The effect of Tarawat hydrogel and irrigation interval on available water and rooting indices in Nerium oleander.
Oleander (Nerium oleander) is a green area species that used broadly in most cities to create green area for parks hedge, boulevards, highways margin and green belts. Some factors such as long period dormancy of seeds and high amount of hollow and dead seeds reduce germination percentage of the different oleander species. So its vegetative propagation has particular importance for seedling production of the plant [1,12], Replication media of nurseries includes a large coarse minerals portion to raise the proportion of large pores filled with air. But existence of course minerals (such as sand and gravels), which have low water holding capacity and high deep water percolation, cause moisture which is the most important factor in rooting of cuttings, easily be drained. Water depletion could loss irrigation water resources and also reduces the physiological and metabolic processes which are effective in rooting of cuttings , The usage of hydrogel to attract and increase water holding capacity of the green area seedling rooting media is considered recently , Their application in seedling rooting media could eliminate moisture stress and helping adaption of planted crops with environment. The hydrogel also raised the water efficiency and therefore could increase the irrigation interval , Jandagheyan (2001) investigated the effect of polyacrylamide hydrogel and irrigation interval on the rooting of geranium and philodendron. The results showed that with the increasing usage of hydrogels from zero to 50 percent by volume, rooting percentage, plant height, fresh and dry root weight increased. The maximum value of these indices were observed in geranium in 0.3% hydrogel with 6 days irrigation interval and in philodendron in 0.5% hydrogel with 3 days irrigation interval , Ghasemi and Khoshkhole (2007) studied the effect of superabsorbent polymers on irrigation interval and growth and development of Chrysanthemum morifoliumramat. The results showed that using the hydrogel has a significant positive effect on vegetative parameters. All vegetative mean parameters except the ratio of root to shoot did not significantly differ in 0.6% hydrogel in 4 days irrigation interval treatments with control treatment (no hydrogel) in the 2 days irrigation interval , Assareh et.al. (2007) investigated yew rooting and causes of their hard and late rooting of cuttings. Results showed that the highest rooting was in pure sand and absorbent hydrogel in addition of indole butyric acid hormone treatment , Farokhzad et.al. (2009) studied the effect of polyacrylamide polymer and indole butyric acid treatments on rooting of cuttings of Magnolia soulongena. The results showed that the percentage of rooting of cuttings increased from 26.66% in control to 70% in the 3000 ppm indole butyric acid with 0.8% super absorbent treatment , Meghani et al. investigated the effect of media culture on rooting of Bougainvillea glabra cuttings. Results indicated that the highest rooting percentage with an average of %75 was obtained from %50 sand with 0.5% moisture absorbent material . Research conducted by Huttermann et.al. (1999) indicated that with addition of stockosorb hydrogels to soil to 0.4% w/w after 17 days, all 45 seeds germinated. This study aimed to evaluate the application of the hydrogel to supply optimal moisture needed for rooting of Nerium oleander cuttings culture and adjust the irrigation interval to result in the saving of irrigation water.
MATERIALS AND METHODS
In order to investigate the effect of Tarawat hydrogel absorbent and irrigation interval on available water and some rooting of cutting of Nerium oleander indices, an experimental layout consisted of factorial arranged in a complete block randomized design with three replicates and each replication consist of six cuttings was carried out in the crop science--research and breeding to produce plants with ornamental horticulture and green area greenhouse in Isfahan city in 2012-2013. Treatments were four level hydrogels 0 (control), 0.15, 0.3, 0.6% w/w and four irrigation intervals (1, 2, 3 and 4 days). At the bottom of each pot (10 x 10 cm), 1 cm thick of bran was added to helping drainage .Then, the hydrogel treatments and sand mixtures which mix to a depth of 8 cm of pots was poured into the pots. Taking of cuttings of the young shoots were performed in early autumn and about 3 to 4 inches away from the bottom of the cuttings immediately entered the 2/1000 concentration of Benomyl fungicide for disinfection and then were planted in pots cultures. After establishment of cuttings the amounts of irrigation water by 40% allowable depletion of soil moisture for the sand that used in the rooting context, were calculated by the moisture content by volume of the sand field capacity, permanent wilting point and pot sizes and were distributed for each pot and each irrigation interval on the pot surface. While careful monitoring of pots during rooting, factors such as rooted cutting percentage in each treatment, the root fresh and dry weight, root diameter, root length and number of roots in the final of rooting procedure were recorded according to standard measurements , Also at the end of the experiment, samples were taken from the rooting media and the amount of available water was determined from the difference between water content at field capacity and permanent wilting point measured by pressure plates. Statistical analysis of the data of studied plants for the hydrogel rates and irrigation interval was performed by analysis of variance (ANOVA), comparing the mean by the LSD method with using MSTAT-C and drawing diagrams by EXCEL.
Hydrogel application rates and irrigation interval effect on the amount of available water:
The results (Table 1) showed that the main effect of hydrogel application, irrigation interval and interaction of hydrogel application and irrigation interval had a significant effect on available water (pr [less than or equal to] 0.01). The results of mean comparison (Figure 1) showed that different irrigation interval had significant difference about this property, so that the maximum amount of available water related to 1 day irrigation interval and with increasing irrigation interval significantly decreased. Based on the comparison of different hydrogel levels impact on the amount of available water (Figure 1), it was seen that the greatest amount of available water is related to 0.6% hydrogel treatment. Interaction of hydrogel application and irrigation interval on available water showed that the 0.3% hydrogel in 1 day irrigation interval has the highest mean. The minimum amount of available water was relevant to control treatment in 3 and 4 days irrigation interval (Figure 1).
Percentage of rooted cuttings:
Analysis of variance of irrigation interval and hydrogel rates on percentage of rooted cuttings of Nerium oleander are included in table (1). As the results show, the main effects of the use of hydrogels, irrigation interval and interactions effects of hydrogels and irrigation interval applications on percentage of rooted cuttings was significant (pr [less than or equal to] 0.01). A mean comparison of hydrogel rates and irrigation interval application effects on percentage of rooted cuttings is shown in figure (2). As it can be seem the different irrigation interval had a significant effect on the average percentage of rooted cuttings and the highest percentage of rooted cuttings relate to 1 day irrigation interval. Hydrogel application in culture media have a significant effect on average of percentage of rooted cuttings, so that with increasing hydrogel rates from zero to 0.3%, the percentage of rooted cuttings has increased. With increasing hydrogels from 0.3 to 0.6%, the percentage of rooted cuttings was significantly decreased (Figure 2). The interaction between the hydrogel and of irrigation interval on the mean of percentage of rooted cuttings showed that the highest mean of rooted cuttings (83.3%) is relevant lo 0.3% hydrogel with 1 day irrigation interval which with the same amount of hydrogel and 2 days irrigation interval not be significant. The lowest mean of rooted cuttings (15%) was related to control treatment (without hydrogel) in irrigation interval of 3 and 4 days (Figure 2).
The number of roots per cuttings:
The analysis of variance and mean comparison results of number of roots per cuttings grown indifferent percentages of hydrogels are presented respectively in (able (1) and figure 3. As shown in table (1), the effect of different percentages of hydrogel, irrigation interval as well as their interaction on the number of roots per cuttings of Nerium oleander was statistically significant (pr < 0.01). The highest mean number of roots per cuttings related to 1 day irrigation interval and with increasing of irrigation interval this index was significantly decreased (Figure 3). Application of hydrogel effect on the number of roots per cuttings and the highest number was related to application of 0.3% hydrogel and the lowest was related to control and 0.15% of the hydrogel. Interaction of hydrogel application and irrigation interval showed that the highest mean number of roots per cuttings was related to the use of 0.3% of the hydrogel in the 1 day irrigation interval which had not significant difference with 0.3% hydrogel in 2 days irrigation interval. The lowest mean number of roots per cuttings was relevant to control with irrigation interval of 3 and 4 days and 0.15% of the hydrogel with 4 days irrigation interval (Figure 3).
Fresh weight of cuttings root:
The analysis of variance results (Table 1) shoved that the main effects of the application of Tarawat hydrogel, irrigation interval and also interaction of them had significant effect on root fresh weight of cuttings of Nerium oleander (pr [less than or equal to] 0.01).The mean comparison results (Figure 4) showed that different irrigation interval had significant difference about fresh weight of root of cuttings, so that the highest root fresh weight was associated with 1 day irrigation interval and shoved significant decrease with increasing of irrigation intervals. According to mean comparison of different rates impact on root fresh weight (Figure 3). it is understandable that the highest root fresh weight is related to 0.3% hydrogel treatment. Interaction between application of the hydrogel and irrigation interval of the mean weight of roots per cuttings shoved that 0.3% hydrogel in 2 days irrigation interval had the maximum mean that did not have significant difference in 0.3% hydrogel in 1 day irrigation interval. The lowest root fresh weight was in control in 3 and 4 days irrigation interval and also 0.15. 0.3 and 0.6% hydrogel rates for 4 days irrigation interval (Figure 4).
Dry weight of cuttings root:
The results showed that root dry weight was affected by irrigation interval (Table 1), and based on mean comparison the highest cuttings root dry weight was related to 1 day irrigation interval and root dry weight decreased significantly with increasing irrigation interval (Figure 5). The hydrogel rates had a significant effect (pr [less than or equal to] 0.01) on cuttings root dry weight (Table 1). With increasing hydrogels up to 0.3% the root dry weight was significantly increased and the highest root dry weight relevant to 0.3% hydrogel treatment (Figure 5). The results of the mean comparison relating to the interaction of the hydrogel rates and irrigation interval indicated that the highest root dry weight was in 0.3% hydrogel with 1 day irrigation interval which w ere not significantly different in same amount of hydrogel in 2 days irrigation interval. The lowest root dry weight was related to the control in 3 and 4 days interval irrigation that did not show significant difference with 0.15.0.3 and 0.6% hydrogel rates for 4 days irrigation interval (Figure 5).
Root diameter growth:
The analysis of variance and mean comparison results of diameter of root growth in cuttings grown in media impregnated with different percentages of hydrogel rates respectively presented in (able (1) and figure 6. As shown in (able (1), the effect of different percentages of hydrogel and irrigation interval as well as their interactions on root diameter growth of Nerium oleander cuttings was significant (pr [less than or equal to] 0.01). According to the mean comparison (Figure 6), the mean diameter of roots per cuttings in 1 lo 2 days irrigation interval were not significantly difference and this index decreased significantly with increase of the irrigation interval. The maximum diameter of the roots was related to 0.3% hydrogel treatment and minimum was related to control and 0.15% of the hydrogels rates. Interaction of irrigation interval and hydrogel rates had significant effect on root diameter and showed that the greatest root diameter were in 0.3% hydrogel in 2 days irrigation interval and so that was not significantly different with this and 0.6% hydrogel rates in 1 day irrigation interval (Figure 6).
The analysis of variance results (Table 1) showed that the main effects of hydrogel application irrigation interval and also interaction of hydrogel application and irrigation interval had significant effect on root elongation of Nerium oleander cuttings (pr [less than or equal to] 0.01). The mean comparison results (Figure 7) showed the greatest elongation of roots were related to 1 and 2 days irrigation interval and this index significantly decreased with increasing of irrigation interval. Application of hydrogel effect on root elongation so that the maximum root length was related to 0.6% hydrogel treatment which was not significantly different with 0.3% treatment but had significantly different with control and other values. The mean comparison of interaction between irrigation interval and hydrogel rates (Figure 7) showed the greatest root length was related to 0.6% hydrogel with 1 day irrigation interval which there was no significant difference with the same amount of hydrogel in 2 days irrigation interval and 0.3% hydrogel in 1 to 2 days irrigation interval. The lowest mean was relevant to control in 3 and 4 days irrigation interval and also 0.15 and 0.6% hydrogel in irrigation interval of 4 days.
Rooting of Nerium oleander cuttings is an important step in the reproduction of the plant and is sensitive to the lack of moisture. Effect of moisture stress can cause failure or delay rooting that is different based on degree of moisture lack. Studies of hydrophilic hydrogel in rooting media of plants indicated that with quick absorption of water and keeping it. could decrease moisture stress and increase the water absorption efficiency. The amount of this increasing depending on the application of the hydrogel and irrigation interval , The results of this study showed that, in the absence of hydrogel, with increasing irrigation interval from 1 day to 4 days all parameters measured included the percentage of rooted cuttings, fresh and dry root weight, root length, root diameter growth, number of roots per cuttings shoved a significant reduction in each cuttings (Figures 2 to 7). In fact, the reduction in these parameters with increasing irrigation interval is due to the lack of available water in the bed of cuttings. The results of present study is corresponding to results of Tavakoh et al (2011). Abedi and Asad Kazemi (2006) and Taylor and Halfacre (1986) that rooting index decreased with increasing of irrigation interval. With increasing hydrogel rates from zero up to 0.3%, rooting indices shoved a significant increase and reached its maximum value in the 0.3% hydrogel concentration (Figures 2 to 7). The reasons of increasing of rooting indices due to applying hydrogels up to 0.3% could be attributed to potentially high moisture absorption of hydrogel and storage of water in its network and due to increasing of available water 2 times versus control (Figure 1). With increasing of hydrogels up to 0.6%, the percentage of rooting and fresh and dry weight of cuttings decreased significantly. It appears that the reason for (his decline is that with the large amounts of hydrogel, the water amount in the rooting media of cuttings too (2.75 times compared to no use of hydrogels. Figure 1) increases. This increase is primarily a result of reduced air-filled pore space for cuttings media because of hydrogel swelling by water , Second, excessive moisture can cause the slime of rooting media and resulting of decrease of physiological and metabolic processes of root. These results are compatible with the results of Assareh et.al (2007), Meghani et.al (2009), Farokhzad et.al (2009) and Huttermann et al. (1999). Based on the mean comparison results of interaction between irrigation interval and hydrogel rates at each irrigation interval (Figures 2 to 7), it was found that with the increasing use of hydrogels up to 0.3%, the measured rooting's cuttings indices increased and the maximum value was related to 2 days irrigation interval. The reason of increasing of these indices in low irrigation interval (2 days compared with the control and 1 day) could be (hat the addition of hydrogel to media culture of cuttings could act like a storage water tank during the dry period and increased rapidly the moisture retention period of cuttings media and wetting and redistribution of water in the rooting zone of cuttings after irrigation. The results of this study is coincide with results of Jandagheyan et.al. (2001) about rooting of Phylodendron scandens and Pelargonium hortorum, Ghascnri and Khoshkhoe (2007) of Chrysanthemum morifoliumramat, Gehring and Lewis (1980) of Zinnia elegansand and Callendula officinalis. El-Hady and Warns (2006) of greenhouse cucumbers and Woodhouse and Johnson (1991) of Cupressus arizonica that the improved rooting index quantities derived from the interaction of the hydrogel and irrigation interval.
According to the present results can be stated that the use of hydrogels based on rates of 0.3 and 0.6%, the amount of available water increased 2 to 2.75 times respectively. The independently hydrogels usage as much as 0.3% increased rooting of Nerium oleander cuttings and improved root morphological characteristics, while irrigation interval alone has had a negative effect on rooting of cuttings of this plant. Interaction between the hydrogel and irrigation interval in the presence of 0.15, 0.3 and 0.6% hydrogel and 2 days irrigation interval improved rooting and root cuttings of Nerium oleander and morphological characteristics compared to the control treatment. But the highest rooting percentage, root fresh and dry weight and length and diameter of roots were observed in the 0.3% hydrogel and 2 days irrigation interval. According to these results, applying of 0.3% Tarawal hydrogel with 2 days irrigation interval can be suggested for optimum rooting of cuttings of Nerium oleander plant.
This work has been funded by Islamic Azad University, Yadegar-e-Imam Khomeini (RAH) Branch.
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Received 25 April 2014
Received in revised form 8 May 2014
Accepted 20May 2014
Available online 16 August 2014
(1) Kamran Parvanak and (2) Hadi Chamheidar
(1) Department of Soil Science, Yadegar-e--Imam Khomeini (RAH) Branch, Islamic Azad University, Tehran, Iran.
(2) Department of Soil Science, Shoushtar branch, Islamic Azad University, Shoushtar, Iran
Corresponding Author: Kamran Parvanak, Department of Soil Science, Yadegar-e--Imam Khomeini(RAH) Branch, Islamic Azad University, Tehran, Iran.
Table 1: Data analysis and statistics of the measurement indices of Nerium oleander cuttings under the experimental treatments. Mean of square SOV Df Amount of Percentage of available rooted cuttings water (%) Hydrogel rate 3 21.015 ** 2704.572 ** Irrigation interval 3 43.905 ** 6040.466 ** Hydrogel rate * 9 4.250 ** 326.643 ** Irrigation interval Error 32 0.099 1.847 Mean of square SOV Dry weight Fresh Root of cuttings weight of length root (g) cuttings root (cm) (g) Hydrogel rate 3.490 ** 4.958 ** 10.474 ** Irrigation interval 18.849 ** 18.751 * 66.503 ** Hydrogel rate * 0.395 ** 0.480 ** 1.546 ** Irrigation interval Error 0.074 0.064 0.073 Mean of square SOV Root The diameter number of (cm) roots per cuttings Hydrogel rate 0.824 ** 4.500 ** Irrigation interval 3.694 ** 68.000 ** Hydrogel rate * 0.152 * 6.833 ** Irrigation interval Error 0.033 1.302 *,** Significant at P = 0.05 and P = 0.01 levels, respectively.
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|Author:||Parvanak, Kamran; Chamheidar, Hadi|
|Publication:||Advances in Environmental Biology|
|Date:||Jul 23, 2014|
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