2] grafted various varieties of pear on Quince and found significant variation for survival percentage and concluded that grafting is a best way to propagate seedlings of quince which results in high graft survival.

Conclusions
On the basis of the study, it is concluded that variety William resulted in higher graft take success %, plant height, number of shoots plant -1 and survival percentage.Furthermore, more number of graft take success %, plant height, plant diameter, number of shoots plant -1 and survival percentage were observed on Quince rootstocks.Therefore grafting variety William specifically and other varieties in general on Quince root stock is recommended for producing true to type pear nursery plants with improved growth at highest rate of success.

Authors' contributions
Introduction Pears (Pyrus communis L. and Pyrus pyrifolia L.) are important pome fruit, belongs to family Rosaceae.In Pakistan, pear orchards are found on the terraces or hilly areas and in the plan of Khyber Pakhtunkhwa like Mardan, Peshawar and Hazara.Pear is generally propagated through asexual or vegetative mean in which grafting and budding is the most appropriate method of propagation.In Pakistan the farmers use whip and cleft grafting.Farmers use seeds of Tangai (Pyrus pashia L.) and Quince as a rootstock [1].East Malling Research Station found Quince as a rootstock, which is used for dwarfing pear cultivars [2].In the recent years, interest in the introduction of new pear varieties has been emerged, which is very much important for opening new ways of trade and to fulfil the demand of consumers [3] New vistas has been opened with the rapid technology development of rootstock (propagation of asexual/clonal rootstock) and nursery of fruit trees [4].Several factors are identified, which may affect success of grafting in the woody species like season, environment, grafting techniques, graft capability among scions, rootstocks and genotypes.Techniques and season of grafting seem to be useful for the purpose of graft success in various genotypes [5].Different rootstocks of pear and quince have been used for the production of pear on commercial scale.Recommendation of Quince as a rootstock is useful for quality fruit production and due to the nature of small size of tree, harvesting and other cultural practices are easy to manage [6].The rootstocks of Quince are extensively used for various varieties of Pear.Several varieties of pear showed incompatibility when grafted on Quince [5, 7].

Figure 1 .
Figure 1.Graft take success of pear varieties as affected by rootstocks

Figure
Figure 4. Number of shoots plant -1 of pear varieties as affected by root stock

Table 1 . Graf take success (%), plant height (cm), plant diameter (mm), number of shoots plant -1 and survival percentage (%) of pear graftage as influenced by varieties and rootstock Pear varieties Graf take success
variation was recorded in graft take success of various apple cultivars [9].The results are also supported by [10], who investigated high bud take success in nursery plants of apple.

Plant height (cm) of pear varieties as affected by rootstocks
more plant height was recorded in pear variety William, when grafted on Quince.However, the grafting of pear variety Hosai on Local Taangai (Pyrus pashia L.) gave the least plant height (Figure2).

Survival percentage (%) of pear varieties as affected by rootstock
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