Foliar Application of Glycine Betaine and Potassium Silicate and Its Effect on Growth Performance of Jerusalem Artichoke Grown on Calcareous Soil Under Water Stress Conditions

Introduction

Jerusalem artichoke (Helianthus tuberosus L.) also called as sunchoke, and belongs to family Compositae (Asteraceae). Studies on nutritive value of Jerusalem artichoke tubers have revealed that they contain many important components( Praznik et al., 1998). It is also a better source for inulin and oligofructose, which are types of fibers that act as potent prebiotics, or food for probiotics. Denoroy (1996) reported that inulin is a soluble fiber that balances blood sugar. Moreover, soluble carbohydrates present beside inulin are its derivatives fructooligosaccharides, which are simple sugars (fructose and glucose) and saccharose. It was considered as a biomass crop for ethanol, also. The production of biogas from biomass is economically viable under certain conditions, and the possibility of increasing the cultivation of Jerusalem artichoke has increased the scientific interest about this crop (Gunnarson et al., 1985).

Stress caused by water  is  an  increasing  environmental  constraint  in agriculture,  cause several  damage  effects  on  plant  growth  and metabolic  processes,  including  water  relations,  photosynthetic assimilation, and nutrient uptake (Stone et al., 2001). The damage caused by water stress is one of the most important environmental stresses that cause heavy loss to the agriculture worldwide (Kumar et al., 2012). Water is essential and the plants should receive at least 1 inch per week to produce better tuber growth. The researchers indicated that vegetables are more sensitive to water stress compared to other crops. Flowering of Jerusalem artichoke begins in August and when the plants begin to brown in September, it’s time to harvest its tubers. The main problem that the agricultural production faces is the shortage of irrigation water. Under these conditions, crop water use efficiency, crop water content are seriously affected, leading to low net photosynthetic rate, growth decline, and storage root yield lack (Van Heeden and Laurie, 2008; Yooyongwech et al., 2016). Therefore, an effective technique and agricultural practices are required urgently   to save water for expansion of agricultural area and other purposes.

One  of  the  approaches  to reduce  the  negative  effects  of  water  deficiency  is  the  foliar application  by  potassium  silicate  which  aimed  to  improve  growth  and increase productivity under water stress (Kamal, 2013). Potassium silicate promotes the vegetative growth, yield components and mineral nutrient concentrations such as nitrogen, phosphorus and potassium elements in potato crop (Salim et al., 2014). Potassium is very important for both the basic physiological functions of plants, such as the formation of sugars and starch, proteins synthesis, cell division, growth and fruit formation. Potassium, also, affects the synthesis, conversion and storage of carbohydrates as well as the quality of potato tubers (Ebert, 2009; Dkhil et al., 2011).

Glycinebetaine(GB) is a quaternary ammonium compound which found naturally in a wide variety of plants, animals and microorganisms. The accumulation of GB is induced and synthesized in the chloroplasts of higher plants under variety of abiotic stress, such as high salt, water stress and cold (Jagendorf and Takabe,2001;Rontein et al.,2002), and the exogenous GB could enhance the resistance ability to water stress (Mahouachi et al.,2012). Glycinebetaine affords osmoprotection for plants and protects cell components from harsh conditions by functioning as a molecular chaperone (Sakamoto and Murata, 2002). Application an exogenous of GB improves the growth and survival of a wide variety of plants under several of abiotic stress conditions (Ashraf and Foolad 2007; Hoque et al., 2007; Park et al., 2006 and Chen and Murata, 2008). On the other hand, the antitranspirants reduces the water decrease during vegetative growth period and before or after fruits harvesting (Abd El Aal et al., 2008).

This study aims to assess the effect of foliar spraying with potassium silicate, glycine betain as two different antitranspirants and irrigation water stress on growth, yield and tubers' quality of Jerusalem artichoke crop and to determine the actual ET for Jerusalem artichoke plants.

Materials and methods

Field experiments:

Two field experiments were conducted during two successive summer seasons of 2017 and 2018 in the soil salinity lab. Res. Alexandria, Agricultural Research Center. Jerusalem artichoke plant (Helianthus tuberosus L.) cultivar Fuseau was used in this investigation. Planting tubers was done on April, 10^th and 9^th during growing seasons, respectively. Tuber seeds were planted at 60 cm apart on one side of the ridges within rows of 60 cm width and 4 m length. The physical and chemical properties of the experimental soil used were done and shown in Table (1), which had been determined according to Black (1965).

Table (1). Some physical and chemical properties of the experimental soil (average values of both seasons)

Experimental design and treatments

The experimental design used was a split-plot design with three replicates. Three irrigations levels 50%, 75% and 100% of crop evapotranspiration (ET_c) were assigned to main plots. The sub plots were devoted to four foliar applications included sprayed with distilled water as control, liquid potassium silicate (K₂SiO₃) 10 % K₂O and 25% SiO₂ and potassium silicate at rate of 5 cm³/l, glycin betain [(Carboxymethyl) trimethyl ammonium inner salt,( C₅H₁₁NO_2, MW: 117.146 g/mole) at 200 mg/l and their combination i.e., potassium silicate (P.S.) x  glycine betain (G.B.) foliar together. Foliar applied was done twice at 60 and 90 days after planting. Tween-20 (0.1%) was used as a wetting agent for each treatment. Each experimental sub plot consisted of two rows. The irrigation treatments started after 20 days of transplanting. During the first 20 days (initial stage), the Jerusalem artichoke plants were irrigated according to the calculated irrigation requirements, while in other stages (development, mid, and end) the plants irrigated by 100, 75 or 50% of water requirements using drip irrigation method. The following fertilizers were added to the soil at preparation before planting: 20 m³ organicmanure/fed. plus calcium super phosphate fertilizer (15.5% P₂O₅) was base dressed during soil preparations as recommended (150 kg ∕ fed.).  Nitrogen fertilizer was added in the form ammonium nitrate (33.5% N) at the rate of 300 kg ∕ fed. at three equal doses ; after four, eight  and twelve weeks from planting. Potassium sulphate (48% K₂O) was applied at rate of 90 kg ∕ fed. in two equal doses eight and twelve weeks after planting. During the growing seasons, all other recommended agro-managements such as disease pests and weed control were performed whenever they appeared to be necessary.

The crop evapotranspiration (ET_c) was determined by using CROPWAT 8.0 a computer program and according to Penman-Montieth equation (Allen et al., 1998). Meteorological data (2017 and 2018) were obtained online from Weather Station (latitude of 31°11′02″ N, longitude of 29°56′54″ E and altitudeof-2 m) in Alexandria-Nouzha Airport, Egypt at 4.5 km from experimental site location (Table 2).

Table(2). Average monthly maximum and minimum temperatures(^oC), relative   humidity (RH%) and wind speed (km/h) in the experimental location during 2017 and 2018 growing seasons

 Calculation of irrigation water requirements (IR)

Based on the climate data in Table (2), the ET_c values for Jerusalem artichoke were calculated in Table (3). The Crop water consumptive use (CU) is the amount of water equal to what is lost by plant while irrigation requirement (IR) depends on Cu, irrigation method and leaching fraction.  Both Cu and IR estimation is derived from crop evapotranspiration (ET_c) which can be calculated by the following equation:

   ET_C = K_C. ET₀

Where; K_C is the crop coefficient.  Crop coefficients values used for Jerusalem artichoke were 0.35, 0.60, 1.00, 0.35 for growth stages initial, development, mid, and end, respectivelyas suggested by(Baldini et al., 2011). It is the ratio of the crop ET_c to the ET₀ (Pereira et al., 2015). The K_c coefficient serves as an aggregation of the physical and physiological differences between crops. The daily reference evapotranspiration (ET_o) was estimated using Penman–Monteith’s modified equation (Allen et al., 1998). The ET_C and is expressed by the rate of mm/day. The data in Table (3) show the actual evapotranspiration, consumptive water use and irrigation water applied at different water stress during the seasons of 2017 and 2018.

Table (3). Average values of reference evapotranspiration (ET_O, mm / day), actual evapotranspiration (ET_C, mm), and crop coefficient (k_C) at plant growth during of 2017 and 2018 seasons

Calculation of water use efficiency

In the drip irrigation treatments, daily consumptive use (CU) of water was worked out based on the crop ET and at the end of the season the seasonal consumptive use of water was calculated and expressed in mm. Crop water use efficiency (CWUE) was calculated using the equation CWUE = Y / CU); where Y equals to the marketable tuber yield (kg/fed.), CU equals to the seasonal actual evapotranspiration ET_C (as unit m³/fed.). Irrigation water use efficiency (IWUE) was estimated using the formula (IWUE = Y / IR) according to Bozkurt et al., (2009), whereas, IR irrigation requirement equals to the seasonal water applied to the field (m³/fed.) and calculated according to the equation: IR=CU/ [Ea*(1-LF)], where the application efficiency (Ea) for drip irrigation equal 0.85 and the leaching fraction (LF) was considered as 0.10 of water requirement.  

Data recorded:

1. Vegetative growth characters :

A sample of three plants from each experimental plot was taken, randomly, at flower initiation stage (150 days after planting) to estimate plant height (cm), number of main stems, plant fresh weight (kg) and plant dry matter percentage.

1. Total tuber yield

Each plant in each experimental unit was taken at harvest time i.e. 180 days after planting to yield measure, number of tubers per plant, average tuber fresh weight (g/plant), total yield per plant( kg/plant) and total tubers' yield (ton / fed.).

1. Tuber’s quality and mineral content:

Ten tubers per treatment were token randomly, to determine tuber dry matter percentage calculated by drying 100 g of fresh sliced tubers in an electric air – drying oven at 70 °C till constant weight. Inulin content was determined in tubers according to the method of Winton and Winton (1958). Total carbohydrate was determined colorimetrically as gram of glucose /100g dry weight of tubers roots according the methods described by James (1995). In the digested dry matter of tubers nitrogen was determined according to the methods described by Pregl (1945) using micro-kjeldahl apparatus. Meanwhile, phosphorus was determined colorimetrically according to Murphy and Riley (1962). Potassium was determined against a standard using air propane flame photometer according to Chapman and Pratt (1961).

Statistical analysis:

Collected data from the experiments were statistically analyzed, using the analysis of variance method. Comparisons among the means of different treatments were done, using least significant differences (L.S.D) test procedure at p ≤ 0.05 level of probability, as illustrated by Snedecor and Cochran (1980) using Co-Stat software program (2004).

Results and Discussion

1-  vegetative growth parameters

The results relevant to this research will be presented and dissection as follows:     

1. The main effect of irrigation levels

Obtained results in Table (4) exhibit clearly that all the studied vegetative growth parameters i.e., plant height, number of main stems per plant, fresh weight of plant were significantly (p≤0.05) affected by irrigation levels treatments during both seasons of the growth. In this respect, decreasing the irrigation levels from 100 % of crop evapotranspiration (ET_c) to 50% consistently and continuously; decreased all morphological parameters of plant. However, dry matter percentage of plant foliage did not significantly (p>0.05) affected by irrigation levels treatments during both seasons. Such increment in plant morphological parameters due to the reduction of irrigation levels may be due to the main role of irrigation water for increasing the availability and diffusion as well as the uptake of macro and micronutrients by plant, which affect, greatly, the plant growth. Also, the reduction in plant growth due to the deficiency of irrigation water might be due to the lack of water absorption by plant which in turn effect on the role of photosynthetic assimilation insufficient water condition. Moreover, deficit irrigation as a water stress condition eventually reduces plant growth, chlorophyll content, water potential and transpiration rate as well as the free water in plant tissue, leading to deleterious effect on photosynthetic rate, stomatal conductance and intercellular CO₂ (Mingchi et al., 2010). Similar results, more or less, were recorded by (Cooper, 1980; Sharma et al. 1984; Abo-El Magd et al. 2007; Abo-Sedera et al. 2004).

b. The main effect of four foliar application

The results of Table (4) demonstrate foliar application of glycine betain, potassium silicate and interaction of them that exerted significant (p≤0.05) effects on vegetative growth characteristics of Jerusalem artichoke plants except for plant dry matter percentage. It is clear that vegetative growth characteristics, increased significantly i.e.,  plant height (cm), number of main stems and plant and fresh weight (kg) were recorded when the growing plants sprayed with potassium silicate and the interaction of G.B. x P.S. compared with G.B. and  control treatments during both growing seasons. Salim et al. (2014) and Abd El-Gawad et al. (2017) reported that potassium has an effect on photosynthesis, which is positively affect the vegetative growth of potato plant. It could be taken place due to the role of potassium on plant nutrition, i.e. promotion of enzymes activity and enhancing the translocation of assimilates and protein synthesis. Also, Sangakkara et al. (2000) ascribed the increase in the vegetative growth of potato plants to the role of K in biochemical pathways in plants and it amplifies the photosynthetic rates, CO₂ assimilation and facilitates carbon movement. Marschner (2012) reported that Potassium is a significant nutrient for numeral of physiological function, counting regulation of water and gas exchange in plants, protein synthesis, enzyme activation, photosynthesis and carbohydrate translocation in plants. Pilon et al. (2013) found that leaf area of potato plants increased because of silicon application. Similarly, silicon application reflected an increase in the leaf area and haulm dry weight readings (Abd El-Gawad et al., 2017). The enhancement effect of silicon on the vegetative growth could be attributed to activating antioxidant defense system or through their protective effect on the photosynthetic pigments in salt stressed plant (Ashraf et al., 2010). Romero-Aranda and Cuartero (2006) found that treating tomato plants with potassium silicate (K₂SiO₃) as a source of silicon (2.5 mM); improved leaf fresh, weight, area and net photosynthesis rate as well as water storage within plant tissues. Furthermore, Abou-Baker et al . (2012) indicated that spraying faba bean plants with silicon at 300 ppm as potassium silicate; recorded the highest significant average values of plant height, root length, shoot and root dry weight.  In this respect, Soja et al., (1990), Mansour et al. (2001), Tawfik et al. (2003) and Abo-El Maged et al. (2007) recorded, more or less, similar results on Jerusalem artichoke.

The application of glycine betaine; produced the highest average values in the most of vegetative growth parameters during both season. However, this increment did not reach the level of statistical significant when compared with foliar application  of potassium silicate and interaction of them  on plant fresh weight in the first season and plant dry matter percentage both season of the study. In this content, Osman (2009) found that application of 1 mM glycine betaine increased flag leaf area of rice. In addition, Abbas et al. (2010) found also that foliar application of G.B. caused improvement in growth of two eggplant cultivars. The growth improvement could be taken place due to G.B. as enhance for photosynthetic rate and stomatal conductance. In the other words, glycine betaine was effective in stimulating plant growth compared to the control treatment.

Table(4). Average values of some vegetative growth characters as affected by irrigation levels and four foliar applications of glycine betaine, potassium silicate and their interactions on Jerusalem artichoke plant during 2017 and 2018 seasons

Values followed by the same letter (s) within column are not significantly different (P<0.05)

C. The effect of tested interaction

The given results of Table (4) indicate that the given interactions exerted significant effect (p ≤ 0.05) on plant height, No. of main stem / plant and plant fresh weight/plant. In general, foliar application of Jerusalem artichoke plants with potassium silicate of 5 cm³/l and G.B. x P.S., gave the best results for the characteristics of plant height, No. of main stem/plant and plant fresh weight/plant with 100% of crop evapotranspiration (ETC) of irrigation levels applied during in both seasons.  As mentioned -earlier, the characteristic of dry matter percentage was not affected by the two independent variables; this trait was not affected significantly (P> 0.05) by the interaction between these two variables.

2. Yield and yield components

The results outlined in Table (5) indicate that Jerusalem artichoketuber yield and its component characters were significantly affected (p ≤ 0.05) by the two studied independent variables (irrigation water levels and foliar spraying with potassium silicate, glycine betain and G.B x P.S) during both seasons.

a. The main effect of irrigation level

regarding to the irrigation levels as a main effect, the results of   Table (5) appeared that there is a clear positive relationship between increasing the irrigation levels and the total tuber yield and its components (number and weight of tuber /plant, average tuber weight as well as total yield/fed.) during the two seasons of the growth. In this respect, the highest average values were recorded for such characters were at 100% ET_C followed by75% ET_C, while the lowest average values were recorded at 50%ETc. Total yield per plant (kg) was the only character that affected significantly (p ≤ 0.05 by irrigations levels in the first season. On the other hand, the tuber dry matter percentage was not significantly affected during the two seasons. It is known that the total yield and its components were highly correlated with the vigorous of the vegetative growth. These results might be attributed to lack of water absorbed and inhibition of photosynthesis efficiency under insufficient water conditions (Abo- El Maged et al., 2007). Similar results, more or less, were obtained by Smittle et al, (1990) and Abd –El Aal (2011) on sweet potato.

b. The main effect of foliar application

With regard to the main effect of foliar applicants variable, the result of (Table 5) demonstrate that Jerusalem artichoke tuber yield trait and its component characters were significantly (p ≤ 0.05) affected with (glycine betain at 200mg/l, potassium silicate of 5 cm³/l and their interaction compared with control treatment during both seasons. In this respect, No. of tubers per plant, total yield per plant and total yield per fed. were affected significantly(p ≤ 0.05) owing to foliar application of potassium silicate 5cm³ / l and because the interaction G.B. x P.S. during both seasons. Average tuber fresh weight trait was affected significantly (p ≤ 0.05) by four foliar application treatments in the first season only. On the other hand, tuber dry matter percentage was not affected significantly by the four foliar application treatments during the two seasons. In this regard, spraying potassium silicate at 5cm³/l significantly (p ≤ 0.05) gave rise to the highest average values, followed by spraying with the interaction (G.B. x P.S.) then spraying glycine betain at 200 mg/l, and finally control treatment, which significantly (p ≤ 0.05); recorded the lowest average values for the three traits. Abd El-Baky et al. (2010) reported that sweet potato total yield per plant and total yield / feddan illustrate positively response to supplying the potassium. The promising effects of four foliar spraying applications with potassium silicate, glycine betain, interaction (G.B. x P.S.) and control treatment on Jerusalem artichoke increasing yield/fed., and its component characters might be attributed to its profound effects on enhancing vegetative growth traits (Table, 4) and the role of potassium as a macroelement in assimilation and translocation of plant synthetic assimilated molecules from the organs of synthesis to the storage organs (tubers). This result is consistent with the confirmed by Soja et al.( 1990), Mansour et al. (2001), Tawfik et al. (2003) and Abo-El Magde et al. (2007) in their study on Jerusalem artichokecrop.

Table (5). Average values of yield and its components of Jerusalem artichoke as affected by   irrigation levels and foliar application of glycine betaine, potassium silicate and their interaction treatments during 2017 and 2018 seasons

Values followed by the same letter (s) within column are not significantly different (P<0.05)

c. The effect of tested interaction

Regarding the effect of the interaction between the independent variable irrigation levels and the second one, i.e., foliar application treatments on the total yield and its components. The results of Table (5) reveal that most of the studied characters were significantly (p ≤ 0.05) affected. The significantly highest average values for number of tubers/plant, total yield /plant and total yield / fed. were recorded due to the treatments of water level 75% ET_C with spraying  potassium silicate 5cm³/l. With regard to average values of tuber fresh weight (g), the tabulated results appeared that, irrigation with water level of 75% ET_C with spraying potassium silicate 5 cm³/l significantly; gave rise to the highest average values during the first season. While the tubers dry matter percentage was not significantly affected during both seasons.  Similar trend, more or less, was reported by Abo-Sedera et al. (2004) on taro and Abo- El Maged et al. (2007) and El-Sharkawy and El-Zohiri (2007) on Jerusalem artichoke.

 3. Tubers′ quality traits

a. The main effect of irrigation level

As for the tested water irrigation levels, the results of Table (6) divulged that the tested tubers′ quality traits (N%, P%, K%, total carbohydrate% and inulin% tuber content) were significantly affected (p ≤ 0.05) with the different levels irrigation water during the both seasons. Such results in Table (6) illustrated that nitrogen, phosphorus andpotassium as well as inulin and total carbohydrate percentage in produced tuber were significantly (p ≤ 0.05) increased with increasing irrigation levels up to 100 % ETc compared with 70 or 50 % ETc during growing season. These findings could be attributed to increasing soil moisture of root zone, which leads to such increments in the concentration of macroelements. Increasing of nutrients solubility and their availability to be absorbed and uptaken by plant and in turn increase their accumulation in produced tubers.  The obtained results are, more or less, in agreement with those reported by El- sharkawy and El-Zohiri(2007) and Abo-El Maged et al.(2007) on Jerusalem artichoke and Abo-Sedera et al.(2004) and El-Zohiri and Abd Elal (2014) on taro.

1. The main  effect of foliar application

Results obtained in Table (6) indicate that the foliar applicants besides exhibited significant positive effects (p ≤ 0.05) on increasing the concentration of the estimated elements as N and K tubers contents during the two seasons. While, the phosphorus and inulin contents in Jerusalem artichoke tubers was not significantly (p > 0.05) affected during both seasons.  Carbohydrate tubers content was positively affected by the four foliar applicants in the first season only.  Generally, the maximum increments of nitrogen, phosphorus, potassium total carbohydrates and inulin percentage content were detected for the foliar application of potassium silicate at 5 cm³ /l and G.B. x P.S. foliar application during both seasons. However, this increment did not reach the level of statistical significant when compared with them except for phosphorus and inulin percentage contents during both season. Shaaban and Abou El-Nour (2014) reported that foliar fertilization of potassium silicate may be more beneficial for silica deposition in the required key points which keep very healthy hairy roots allowing better water, macro- and micronutrient absorption. In this regard, Bhattarai and Swarnima (2016) explained that sugar content in potato tubers increases with the addition of potassium element to a certain level, and then starts to decrease. Low doses of potassium convert starch into sugar and vice versa at high doses. Khan et al. (2010) pointed out that increasing the concentration of potassium element has a positive effect on increasing tubers content of both sugars and starch. The recorded results are similar, more or less, to those reported by Abo-El Maged et al.(2007) on Jerusalem artichoke and Sameh and Shama, (2019) on potato. Abd El-Baky et al. (2010), reported that total yield of sweet potato per plant and total yield per feddan declared a positive response to supply with potassium. The promising effects of four foliar spraying applications with potassium silicate, glycine betain, interaction G.B. x P.S. and control (without spraying) on Jerusalem artichoke increasing yield/fed and its component characters, and these finding might be attributed to its positive effects on enhancing vegetative growth traits (Table 5) and the role of potassium as a macroelement in assimilation and translocation of plant synthetic assimilated molecules from the organs of synthesis to the storage organs (tubers). This result is consistent with those of Soja et al., (1990); Mansour et al. (2001); Tawfik et al. (2003) and Abo-El Maged et al. (2007) in their study on Jerusalem artichokecrop.

C. The effect of the interactions

Results of Table (6) indicate the interaction between irrigation levels and foliar applications of glycine betaine, potassium silicate, G.B. x P.S. and control, had a significant (p ≤ 0.05) effect on tubers K content during both seasons. The remaining estimated elements N, P and carbohydrate contents in tubers were not significantly (p > 0.05) affected by this interaction during both seasons except inulin content during the first season only. Generally, the best results were achieved when irrigation water level was 75%ET_C with spraying of potassium silicate at 5 cm³/l, followed by irrigations water level at 100% ET_C, while the lowest average values were at irrigation water level of 50% ET_C. It could be indicated that spraying the growing Jerusalem artichoke plants with potassium silicate solution at the rate of  5 cm³/l significantly (p ≤ 0.05) alleviated the adverse effects of decreasing irrigation water levels through improving the vegetative growth characters; resulting in increases in total tubers yield, and tubers′ quality characteristic

Table (6). Average values of Jerusalem artichoke tubers chemicals components as affected by irrigation levels and foliar application of glycine betaine, potassium silicate and their interaction during 2017 and 2018 seasons

Values followed by the same letter (s) within column are not significantly different (P<0.05)

 4.  Water use efficiency

Irrigation water use efficiency is defined as marketable yield per unit of irrigation water applied of growing plants, and is expressed as kg / m³. Results of Table (7) express that the estimated 100% ET_c values were 998 and 965 mm in 2017 and 2018, respectively. The water consumptive use (CU) values were 4193 and 4056 m³ fed⁻¹ while the irrigation requirement (IR) were 5426 and 5249 m³ fed⁻¹;  during the two growth seasons of 2017 and 2018, respectively (the application efficiency for drip irrigation equal 85% and the leaching fraction was considered as 10% of water requirement).

Table (7). Consumptive water use efficiency (CWUE) and irrigation water use efficiency (IWUE) by Jerusalem artichoke plant at 2017 and 2018 seasons