Agronomic performance and economic analysis of soybean (Glycine max) in relation to growth regulating substances in Punjab, India

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1 Legume Research, 38 (5) 2015: Print ISSN: / Online ISSN: AGRICULTURAL RESEARCH COMMUNICATION CENTRE Agronomic performance and economic analysis of soybean (Glycine max) in relation to growth regulating substances in Punjab, India Jagmeet Kaur, Hari Ram*, B S Gill and Jasdeep Kaur Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana , India. Received: Accepted: DOI: /lr.v38i ABSTRACT A field experiment was conducted at the Punjab Agricultural University, Ludhiana (36 56' N, 75 52' E and altitude 247 m), India during rainy seasons of 2006 to 2008 in split plot design. Experiment comprised of twelve treatment combinations with four plant growth regulators application (salicylic 50 mg/l, 200 mg/l, 500 mg/l and water spray) in main plot and three stages of application time (at flower initiation, pod initiation and flower + pod initiation) in sub plot, was replicated thrice. Pods per plant in 500 mg/l were significantly higher than ethrel, salicylic acid and water spray. Ethrel 200 mg/l recorded seed yield statistically on par with salicylic acid 50 mg/l but significantly higher than water spray and lower than cycocel 500 mg/l. Pods per plant with plant regulators application at flower + pod initiation were significantly higher than flower and pod initiation. Application of growth regulators at flower and pod initiation gave significantly higher seed yield than flower and pod alone in On pooled mean basis growth regulators at flower + pod initiation gave 4.9 and 7.7% higher than at flower initiation and pod initiation respectively. Key words: Agronomic performance, Cycocel, Ethrel, Salicylic acid, Soybean. INTRODUCTION Due to large scale cultivation of rice, the demand of water for irrigation has risen causing a serious imbalance in the availability and consumption of water in Punjab, Haryana and Western U.P. In Punjab, the over-exploitation of ground water led to fall in the water table at 65 cm per year. In 66% area of central Punjab, water table will go as deep as feet by Rice is a water-guzzling crop. To fulfill its additional water need, excessive pumping of underground (Hira et al, 2009) water leads to decline in water table. What is the water requirement for soybean? Soybean [Glycine max (L) Merrill] found to be an alternative crop to rice. At present soybean cannot compete with rice due to assured price and higher grain yield of rice. At the time of soybean pod initiation the photosynthates sometimes may not divert to the developing sinks but goes to the vegetative parts for their growth. There is need to give the signal of developing sinks to the plants so that the dry matter accumulated may go to the developing pods. The role of plant growth regulators is well established in improvement of morpho-physiological attributes of the crop plants. The plant growth regulators stimulate the plant vegetative growth thereby enhancing the yield potential of the crop plants. Some of the growth *Corresponding author s hr_saharan@yahoo.com. regulators like salicylic acid, ethrel and cycocel may play a big role to increase the seed yield of soybean. Growth regulators are known to enhance the source-sink relationship and stimulate the translocation of photo-assimilates thereby helping in effective pod formation, seed development and ultimately the productivity of soybean. Salicylic acid is an endogenous growth regulator of phenol nature, which participates in the regulation of physiological processes in plant, such as stomatal closure, ion uptake, inhibition of ethylene biosynthesis, transpiration and stress tolerance (Khan et al, 2003). Jaykumar et al (2008) reported that application of salicylic 125 mg/l increased the dry matter production in black gram. Khan et al (2003) reported that application of salicylic acid enhanced the photosynthetic rate, stomatal conductance and transpiration rate in soybean. Ethylene released from Ethrel could possibly be utilized for promoting pod growth as Abbas (1991) has shown that early development is related to higher ethylene levels, thus decreasing flowering and pod shedding and thereby reducing abscission and improving better pod set. Furthermore, it has been reported that salicylic acid applications increase carbon dioxide (CO 2 ) assimilation and photosynthetic rate, thus increasing dry matter (Szepesi et al, 2005). Agricultural

2 604 LEGUME RESEARCH application of bio-regulator is becoming a useful practice that has improved the yield of soybean which can help to diversify rice in Indogangetic plains. Keeping all this in mind, the studies were conducted to assess the effect of growth regulators on agronomic performance and economic analysis of plant growth regulators on soybean. MATERIALS AND METHODS A field experiment was conducted at the Punjab Agricultural University, Ludhiana (36 56' N, 75 52' E and altitude 247 m), India during rainy seasons of 2006, 2007 and It was comprised of twelve treatment combinations with four plant growth regulators application (salicylic 50 mg/l, 200 mg/l, 500 mg/l and water spray) in main plot and three stages of application time (at flower initiation, pod initiation and flower + pod initiation), which were replicated three times. The soil of the experimental field was loamy sand, low in organic carbon (0.27%) and medium in available phosphorus (18.3 kg/ha) and potassium (230 kg/ha). During the whole cropping season, the rainfall of 482.3, and mm was received during 2006, 2007 and 2008, respectively. The crop received three, four and two irrigations in 2006, 2007 and 2008, respectively depending upon the rainfall. The crop (variety SL 525) was raised using nutrient 30 kg N and 60 kg P 2 O 5 per hectare at the time of sowing in the form of 50 kg Urea and 130 kg DAP. Pendimethalin (Stomp 30 EC) 0.45 kg/ha was applied using 500 litres of water on the same day followed by one hoeing (four weeks after sowing) in all the years of the study to control weeds. Total chlorophyll content was determined at 90 days after sowing. Five plants were selected at 90 days after sowing (DAS) from the plot which were sun dried and then the samples were dried in an oven for two days at 60±5 0 C temperature, anddry matter accumulation per plant was calculated. The data on plant height and pods per plant were collected from randomly selected five plants per plot at the time of harvest. Twenty pods per plot were selected to record data on number of grains per pod. From the total produce of each plot, 100 grains were counted and weighed to express seed index. The crop was harvested when the pods were matured; the bundles were sun dried for few days and then threshed manually. The data on biological and grain yield were collected at the time of harvest. The harvest index was calculated by dividing grain yield and biological yield. The economics was calculated using prevailing prices of inputs and output. The data were subjected to analysis in split design using standard procedures of ANOVA at 5% level of significance using IRRISTAT version 92 (IRRI, 1992). RESULTS AND DISCUSSION Growth characters: The dry matter accumulation by soybean plants was significantly influenced by all the treatments in all the years (Table 1). Cycocel 500 mg/l recorded the highest dry matter accumulation which was significantly higher than all the treatments in 2006, 2007 and on mean basis. But in 2008, it was statistically on par with ethrel 200 g/l. It might be due to higher photosynthetic efficiency in this treatment which accumulated higher dry matter.growth regulators application was significantly influenced by the time of application of growth regulators. The highest dry matter accumulation was recorded in flower + pod initiation time which was significantly higher than pod initiation alone but on par with flower initiation. The chlorophyll content recorded at 90 DAS was recorded to be the highest in cycocel 500 mg/l which was statistically on par with Ethrel 200 mg/l except in 2008 but was significantly higher than salicylic acid 50 mg/l (Table 1). Salicylic acid could not increase the chlorophyll content as compared to control (water spray). However, Shi et al (2006) indicated that foliar 1.00 mm salicylic acid increased the chlorophyll content of cucumber seedlings grown under heat stress. Devi et al (2011) recorded significantly higher chlorophyll content in soybean leaves with application of cycocel 500 mg/l. In 2006 and 2008 application of growth regulators at flower initiation and flower + pod initiation were statistically on par with each other for total chlorophyll content recorded at 90 days after sowing. It is suggested that total chlorophyll increased with application of growth regulators at flower initiation. Devi et al (2011) also recorded significantly higher chlorophyll content with application of cycocel 500 mg/l at flower initiation than at pod initiation. The highest height of the plant was recorded in water spray which was statistically on par with salicylic acid but statistically on par with ethrel in 2006 and 2007 (Table 1). But in 2008 and on mean basis plant height was the highest in salicylic acid, in 2008, it was significantly higher than all other growth regulators but on the basis of pooled mean it was significantly higher than water spray but statistically on par with ethrel and cycocel. Cycocel acts as an anti-gibberellin dwarfing agent, and its foliar application may induce deficiency of gibberellins in the plant and reduce the growth by blocking and conversion of geranyl pyrophosphate to coponyl pyrophosphate which is the first step of gibberellin synthesis (Moore, 1980). Stage of application of growth regulators were not significantly influence the plant height except in 2008 in which growth regulator application during flower initiation recorded the tall plants which was significantly higher when applied at pod initiation and flower + pod initiation stages. The more number of branches per plant were recorded in

3 Vol. 38 Issue 5, TABLE 1: Effect of growth regulators on dry matter accumulation (DMA), chlorophyll content, plant height and number of branches/plant of soybean. mg/l which gave significantly higher branches per plant than water spray, ethrel and salicylic acid application except in 2008 in which it was it was statistically on par with on par with 200 mg/l (Table 1). It might be due to suppressing effect of cycocel and ethrel on apical dominance of the soybean plants. Stage of application of growth regulators significantly influence the branches per plant except in 2007 in which it was non-significant. The number of branches per plant in plant regulators application at flower + pod initiation stages was the highest which was significantly higher than application time at flower initiation and pod initiation alone. The stem girth was not significantly influenced by any of the growth regulator in 2006 and 2007 (Table 2). But in 2008 the highest stem girth was recorded in cycocel 500 mg/l which was significantly higher than all other growth regulators. On the basis of pooled mean stem girth in cycocel 500 mg/l was only significantly higher than salicylic acid 50 mg/l and water but statistically on par with ethrel 200 mg/l. Application of growth regulators at pod initiation or at flower + pod initiation gave significantly higher stem girth than applied at flower initiation only in 2007 and 2008 and on pooled mean basis but in 2006 the effect was nonsignificant. Yield attributes and yield: All the growth regulators application recorded significantly more number of pods per plant than recorded in water spray (Table 2). The more number pods per plant was recorded in 500 mg/l which was significantly higher than ethrel, salicylic acid and water spray except in 2007 in which pods plant were statistically on par with salicylic acid but significantly higher than water and ethrel and water spray. Singh and Kaur (1981) reported that salicylic acid application on mungbean significantly increased the pods per plant and its yield. Salicylic acid application increased the number of flowers, pods/plant and seed yield of soybean (Gutierrez-Coronado et al, 1998). Cycocel has been used to check the abscission of flower and modify the crop canopy for improving the yield attributes in soybean (Gutierrez-Coronado et al, 1998). Ethrel has been reported to improve productivity of pulse crops like cowpea, pigeonpea, mungbean and soybean by increasing the number of pods, seed weight and seed yield (Bora and Bahra, 1989). Ethylene released from Ethrel could possibly be utilized for promoting pod growth as Abbas (1991) and Grewal et al (1993) have shown that early development is related to higher ethylene levels, thus decreasing flowering and pod shedding and thereby reducing abscission and improving better pod set. Application time significantly influenced the number of pods per plant. The highest number of pods per plant was recorded in plant regulators application

4 TABLE 3: Effect of growth regulators on seed yield, cost of cultivation, net returns and B:C (benefit: cost ratio) of soybean. TABLE 2: Effect of growth regulators on stem girth, number of pods/plant, seed index and straw yield of soybean. 606 LEGUME RESEARCH

5 Vol. 38 Issue 5, at flower + pod initiation which was significantly higher than flower and pod initiation in 2006 and on pooled mean basis. But in 2007 it was statistically on par with flower initiation and on par with pod initiation in The seed index was significantly influenced by plant regulators application except in 2007 (Table 2). In 2006, 2008 and on pooled mean basis the highest seed index was recorded in cycocel which was significantly higher than water spray but statistically on par with rest of the regulators in In 2008, it was significantly higher than all the rest of the treatments. On the basis of mean, 500 mg/l application was statistically on par with salicylic acid but significantly higher than ethrel and water spray. Application time could not influence the seed index. The increase in seeds/ pod and seed index with growth retardant treatments might be due to better translocation of photosynthates by shortening the plant height. Straw yield was significantly influenced by all the treatments in all the years (Table 2). Application of 500 mg/l gave significantly higher straw yield than all the treatments which recorded 5.1, 5.9 and 22% higher straw yield than recorded in salicylic acid, ethrel and water spray respectively. In 2006, the highest straw yield recorded in 500 mg/l was significantly higher than all other growth regulators. In 2007 and 2008 it was significantly higher than water spray but statistically on par with on par with salicylic acid and ethrel. But on the basis of pooled mean 500 mg/l recorded significantly higher straw yield than water spray and salicylic acid but statistically on par with mg/l. Application times of growth regulators could not influence straw yield significantly. However, application of growth regulators at flower initiation and pod initiation gave about 2.0% higher straw yield than recorded at flower or pod initiation alone. All the growth regulators gave significantly higher seed yield than water spray. Among them cycocel 500 mg/l is the number one (Table 3). It might be due to higher seed index in these treatments. The use of plant growth regulators have been found to greatly affect the reproductive development, partitioning coefficient, seed yield per plant and seed quality (Setia et al, 1996). The highest seed yield recorded in Cycocel 500 mg/l was significantly higher than all the treatments which recorded 11.2, 9.8 and 25.2% higher seed yield than recorded in salicylic acid, ethrel and water spray respectively. On the basis of mean the Ethrel 200 mg/l recorded seed yield statistically on par with salicylic acid 50 mg/l but significantly higher than water and lower than cycocel 500 mg/l. It might be due to more number of pods per plot recorded in these treatments. Jaykumar et al, (2008) reported higher seed yield of blackgram with application of salicylic acid (125 mg/l) due to increased pods per plant. Gutierrez-Coronado et al (1998) reported increased seed yield of soybean with salicylic acid application with increased seed index. Abbas (1991) also reported higher pod setting in pulse crop with cycocel. Other researchers (Grewal et al 1993) also reported higher grain yield in brassica, soybean and pea. The application time of growth regulators significantly influenced the seed yield of soybean. Application of growth regulators at flower + pod initiation gave significantly higher seed yield than flower and pod alone in But in other years and on pooled mean basis the application time effect was found to be non-significant. On pooled mean basis growth regulators application at flower + pod initiation stages gave 4.9 and 7.7% higher than at flower initiation and pod initiation respectively. Economic analysis : The cost of ethrel was more so the cost of cultivation was the highest in this treatment. Cost of application of growth regulators was the highest, when it was used in two stages of application i.e. at flower and pod initiation. Application of all growth regulators significantly increased the net returns as compared to water spray. It was due to increased grain yield in all the growth regulator treatments. The highest net returns and benefit cost ratio were recorded in cycocel 500 mg/l treatment which was significantly higher than all other treatments. However, net returns in ethrel 200 mg/l and salicylic acid 50 mg/l was almost similar in all the years and on pooled mean basis except in Interaction effects were found to be non-significant in all the characters. With increase in the grain yield of soybean crop, it will be possible to replace rice area in Indo- Gangetic plains for long-term sustainability. It can be concluded from three years of study that the potential of salicylic acid and ethrel growth regulators was not similar when compared to h cycocel but was higher than water spray control for soybean productivity. Application of 500 mg/l at flower and pod initiation can be used to enhance the grain yield, net returns and benefit cost ratio in soybean. ACKNOWLEDGEMENTS The study was supported by All India Coordinated Research Project on Soybean, Indian Council of Agricultural Research, New Delhi, India.

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