Effects of benzyl aminopurine (BAP) on growth, yield and biochemical characteristics of summer

mungbean cultivars

Rawnak Ara Noor-E-Ferdous1*and Bikash C Sarker2 

1Bangladesh Stevia and Food Industries Limited, Dhaka-1216, Bangladesh 

2Department of Agricultural Chemistry, Hajee Mohammed Danesh Science and Technology University, Dinajpur-5200, Bangladesh

Article history: Received: 02.01.2021, Accepted: 16.02.2021, Published: Online: 28.02.2021 

*Corresponding author: rawnakara28@gmail.com 

www.isciencepub.com 

ABSTRACT 

A field experiment was conducted to study the effect of benzyl aminopurine (BAP) on growth, yield and biochemical characteristicsof three summer mungbean cultivars, cv. Binamoog-5, BARI mung 6 and Binamoog-8 along with four treatments viz., H1-control (without BAP), H2-50 ppm BAP, H3-100 ppm BAP and H4-150 ppm BAPapplied at 15, 30, 45 and 60 days after sowing (DAS). Data were recorded on plant height, number of leaves plant-1, leaf area plant-1, dry root weight, root volume, number of root nodule, seed yield, chlorophyll, carotenoid and proline contents. Plant height, number of leaves plant-1, leaf area plant-1 and seed yield were statistically different among the cultivars and also significantly influenced by the application of different concentrations of BAP. The highest plant height (68.59 cm), number of leaves plant-1 (10.89), leaf area plant-1 (1677.8 cm2) and seed yield (1.69 t ha-1) were obtained by applying 100 ppm BAP. The interaction effect of cultivars and different concentrations of BAPwere statistically significant on plant height, number of leaves plant-1, leaf area plant-1 and seed yield. The highest plant height (71.88 cm), number of leaves plant-1 (12.46), leaf area plant-1 (1863.26 cm2) and seed yield (1.87 t ha-1) were obtained in Binamoog-8 by spraying 100 ppm BAP. Chlorophyll, carotenoid and proline contents were significantly influenced by the application of different concentrations of BAP. The study infers that BAP enhanced growth and yield of summer mungbean cv. Binamoog-8, which might be an alternative eco-friendly management practices. 

Keywords: BAP, carotenoid, chlorophyll, growth, mungbean, proline, seed yield. 

To cite this article: Noor-E-Ferdous RA and Sarker BC. 2021. Effects of benzyl aminopurine (BAP) on growth, yield and biochemical characteristics of summer mungbean cultivars. Intl. J. Agric. Med. Plants. 2(1): 21-30.

INTRODUCTION 

Mungbean (Vignaradiata (L) Wilczek) is one of the most important pulse crops of global economic importance. Economically it is the most important crop of the Vigna group, being rich in quality protein, minerals and vitamins and is alsoused as animal fodder and greenmanure. It contains flavonoids havingantioxidant activities. It originated in the South and Southeast Asia and widely grown in Bangladesh, India, Pakistan, Mayannmar, Thailand,Philippinnes, China and Indonesia. Mungbean has special important as an accommodative crop with short growing period along with N2 fixation in soil (Noor-E-Ferdous et al. 2012). Plant growth regulators (PGRs) are being used as an aid to enhance yield of different crops (Noor-E-Ferdous et al. 2020, Noor et al. 2018, Hussain et al. 2018, Bakhsh et al. 2011, Sarker et al. 2009, Nickell 1982). PGR is either naturally or synthetic compounds that are applied directly to a target plant to alter its physiological processes or its structure to improve quality, increase yields, or facilitate harvesting control, undesirable vegetative growth of crop plants, enhancing fruiting bodies (Sarker et al. 2020). Similar PGRs are active in different stages of the same plant in different ways. An exogenous application of plant growth regulators affects the endogenous hormonal pattern of the plant, either by supplementation of sub-optimal levels or by interaction with their synthesis, translocation or inactivation of existing hormone levels. Plant hormones regulate physiological process and synthetic growth regulators may also stimulate growth and development of field crops thereby enhanced total dry mass and yield. (Sanjida et al. 2019, Cho et al. 2008, Chibu et al. 2000, Das and Das 1996). Application of 6-BAP found to increase plant height, number of leaves plant-1, natural product measure with resulting upgrade in seed yield in various plants (Sarker et al. 2020). The uses of growth substances such as 6-benzyl aminopurine (6-BAP), NAA, GA3 and some others at different concentrations increased aromatic rice grain production (Sarker et al. 2020). It is certain that endogenous and exogenous plant development controllers assume a vital job in adjusting and directing numerous physiological procedures in plants and these procedures are significantly affected by natural conditions. Although some exploration works were done and a few summer mungbean cultivars were released by Bangladesh Agricultural Research Institute (BARI) and Bangladesh Institute of Nuclear Agriculture (BINA), summer mungbean cultivars were given less attention and their yielding ability was not studied well by using plant growth regulators. Research on summer mungbean using BAP is limited in Bangladesh. Findings in using different PGRs for increasing summer mungbean yield in some countries certainly provide valuable information; those can't be prescribed without preliminary field trial in Bangladesh. Therefore, more researches are necessary to investigate the efficacy of BAP on summer mungbean production. Thus, the objective is to study the growth characteristics, -yield potentials and biochemical attributes of three selected summer mungbean cultivars in response to BAP.   

MATERIALS AND METHODS 

Experimental sites and treatments: A field study was conducted at the research field of the Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur, Bangladesh.  The research site was located in Northwest of Bangladesh, an agriculturally important region. It is between 25.13º N¢ latitude and 88.23º E¢ longitude and at an elevation of 34.5 m above the sea level. The experimental land belongs to the Himalayan Piedmont Plain, Agro-ecological Zone (AEZ-1) and Ranishankail soil series classified by FAO (1988). The experimental field was a medium high land having sandy loam soil with pH 5.60. The experiment using three summer mungbean cultivars was considered as factor A (V1-Binamoog-5, V2-BARI mung 6 and V3-Binamoog-8) while factor B were fourtreatments viz,. H1-control (without BAP), H2-50 ppm BAP, H3-100 ppm BAP and H4-150 ppm BAP. The experiment was laid out in Randomized Complete Block Design (RCBD) with 2 factors. Twelve combined treatments were V1H1, V1H2, V1H3, V1H4, V2H1, V2H2, V2H3, V2H4, V3H1, V3H2, V3H3 and V3H4, respectively for the purposes. Crop management practices like fertilizer, irrigation and pest management were done properly as and when necessary. Three irrigations were applied where the first pre-sowing irrigation was done at the time of lime application @ 1.0 t ha-1 and were mixed with soil before two week of seed sowing (Noor-E-Ferdous  2016) for better germination, second irrigation was done after weeding and thinning, and third irrigation was done at flowering stage. Specific concentration of BAPfor experimental treatments was prepared and applied in the form of foliar sprays at 25 and 45 DAS. 

Growth and yield contributing characters: Three plants were selected randomly from each plot and plant height was measured from base of the plant up to the tip of the main stem at 15, 30, 45 and 60 days after sowing (DAS). Leaves (trifoliate) were counted on each sampled plant at 15, 30, 45, 60 DAS and at mature stage. For root volume measures, three plants from each plot were collected carefully at 15, 30, 45, 60 DAS and at mature stage so that no root damage occurred. Root volume was measured by water displacing methods using 20 mL measuring cylinder followed by oven dried at 65oC for 72 hours. The average dry root weight was calculated. The number of nodules in the root of each collected plants were counted and noted at 30, 45, 60 DAS and at mature stage. Seeds obtained from each unit plot were sun-dried and weighed carefully. The pod was collected by handpicking when full maturity came turning brown to black in color. Seed weights of sample plants were added to the respective unit plot yield to record the final seed yield per plot. Seed yield was expressed as kg ha-1 after adjusting at 10% moisture level. 

Biochemical analysis: Fresh leaf samples from mungbean plants at the flowering stage were collected for chlorophyll estimation. Chlorophyll content of mungbean leaves was determined by following the method described by Arnon (1949).   

Chl-a=12.21 A663-2.81A646 (mg g-1 FW) 

Chl-b=20.13 A646-6.03A663 (mg g-1 FW) 

Total carotenoid = (1000A470 - 2.05×Chl-a - 114.8×Chl-b) / 245 (mg g-1 FW) by Porra (2002). 

Free proline content of leaves was estimated using the acid ninhydrin method described by Bates et al. (1973). Approximately 50 mg of fresh leaf sample (same leaf sample for chlorophyll estimation) at flowering stage was collected in a 2 mL Eppendorf tube and extract was prepared using 3% sulfosalicylic acid. The optical density of solutions (sample solutions and standard solution) was measured at 520 nm wavelength using UV-visible spectrophotometer with the help of standard curve using proline standard series solution. 

Statistical analyses: The obtained data on different parameters were statistically analyzed using the MSTAT-C program. The treatment means were compared by Least Significant Difference (LSD) followed by Duncan’s Multiple Range (DMRT) Test (Gomez and Gomez 1984). 

RESULTS AND DISCUSSION 

Plant height: The height of summer mungbean plants of different cultivars at different growth stages was markedly influenced by the application of BAP (Table 1). Result showed that significantly (P<0.05) highest plant height (10.28, 22.06, 42.4 and 67.93 cm) were observed in V3 (Binamoog-8) from 15 to 60 DAS with 15 days interval while the lowest plant height (9.62, 20.97, 40.54 and 63.60  cm) were observed  in V2 (BARI mung 6) at 15, 30, 45 and 60 DAS, respectively. The variation in plant height might be attributed to the varietal characters of mungbean. Plant height was significantly influenced by the application of different concentrations of BAP at all growth stages of mungbean (Table 1). The concentration of 100 ppm BAP produced the highest plant height (10.08, 24.04, 44.31 and 68.59 cm) at different DAS. The lowest plant heights (9.65, 18.91, 36.78 and 61.75 cm) were observed in control (H1) treatment in respective DAS. The interaction effect of varieties and different concentrations of BAP were statistically significant at different days after sowing (Table 1). The highest plant height (10.36, 24.97, 45.08, and 71.88 cm) was obtained in V3H3 (with Binamoog-8×100 ppm BAP) treatment at 15, 30, 45 and 60 DAS, respectively.  The lowest plant height (8.92, 18.24, 35.99 and 61.07 cm) was observed in V2H1 (BARI mung 6×with no BAP application) treatment at 15, 30, 45 and 60 DAS, respectively. From the above observation, it was found that the plant height was increased with the increasing doses of BAP along with Binamoog-8. Khanam (2016) reported that application of 6-BAP showed better performance on plant height of two rice cultivars studied at both vegetative and harvesting stages.   


Number of leaves plant-1: Number of leaves plant-1 differed significantly (P<0.05) among the varieties at different days after sowing (Table 2). Binamoog-8 (V3) had the highest number of leaves plant-1i.e., 4.11, 6.92, 8.52, 11.58 and 10.64 at 15, 30, 45, 60 and at mature stage, which were statistically different among other varieties and the lowest number of leaves plant-1 were 3.73, 5.28, 6.93, 8.19, and 7.42 from BARI mung 6(V2) cultivar (Table 2). Effect of BAP significantly influenced on number of leaves plant-1 at 30, 45, 60 DAS and mature stage. The highest number of leaves was found in 100 ppm BAP application (H3) treatment at 30, 45 and 60 DAS, respectively. But at the mature stage, the highest number of leaves was observed in 150 ppm BAP (H4) treatment. The lowest number of leaves was observed in control treatment. A significant variation was found with the interaction effect between varieties and different concentrations of BAP in respect of number of leaves plant-1 of mungbean at DAS (Table 2). The highest number of leaves plant-1 (4.65, 7.43, 9.13, 12.46 and 11.66) at 15, 30, 45, 60 DAS and mature stage was observed in V3H3 (Binamoog-8 × 100 ppm of BAP) treatment. The lowest number of leaves plant-1 (3.41) was observed in V1H3 (Binamoog-5 × 100 ppm of BAP) treatment at 15 DAS but the lowest number (5.01, 6.78, 7.66 and 6.98) was observed in V2H1 (BARI mung 6 × without BAP) treatment at 30, 45, 60 DAS and mature stages, respectively. Number of leaf plant-1 in BAP sprayed plants was significantly different from the controls and there was a trend that it was higher than the controls though contrasting result was also in aromatic rice plants revealed by Sarker et al. (2020). 



Leaf area plant-1: Effects of varieties was significant in leaf area plant-1 at 15, 30, 45, 60 DAS and at mature stage (Table 3). The highest leaf area plant-1 (35.56, 236.68, 887.31, 1689.6 and 1565.4 cm2) was observed in V3 (Binamoog-8) at 15, 30, 45, 60 DAS and mature stage, respectively. The lowest leaf area plant-1 (28.98, 225.43, 668.58, 1252.8 and 1099.6 cm2) was observed in V1 (BARI moog 5) treatment at 15, 30, 45, 60 DAS and mature stage, respectively. Leaf area plant-1was significantly influenced by the application of different concentrations of BAP at all growth stages of mungbean (Table 3). The treatment H4 (150 ppm BAP) produced the highest leaf area plant-1 (35.24 cm2) at 15 DAS but the highest leaf area plant-1 (247.87, 879.63, 1677.8 and 1551.7 cm2) was observed in H3 (100 ppm BAP) at 30, 45, 60 DAS and mature stage, respectively. The lowest leaf area plant-1 (29.53, 201.56, 689.78, 1367.4 and 1189.2 cm2) was found in H1 (control) treatment at 15, 30, 45, 60 DAS and mature stage, respectively. A significant variation was found on leaf area plant-1 at 15, 30, 45, 60 DAS and at mature stage by the interaction effect of varieties and different concentrations of BAP (Table 3).The highest leaf area plant-1 (40.11, 257.63, 1028.91, 1863.26 and 1734.82 cm2) was observed in V3H3 (Binamoog-8×100 ppm BAP) treatment and the lowest leaf area plant-1 (197.34, 592.64, 1027.35, 922.84 cm2) was obtained in V2H1 (BARI mung 6×without BAP) treatment  at 30, 45, 60 DAS and at mature stage, respectively except the lowest one (27.91 cm) was obtained in V2H3 (BARI mung 6×100 ppm BAP) at 15 DAS. GA3 induced higher leaf areas as reported in mungbean plant by Rahman et al. (2018), in rice plants (Liu et al. 2012), tomato plants (Khan et al. 2006) and summer mungbean plants (Noor-E-Ferdous et al. 2020). 


Dry root weight plant-1: Dry root weight plant-1 was recorded from 15 DAS to mature stage. Significant variation was observed on dry root weight plant-1 except 15 DAS and mature stage (Table 4). Maximum dry root weight (0.152, 0.497 and 1.15 g plant-1) was recorded in V3 (Binamoog-8) at 30, 45 and 60 DAS. The lowest dry root weight plant-1 (0.112, 0.373 and 1.018 g plant-1) was observed in V2 (BARI mung 6) at 30, 45 and 60 DAS, respectively. BAP treatment of H3 (100 ppm of BAP) showed the highest weight of dry root at all stages except 15 DAS and the lowest dry root weight was observed in control treatment except 15 DAS. Dry root weight showed significant difference among the interactions effect between varieties and different concentrations of BAP at 15 to 60 DAS and at mature stage (Table 4). Among the interaction effect, the highest dry root weight (0.02 g) was observed in V1HI treatment and similar result were observed in V2H2, V3H1 and V3H4 treatments and others treatments were 0.01 g. On the other hand, significantly highest dry weight of root was observed in V3H3 treatment while the lowest root weight was observed in V2H1 treatment in all the growth stages. Similar result was observed in root dry weight where root dry weight was increased with increasing GA3 concentration (Noor-E-Ferdous et al. 2020) and NAA concentration (Noor-E-Ferdous et al. 2012) in mungbean plant.

Number of root nodule plant-1: A significant difference in number of root nodule was also observed at all growth stages among the three cultivars of summer mungbean (Table 5). Results revealed that the number of root nodule was maximum in V3 (Binamoog-8) and minimum  number of root nodule was observed in V2 (BARI mungbeen 6) at 30 to 60 DAS and at mature stage. Number of nodule plant -1 differed significantly spraying with BAP at different days after sowing. The treatment H3 (100 ppm BAP) produced the highest number of root nodule at 30 to 60 DAS and at mature stage and the lowest number of nodule was observed in H1 (control) treatment. The interaction effect of varieties and different concentrations of BAP were statistically significant at different days after sowing (Table 5). The highest number of root nodule plant-1 was observed in V3H3 (Binamoog-8×100 ppm BAP) treatment and the lowest number was observed in V2H2 (BARI mung 6×BAP) treatment at 30 DAS to mature stage. The result was in agreement with that of foliar application of nutrients and growth regulators found to increase in the morpho-physiological parameters, number of root nodules plant-1 and dry weight of nodule in soybean by the foliar application of hormones and nutrients (Ketki and Thakare 2006, Noor-E-Ferdous et al. 2012, Raut et al. 2017). 


Root volume: The root volume was recorded from 15 to 60 DAS. Significant variation was observed in V3 (Binamoog-8) cultivar in respect of root volume at 30 to 45 DAS due to cultivar except 15 and 60 DAS (Table 6). Effect of different concentrations of BAP also significantly influenced on root volume at 15 to 60 DAS. The highest root volume was observed in H3 (100 ppm BAP) treatment at all growth stages. The lowest root volume was observed in H1 (0 ppm BAP) treatment at 15 to 60 DAS. The interaction effect of cultivar and different concentrations of BAP for root volume was significant at 15 to 45 DAS except 60 DAS (Table 6). Results revealed that the highest root volume was observed in V1H3 (Binamoog-5×100 ppm BAP) treatment and the lowest root volume was observed in V2H1 (BARI mung 6×without BAP) at 15 and 30 DAS. At 45 DAS, the highest root volume (7.01cm3) was found in V3H3 followed by V1H3 treatment. The V2H1 (BARI mung 6×without BAP) treatment showed the lowest root volume at 45 DAS. Finally, the interaction effect of cultivar and different concentrations of BAP on root volume at 60 DAS was non-significant effect (Table 6). Similarly, the present findings was in well agreement with Noor-E-Ferdous et al. (2012) regarding NAA  


sprayed summer mungbean plants that NAA induced higher root volume in mungbean plants resulted in absorption of more soil water and nutrients. 

Chlorophyll content: Chlorophyll-a content was observed non significant effect among the varieties and ranged from 1.39-1.46 mg g-1 (Table 7). Significant influence by the application of different concentrations of BAP on chlorophyll-a content in summer mungbean was recorded. The highest chlorophyll-a content (1.51 mg g-1) was found due to the application of 100 ppm BAP. The lowest chlorophyll-a content (1.34 mg g-1) was observed at control (H1) treatment. The interaction effect of cultivars and different concentrations of BAP was statistically significant on chlorophyll-a content (Table 7). The highest chlorophyll-a content (1.55 mg g-1) was obtained in V2H3 (BARI mung 6×100 ppm BAP) treatment and the lowest chlorophyll-a content (1.26 mg g-1) was observed in V2H1 (BARI mung 6×without BAP application) treatment. The chlorophyll-b content was non-significant effect among the varieties and ranged from 0.50-0.53 mg g-1. Chlorophyll-b content was significantly influenced by the application of different concentrations of BAP. The highest chlorophyll-b content (0.60 mg g-1) was obtained in H3 (100 ppm BAP) and while the lowest content (0.43 mg g-1) was obtained in H1 (without BAP) treatment. The interaction effect of varieties and different concentrations of BAP was statistically significant on chlorophyll-b content (Table 7). The highest chlorophyll-b content (0.61 mg g-1) was obtained in V3H3 (Binamoog-8 × 100 ppm BAP) and V1H3 (BARI moog 5×100 ppm BAP) treatment and while the lowest chlorophyll-b content (0.43 mg g-1) was observed in V2H1 (BARI mung 6×without BAP application) treatment. The present result was in agreement with Noor-E-Ferdous et al. (2012) where they found that GA3 provided the highest chlorophyll content in summer mungbean plant. 

Carotenoidcontent: Carotenoid content differed significantly among the varieties (Table 7). Binamoog-8 (V3) observed the highest carotenoid content (0.42 mg g-1) which was statistically different among other varieties. This variation might be due to the different physiological and morphological characteristics of the varieties. Carotenoid content was significantly influenced by the application of different concentrations of BAP (Table 7). The highest carotenoid content (0.4.8 mg g-1) was obtained in H3 (100 ppm BAP) and the lowest content (0.35 mg g-1) was obtained in H1 (without BAP) treatment. The interaction effect of varieties and different concentrations of BAP was statistically significant on carotenoidcontent. The highest carotenoid content (0.53 mg g-1) was obtained in V3H3 (Binamoog-8×100 ppm BAP) treatment. The lowest carotenoid content (0.32 mg g-1) was observed in V1H2 (Binamoog 5×50 ppm BAP) treatment.  

Prolinecontent: Proline content was non-significant among the varieties and ranged from 1.40-1.35 mg g-1 (Table 7). Proline content was significantly influenced by the application of different concentrations of BAP (Table 7). The highest proline content (1.47 mg g-1) was obtained in H4 (150 ppm BAP) and the lowest content (1.27 mg g-1) was obtained in H1 (without BAP) treatment. The interaction effect of varieties and different concentrations of BAP was statistically significant on proline. The highest proline content (1.54 mg g-1) was obtained in V3H4 (Binamoog-8×150 ppm BAP) treatment and the lowest proline content (1.26 mg g-1) was found in V2H1 (BARI mung 6×without BAP) treatment. Sarker et al. (2020) reported that the highest proline content (0.353 mg g-1 FW) was recorded in Chinigura rice with 20 ppm 6-BAP application. 

Seed yield: Seed yield differed significantly among the varieties (Table 7). Binamoog-8 (V3) observed the highest seed yield (1.44 t ha-1), which was statistically different among other varieties. This variation might be due to the different varietal characteristics of mungbean. The seed yield was significantly influenced by the application of different concentrations of BAP. The highest seed yield (1.69 t ha-1) was obtained in H3 (100 ppm BAP) and the lowest yield (1.19 t ha-1) was obtained in H1 (without BAP) treatment. The interaction effect of varieties and the different concentrations of BAP were statistically significant on seed yield (Table 7). The highest seed yield (1.87 t ha-1) was obtained in V3H3 (Binamoog-8×100 ppm BAP) followed by V1H3 (BARI moog 5×100 ppm BAP) treatment. The lowest seed yield (1.03 t ha-1) was observed in V2H1 (BARI mung 6×without BAP) treatment. Exogenous application of BAP significantly increased yield and yield components of aromatic rice (Roxy 2016, Sarker et al. 2020). 



CONCLUSION 

It is concluded that growth, yield and biochemical characteristics of summer mungbean cv. Binamoog-8 cultivar was increased exogenous foliar application of BAP @ 100 ppm. Most of the yield and yield contributing parameters quantitatively increased by the concentration of 100 ppm BAP on Binamoog-8 summer mungbean cultivar than that of Binamoog-5 and BARI Mung 6. In regard to all parameters, application of 100 ppm BAP on Binamoog-8 cultivar performed the best regarding the growth, yield and yield components. It is concluded that summer mungbean Binamoog-8 and Binamoog-5 showed better performance at 100 ppm and may be recommended for the farmers’ level to increase summer mungbean production for farm management practices. 

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