Growth response of olive cultivars to air layering

The olive (Olea europaea saliva L.) has been little studied for its genetic improvement due to slow rate of seed germination, long juvenile phase and pre-vailing self-incompatibility. That’s why this study was conducted to assess the “Response of different olive varieties to air layering” during July, 2016 at Olive Research Farm Sangbhatti, Agricultural Research Institute (ARI) Tarnab, Peshawar, Pakistan. Air-layering was done in July on five olive cultivars (pendalino, coranica, chetoui, leccino and local variety) using rendomized complete block (RCB) design having three replications. Our findings revealed significantly different results for days to rooting, number of roots plant, root length, root diameter and root weight in response to air layering. Olive cultivar pendalino took maximum days to callus formation and rooting and produced longer and denser roots, while with respect to root diameter and weight chetoui was observed best cultivar. Local verities took minimum days to root and callus appearance and established earlier compared to others. On the basis of the aforesaid results variety chetoui performed best in terms of rooting. Thus it is recommended that in area with sufficient water availability local cultivar should be grown while cultivar chetui should be grown in area with scares water availability because of its good rooting system and produce relatively good yield than others cultivars.

Olive is propagated by sexual (vegetative) as well as asexual (seed) methods.Propagation of olive through sexual mean is not generally recommended, for the reason that seedlings are not true to type and it will take much more time to bear fruits [5].Asexual or Vegetative propagation methods can possibly be the most usually used commercial method of propagation in olive.Asexual propagation methods consists of cutting, budding, grafting and air-layering [6], but mostly propagation is done through air-layering because it takes comparatively less time.Air layering is usually done in the months from June-August.Branches from well-developed trees, free from pests and diseases are selected for air-layering.A branch of 5-10mm in diameter is selected and bark of ½-1 inch is removed, covered with garden soil and any other rooting medium and then wrap with polythene film.When a good ball of roots has formed, the branch is then cut off below the wrapped soil after which is generally placed in larger tube or pot to become more firmly established before being set out permanently [5].[7] Air layered one year old shoots on several dates between July-November and observed rooting percentage and establishment (in three cultivars), survival after transplanting (in two cultivars).In air-layering shoot is not buried in soil, first a small cut is given to shoot and then sphagnum moss is wrapped through polythene around the cutting portion.Since cutter portion is exposed not buried in soil, you may see root development, when roots develop detach shoot from parent plant and plant it [8].The olive is major agricultural significance of Mediterranean area as the source of olive oil and it is one of the three core constituents in Mediterranean cuisine.Olive is a rich source of vitamin E and contains a large amount of sodium.Olive contains 75% water 4% carbohydrates and 1% protein [9].Black olives are a good source of iron which is important for the transport of oxygen in red blood cell [10].It also contain copper which is essential mineral is often lacking in the typical western diet.Numerous varieties have been tried in the state with cold hardiness being the key selection factor.Not all varieties perform the same at all locations.It may be that one variety does well for your neighbour, but just across the street at your farm it does horribly.Differential varietal performance has been noted among adjacent or-chards.Therefore this study was initiated to find out the response of different olive varieties to air layering at the agro climatic conditions of Peshawar region.

An experiment was executed at Olive
Research Farm Sang Bhatti, to study the response of different olive varieties to air layering.Five different varieties Pendilino, Leccino, Karonika, Chetuei and control (local verity) were evaluated in field experiment using randomized complete block (RCB) design with three replication.Sixteen air-layers techniques were practiced in each verity of olive plant keeping 80 (16 x 5) plants per replication.In order to initiate rooting in olive cultivar chetuei, branches a circular strip of bark having 3 cm size was completely removed just below the buds from one year old shoots.The branches used for air-layering had 1.5 m length and pencil size thickness.Seven years old plants have been selected for the experiment.A heavy mass of prepared media was tightly wrapped around layered branches readily after the removal of bark to reduce moisture evaporation from the opened portion.The media were covered with polyethylene sheets to make sure that the media remain intact.After the air-layering all the plants were frequently irrigated.Data were collected after 20 days.The branches which have effective development of roots in media were cut off carefully below the layered potion from parent plants and data were recorded for different parameters.All other cultural parameters were kept uniform for all the treatments during this way of experiment.

Data collection
Total number of days to callus development was counted from the date of air-layering to the development of callus.Total number of days to root appearance was calculated from the date of layering to the appearance of roots.To record the number of roots per air-layered shoot plant were cut and the media attached with roots was washed away with water and was removed completely.Subsequent to cleaning, the length of roots was measured in centimeters with the help of measuring tape from the point of emergence to the apex of most noteworthy root.The diameter of roots was measured with the help of vernier caliper in millimeter subsequent to cleaning the roots from media with water.Weight of the roots per air-layered shoot was measured in grams by digital balance after proper washing and processing.

Statistical analysis
The noted data was analysed statistically by using statistical software GenState 8.1 [11].Upon least significance difference (LSD) test have been used for means comparisons to find out the significant components of the treatment means [12].

Results and discussion Days to callus formation
Callus is a mass of immature plant cells which can differentiate into mature tissues, depending upon the relative concentrations of plant growth hormones present.Callus can develop form explants in laboratory tissue culture experiments but also occurs naturally at the end of cut or wounded surfaces of shoots and roots.Callus development was affectively influenced by the growth media in different olive cultivar as presented in figure 1.With respect to the variety variations, we found that the callus induction frequencies are comparatively much higher in variety Pandilno and coranica which took statistically similar time for callus formation while the remaining cultivar took relatively less time.The number of roots per plant was significantly affected in response to different olive cultivar as presented in figure 3. Upon analysis best result was obtained in pendalino cultivar which was alike to coranica and higher than chetouie, while the lowest number of roots per plant was recorded in local variety (3.66 roots per plant) which was similar to leccino.These results similar to [8] who recorded up to 8.30 roots plant-1 .Differences in verities with respect to rooting ability are because of the adjustment of this cultivar to our agro-atmospheric conditions.

Root length (cm)
Root length was statistically influenced by different types of growing varieties (Figure 4).Analysis of variance showed longer roots for pendalino which was statistically equal to corannica and chetoui while the lowest root length was recorded in local control which was 2.1mm.Root length grows down and is very effective in engrossing moisture and nutrient for plant growth and development.The results are not in line with [8] who found maximum root length 7.01 in a verity adjustable to the growing conditions.Thus it may be found that root length of a cultivar may vary depending upon their resistance to moisture stress and adoptability to the agro-climatic conditions.
Introduction Olive (Oleaeuropea L) is from family Oleaceae and cultivated for edible oil and fruits.Olives have not been conventionally grown in Pakistan for the edible oil production, except few areas including plain and hilly [1].It is initiated in the eastern Mediterranean region and its practices started in Spain, Italy and N-Africa later than in the eastern Mediterranean area [2].Olive profitable production is found between 30 o -45 o north and south of equator around the world [3].Pakistan have the same agro climatic condition and soil factors for olive production, due to which have the ability for the tropical, subtropical and temperate fruit trees can be grown.Olive can be grown successfully in sub-tropical mountainous region of Khyber Pakhtunkhwa, Baluchistan and northern area of Pakistan [4].

Figure 1 .
Figure 1.Days to callus of different variety of olive.Mean with different letters are significantly different (5% level of significance), CV= 7.39 and LSD=3.3 Days to rootingDays to rooting were significantly influenced by various types of olive varieties as presented in figure2.The rooting were recorded in cultivar (Pandilino) which was 62 days, while the lowest were recorded for local verity.Chetoui took such a time to rooting which was statistically similar to cultivar Leccino and Coranica.It shows that the best result of days to emergence were recorder in local variety.This variation in the sprouting is due to the fact that cultivar sprouted earlier depending upon length of cuttings and nature as reported by [13] who also recorded different results in cultivated and wild olive cuttings.

Figure 2 .
Figure 2. Days to rooting for different varieties of olive.Mean with different letters are significantly different (5% level of significance), CV= 4.05 and LSD= 4.32

Figure 3 .
Figure 3. Number of roots per plant for different varieties of olive.Mean with different letters are significantly different (5% level of significance), CV= 38.85 and LSD=4.32

Figure 4 .
Figure 4. Root length and different varieties of olive.Mean with different letters are significantly different (5% level of significance),CV= 13.75 and LSD= 0.87

Figure 5 .
Figure 5. Root diameter (mm) of different varieties of olive.Mean with different letters are significantly different (5% level of significance) CV= 4.18 and LSD= 0.10