*2.2. Nursery of Scion and Rootstocks*

Cucumber cv Kalaam F1 scion were grafted on four local cucurbitaceous rootstocks by tongue grafting, splice grafting, single cotyledon grafting and hole insertion grafting. Scions were sown in a nursery greenhouse on 25th and 28th of July in 2017 and 2018 in a 200-hole tray and rootstocks were grown in seedling trays with 128 cells (280 × 540 × 40 mm). The seeds of four different rootstocks named as *Lu*ff*a operculata*, *Momordica charantia*, *Cucurbita pepo* and *Lagenaria siceraria* were sown after five days of scion seed sowing. Peat moss and vermiculite ratio 1:1 (v/v) was used as growing media because it sustained better equilibrium of moisture and air which was best for seedlings. 100 g ammonium sulphate, 150 g potassium sulphate, 400 g calcium superphosphate, 50 mL nutrient solution and 50 g of fungicide were mixed for each 50 kg of peat moss. The characteristics of the growing media before seed sowing were: pH-6.7, electrical conductivity EC-0.14 mS cm−1, NO3-15 mg dm3, P-4 mg dm3, K-31 mg dm3, Ca-28 mg dm3, Mg-17 mg dm3 and total nitrogen 0.25% [43]. Nitrogen, phosphate and potassium fertilizer were also applied. The seeds were sown under 28 ◦C mean temperature and 80% relative humidity. The 400 scion plants and 400 rootstocks (100 for each rootstock) were prepared and 200 plants (100 scion and 100 rootstocks) were used in each grafting technique. The experimental treatments, their levels and replication were presented in Table 1. The scion-rootstock were shifted into plastic pots of 8 cm diameter with the same growing media. Before grafting, a laminar flow UV light was used to kill the microbes in the working place [43].

#### *2.3. Grafting Techniques and Procedure*

The four grafting techniques used were splice grafting, tongue grafting, single cotyledon and hole insertion grafting. The different aged seedlings were grafted under the different grafting methods. Grafting method required selection of seedlings that mainly based on its stem diameter. Each grafting technique was applied on 100 scion and 100 rootstocks (25 for each rootstock) with four treatments and five replications.

The scion and rootstock plants were taken out from the seedling tray. The grafting was performed and then the plants were shifted into disposable plastic pots with same growing media and characteristics. In tongue grafting technique (TAG), the plants were 17 and 15 days old (4 mm stem diameter) taken for root-stock and scion gave the best diameter match. The downward and upward slanting cut were made on scion stock and rootstock respectively [32,44,45]. In splice grafting, the 15 day old plants were preferably matched stem diameter that can fits with each other were best fits for that graft union. The rootstock and scion stock were cut slanted at 35◦–45◦ downward and upward respectively [33,34]. The 14 days rootstock and 13 days scion stock fit best for this graft combination in single cotyledon grafting method. The scion was grafted on the stem of rootstock plant [36,37]. The hybrid cucumber scions of 13 days and pumpkin rootstocks of 10 days were best match for grafting. Rootstock was removed just above the false leaf, and the sharpened scion was inserted in it after making a hole between the false leaf interjections with the help of small narrow sterilized wooden sticks [20,38]. The union point was sealed with aluminum wrap and grafting clips. The plastic pots were enveloped with transparent plastic sheet in order to maintain the humidity level around the graft. The plastic sheet was cut from top side after three days in order to allow vertical growth. Grafting plants healing begun after five days and plastic sheet was taken off completely after six days. Plants were supplied water and fertilizer accordingly.

The plants were kept in screen house for eight days after twelve days of grafting. This whole procedure took 30–35 days after transplanting. Transplantation of grafted plants was performed on September 9th and 12th, 2017 and 2018. The grafted plants rows were of 10m in length and 1.2 m in width with 0.5 m distance between plants. Each single treatment consisted of twenty (20) plants in a row. The plants were transplanted keeping union of graft above the soil surface to prevent the development of roots from graft union that may cause infection and plant wilting. The conventional agricultural practices were adopted during the entire cucumber crop production. The cucumber fruit was harvest after 70 days from grafting (35 days after transplanting) and then cucumber fruit was harvested with two days interval. The following parameters were studied during this research study.

#### *2.4. Studied Characteristics*

The plant and fruit growth characteristics were studied to evaluate the compatibility of different grafting techniques applied on four local cucurbitaceous rootstocks and one hybrid cucumber scion.

#### 2.4.1. Plant Vegetative Growth

The plant sustainability after grafting was measured till 30 days after grafting and the measurements were taken for plant vegetative growth 75 days after transplanting. Three plants were randomly selected from each treatment. The mean leaf area (cm2) was measured through fresh weight method. The collected leaves were cleaned and weighted 0.001 g. The 20 disks with known weight were taken and the area of each disk was 1.0 cm2.

$$\text{Leaf area } (\text{cm}^2) = \frac{\text{fresh weight of leaf No.10}}{\text{fresh weight of 20 disk}} \times 20 \times \text{area of disk} \tag{1}$$

The other plant vegetative parameter measured number of leaves, plant height (cm), shoot length (cm), stem diameter/thickness (cm), number of plant branches and chlorophyll content/SPAD values were using SPAD-501 (leaf chlorophyll meter) to estimate the leaves pigments or green color of leaves of 5th leaf (fully expanded) from the top of canopy [46]. At flowering stage flowering time (days), fruiting harvesting time (days) and survival rates (%) were observed. The plant survival rates and mortality were observed after 12 days from the grating by counting the number of plants wilted. The survival rates were recorded till harvesting stage.
