Abstract: An experiment was conducted to study the effect of variety and different nursery conditions on the survivability of air-layers of two varieties of guava at the Germplasm Centre (GPC) of Fruit Tree Improvement Project, Department of Horticulture, Bangladesh Agricultural University, Mymensingh during the period from August 2001 to July 2002. Planting air-layer after detached from the mother plant and planted under different nursery conditions showed significant variation in success of air-layers. Open condition (both layers in poly bag and layers in situ) increased the percentage of survivability then under shade condition. Layers in situ (both shade and open condition) increased the number of shoots and leaves of the detached air-layers than layers in polybag. The highest percentage of survivability (100%) was observed from layers in situ under open condition which was statistically similar to layers in polybag under open condition.
INTRODUCTION
Guava are generally propagated by air-layering. Most of the cases, after separation of air-layers from the mother plant, it was found that certain percentage of layers die due to detachment shock injury, handling and other factors particularly low humidity, high temperature, scorching sunlight etc. Vyas[1] reported that time of operation, shoot thickness, shoot position, rooting media, wrapping material, use of growth regulators, pruning and shade treatment after separation of air-layers also plays an important role on the success of air-layers after detachment. Providing some shade and protection from the wind followed by cut back of the top of the branch, so as to secure a proper proportion of leaves to root are also advocated for maximum survival of the detached air-layers in case of guava and litchi[2].
Keeping all stated facts in mind, the present experiment has been designed to investigate the different nursery conditions of guava air-layers on their survivability and growth performance.
MATERIALS AND METHODS
The present research work was carried out at the Germplasm Centre of Fruit Tree Improvement Project (FTIP), Bangladesh Agricultural University, Mymensingh during the period from August, 2001 to July, 2002 to study the effect of different nursery conditions on the survivability and growth performance of air-layers of two varieties of guava. Two varieties namely Swarupkathi (V1), Madhuri (V2) and four different conditions in the nursery maintained for layers after detachment namely layers in polybag under shade condition (M1)-Artificial shade with coconut leaves, layers in polybag in open condition (M2), layers in situ under shade (M3), layers in situ in open condition (M4) were practiced on the detached air-layered shoots.
For guava air-layering healthy, disease free, lateral shoots of approximately 1-year-old and preferably from previous years growth was selected. The approximate diameter of branches were taken as 1.0 to 1.5 cm and this was done according to Ruehle[3]. In the month of August, 2001 guava air-layer was done by removal of 3 cm long bark cylinder and then scrapping the exposed wood to remove the cambium layer from above them with the help of a sharp knife. The wood was then covered with moistened rooting medium. To cover the mixture completely a 0.65 m2 piece of clear polyethylene sheet was used. The ends of the wrapping materials were carefully tied up thoroughly with rope and left for rooting.
A well leveled land was selected for the layers planting. The nursery bed was prepared before detachment of the layer from the mother plant. The nursery bed was prepared by opening the soil with a spade and followed by laddering to break the soil clods and to level the surface before planting. No chemical fertilizers were used in the soil. Well rotten cowdung (20 m t ha-1) was applied at the time of land preparation. The bed was cleaned by collecting and removing weeds, stubbles, stones etc. After detachment from the mother plant, pruning of 75% leaf of each layer, i.e. allowing 25% of leaves to remain with the layers. Then the layers were planted in nursery bed directly and planted in polybag. Layers of guava and litchi were planted in the afternoon at a spacing of 25x25 cm and immediately after planting watering was done uniformly by watering can. Some of the layers were planted in open air and some were placed in shade condition. Shading was provided with coconut leaves at a height of 3 m after planting to protect the layers from excessive rainfall and sunlight. Proper care was taken in the nursery bed so that, the growth of air-layers was adequate.
The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications number of shoots and no of leaves per successful layers were recorded at 15 days interval starting from 35 days after planting and was continued up to 320 days. Percentage of success in the survivability of detached rooted layers was counted after 2 months from the date of planting, the number of successfully air-layers (root initiation) were counted after 35 days from the date of operation.
The collected data on different parameters under different experiments were statistically analysed wherever necessary. The mean for all treatments were calculated and analyses of variances for all the parameters/characters under consideration were performed by F variance test using MSTAT program. The significance of difference between pair of means was expressed as Least Significant Difference (LSD) test.
RESULTS AND DISCUSSION
Main effect of variety on the growth, success and survivability of detached
air-layers
Percentage of survivability of detached air-layers: The data obtained
from the experiment showed significant variation between the varieties Swarupkathi
(V1) and Madhuri (V2). The variety Swarupkathi (V1)
survived at highest percentage (97.41%) in the nursery bed, than the Madhuri
(V2) (88.98%) (Fig. 1).
Number of shoots per layer: Number of shoots at different days due to the influence of two varieties was highly significant except 250 and 265 DAP. The variety Swarupkathi (V1) produced the highest number of shoots per layer at different days than Madhuri (V2) (Table 1).
Number of leaves per layer: Two varieties had significant influence on the number of leaves at different days after planting. The variety Swarupkathi (V1) produced the maximum number of leaves at different days and the lowest number was obtained from the variety Madhuri (V2) than Swarupkathi (Table 2).
| Table 1: | Main effect of variety on the number of shoots of guava layerage at different days after detachment from the mother plant |
| Table 2: | Main effect of variety on the number of leaves of guava layerage at different days after detachment from the mother plant |
| ** = Significant at 1% level, NS = Non-significant | |
| Fig. 1: | Effect of variety on the percentage of survivability in case of nursery condition of guava layerage at 60 DAP. Vertical bar represents LSD at 1% level |
| Fig. 2: | Effect of nursery condition on the percentage of survivability of guava layerage at 60 DAP. Vertical bar represents LSD at 1% level |
Main effect of nursery condition
Percentage of survivability of detached air-layers: It was observed
that the effect of different nursery conditions on the survivability of guava
air-layers were highly significant. The highest percentage of survivability
(100%) was observed from layers in situ in open condition (M4)
at 60 days after planting which was statistically similar to layers in polybag
in open condition (M2) and the lowest percentage of survivability
(78.14%) was observed from layers in polybag under shade condition (Fig.
2). This result differs with Voltolini[4] who suggested to grow
the rooted layer under 70% shade. Percentage rooting and survival were highest
(94.63%) when layers planted in the nursery bed directly under open condition
than polybag in open condition (78.14%). The present result are in agreement
of Kamleshkar and Jain[5].
Number of shoots per layer: The effects of nursery condition method on the number of shoots at different days after planting were highly significant. Layers planted in situ in open condition (M4) produced the highest number of shoots per layer at different days after planting followed by layers in situ under shade condition (M3), polybag in open condition (M2) and polybag under shade condition (M1) (Table 3).
Number of shoots per layer was decreased when layers were grown in shade condition compared to full sun (0% shade) due to the lower phenolic substance contents. Layers in heavy shade having poor root system, number of shoots per layer was also decreased. Similar result was also reported by Vinzant and Criley[5], Voltolini[4]. When layers grown under nursery bed condition (in situ), the number of shoots per layer was also increased than in polybag due to proper aeration, high moisture content, proper nutrient uptake etc. This result was also supported by Leon et al.[6] who stated that in situ condition significantly increased the number of shoots per layer.
Number of leaves per layer: Number of leaves was recorded at different days and it was observed that there was highly significant variation for different nursery conditions at different days. The highest number of leaves was produced when layers were grown in situ in open condition (M4) and the lowest number of leaves per layer was produced when layers were grown in polybag under shade (Table 4). When layers grown under in situ condition the number of leaves per layer was increased than in polybag method due to high moisture content, proper aeration but number of leaves was decreased under full shade condition over open condition in nursery bed. Similar result was also reported by Leon et al.[6].
Combined effect of variety and nursery condition on growth, success and survivability of guava air-layers.
Percentage of survivability of detached air-layers: Combined effect of the variety and the nursery condition showed highly significant variation on the survivability of detached guava air-layers.
| Table 3: | Main effect of nursery condition on the number of shoots of guava layerage at different days after detachment from the mother plant |
| Table 4: | Main effect of nursery condition on the number of leaves of guava layerage at different days after detachment from the mother plant |
| ** = Significant at 1% level, M1 = Layers in polybag
under shade condition, M2 =Layers in polybag in open condition M3 = Layers in situ under shade, M4 = Layers in situ in open |
|
| Table 5: | Combined effect of variety and nursery condition on the number of shoots of guava layerage at different days after detachment from the mother plant |
| ** = Significant at 1% level, V1M1 = Swarupkathi x Layers in polybag under shade condition , V1M2 = Swarupkathi x Layers in polybag in open condition, V1M3 = Swarupkathi x Layers in situ under shade, V1M4 = Swarupkathi x Layers in situ in open, V2M1 = Madhuri x Layers in polybag under shade condition, V2M2 = Madhuri x Layers in polybag in open condition, V2M3 = Madhuri x Layers in situ under shade, V2M4 = Madhuri x Layers in situ in open | |
| Table 6: | Combined effect of variety and nursery condition on the number of leaves of guava layerage at different days after detachment from the mother plant |
| ** = Significant at 1% level, V1M1 = Swarupkathi x Layers in polybag under shade condition, V1M2 = Swarupkathi x Layers in polybag in open condition, V1M3 = Swarupkathi x Layers in situ under shade, V1M4 = Swarupkathi x Layers in situ in open, V2M1 = Madhuri x Layers in polybag under shade condition, V2M2 = Madhuri x Layers in polybag in open condition, V2M3 = Madhuri x Layers in situ under shade, V2M4 = Madhuri x Layers in situ in open | |
Highest percentage (100%) of survivability was obtained from the variety Swarupkathi and layers planted in situ in open condition (V1M4) treatment combination which was statistically similar to Swarupkathi and layers in situ under shade condition (V1M3), Swarupkathi and layers in polybag in open condition (V1M2), Madhuri and layers in situ in open condition (V2M4), as well as Madhuri and layers in situ under shade condition (V2M3). The lowest percentage (66.66%) survivability was obtained from Madhuri and layers in polybag under shade condition (V1M1) (Fig. 3). The interaction effect of different nursery conditions and varieties was found to be significant.
| Fig. 3: | Combined effect of variety and nursery condition on the percentage of survivability of guava layerage at 60 DAP. Vertical bar represents LSD at 1% level |
Number of shoots per layer: The combined effect of variety and nursery condition was found to be significant in respect of number of shoots per layer at different days. At different days after planting the maximum number of shoots per layer was obtained from the combination of variety Swarupkathi and layers in situ in open condition (V1M4) and minimum from variety Madhuri and layers in polybag under shade condition (V2M1) (Table 5). There was significant interaction between varieties and different nursery conditions for number of shoots per layer at different days after planting.
Number of leaves per layer: The combined effect of nursery condition and variety was highly significant on the number of leaves per layer. The maximum number of leaves was achieved by the variety Swarupkathi and layers in situ in open condition (V1M4) and the lowest was obtained from variety Madhuri and layers in polybag under shade condition (V2M1) at different days (Table 6). There was significant interaction between the varieties and different nursery conditions.
ACKNOWLEDGMENT
The authors are gratefully acknowledged the financial grant to the FTIP by the Swiss Agency for Development and Cooperation (SDC), Dhaka.