Correlation Between Growth and Yield of Greengram in Drip Fertigation, Fermented Fish Waste, Fermented Egg Product Application under Aerobic Rice (Oryza sativa L.)-Greengram (Vigna radiata L.) Cropping System in Western Zone of Tamil Nadu

Pulses, which are the wholesome edible seeds of leguminous plants, are crucial component of the human diet. Blackgram (Vigna mungo L.), a kind of pulse, is a significant legume crop grown in tropical and subtropical areas of the world (Kannamreddy et al., 2021). Greengram typically records poor yield being cultivated under rice fallow/ mixed cropping/rainfed situation with improper irrigation and nutrient management. Among rice-based cropping systems, rice-pulse cropping system is one of the most important cropping systems. For rice fallow greengram crop, zero tillage is adopted. In zero tillage, soil is not disturbed and soil is opened only for placing the seed. Succeeding crop is sown without any preparatory cultivation in the stubbles of the previous crop. It minimizes the labour and fuel cost. Weeds are controlled by surface application of post-emergence herbicides. The previous crop residue increases the water infiltration and reduces evaporation of soil water.
       
Higher available N was found with 100 % RDF drip fertigation at 15-30 cm depth from the emitters. The concentration of available N distribution in upper soil (0-15 cm) was lower than that of 15-30 cm soil layer. Availability of K was more under 100% RDF at 0-15 cm soil layer from the emitters in rice.
       
The bio fermented products obtained from plant or animal sources contains several compounds and mixture of several things such as microorganisms, plant hormones, plant growth regulating rhizobacteria, enzymes and humic acid trace elements that increases water holding capacity, enhance metabolism, increases antioxidants and regulates plant growth and yield, when applied as foliar spray reduces the micro nutrient deficiencies (Mesquita et al., 2012). Fermented fish waste, one of the bio extract products has the capacity to replace chemical fertilizers.
       
The liquid nature of the product increases the availability of nutrients when it is applied through drip irrigation. Fermented fish waste (FFW) and fermented egg product (FEP) combined with organic fertilizers can be used as an effective substitute for foliar fertilizer because it is safer and it could help in producing more quality farm produce. Soil drenching or foliar application of fermented fish waste increases the uptake and reduces the leaching, supplying required nitrogen to the crop for the production of chlorophyll to maintain plant health, improves the metabolic and cellular activity of greengram (Priyanka et al., 2019). The addition of fermented fish waste may be considered as a novel liquid biofertilizer as it promotes growth, nitrogen fixation by increasing root nodulation, enriching the soil with trace elements and microbial community (Hepsibha and Geetha, 2017).
               
Consequently, considering the above facts, field research was carried out to study the effect of drip fertigation, Fermented fish, egg waste application on growth, yield attributes and yield of greengram under aerobic rice (Oryza sativa L.) - greengram (Vigna radiata L.) cropping system.

Details of the experimental site
 
A field experiment was laid out in Field No. B6 at Wetland farm, Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during 2019 and 2021 situated in Western Agro- Climatic Zone of Tamil Nadu at 11°N latitude, 77°E longitude and at an altitude of 426.7 m above MSL (mean sea level). The experiment was laid out in a Randomized complete block design with thirteen treatments and replicated thrice and experimental crop details given Table 1. Treatment details for Greengram were T₁ - Drip fertigation (DF) @ 75% Recommended Dose Fertilizer (RDF), 75% Pan Evaporation (PE) with Fermented Fish Waste (FFW) (2 times), T₂ - DF @ 75% RDF, 75% PE with Fermented Egg Product (FEP) (2 times), T₃ - DF @ 100% RDF, 75% PE with FFW (2 times), T₄ - DF @ 100% RDF, 75% PE with FEP (2 times), T₅ - DF @ 125% RDF, 75% PE with FFW (2 times), T₆ - DF @ 125% RDF, 75% PE with FEP (2 times), T₇ - DF @ 75% RDF, 100% PE with FFW (2 times), T₈ - DF @ 75% RDF, 100% PE with FEP (2 times), T₉ - DF @ 100% RDF, 100% PE with FFW (2 times), T₁₀ - DF @ 100% RDF, 100% PE with FEP (2 times), T₁₁ - DF @ 125% RDF, 100% PE with FFW (2 times), T₁₂ - DF @ 125% RDF, 100% PE with FEP (2 times), T₁₃ - Surface irrigation with 100% RDF.
 

       
Drip laterals of 16 mm OD (250-micron wall thickness) fixed in the sub mains with a lateral spacing of 120 cm. Laterals had emitting point spaced at 30 cm apart with a discharge rate of 4 lph. Flow of water from sub main to laterals were regulated with a control valve in order to regulate the irrigation and fertigation scheduling and the laterals were closed with end cap. Each plot comprised of three laterals for irrigating 12 rows of rice and nine rows of greengram plants. Before sowing of greengram, glyphosate (41% SL) was applied to the experimental field with concentration @ 10 ml litre^-1 water was applied. Pre-emergence application of pendimethalin @ 1 kg a.i. ha^-1 on 3 DAS followed by one hand weeding during the vegetative period was done, to keep the field weed free till the crop canopy has considerably covered the ground. Recommended dose of fertilizer (RDF) for aerobic rice (150:50:50 NPK kg ha^-1) and greengram (25:50:25 NPK kg ha^-1) crop was applied and were taken as 100% RDF. In greengram, 50% N and K₂O as basal and remaining as two equal top dressing on 20 and 40 DAS under Conventional method. The fertilizer sources for supplying N, P and K through drip irrigation were urea (46% N), mono ammonium phosphate (12% N, 61% P) and sulphate of potash (50% K), respectively. Each bed consisted of one lateral for irrigating four rows of crops. The required quantity of N, P₂O₅ and K₂O fertilizers as per the treatment were dissolved in water separately. For greengram, fertigation was done through fertigation tank twice in a week starting from 10 to 45 DAS, which was regulated by taps, provided near take-off point of the sub main. Fertigation was carried out in three consecutive steps viz., wetting the root zone before fertigation, fertigating the field with water and nutrients. The growth attribute such as plant height, Dry Matter Production, 50% flowering, LAI, Physiological parameters such as SPAD values and RGR were recorded. The details of drip fertigation schedule for split application of fertilizer were given in Table 2 and layout of drip fertigation was given Fig 1.
 

 

       
Correlation is a method for determining the relationship between two variables. The correlation coefficient formula enables the calculation of the connection  between two variables and the resulting number describes the accuracy of the expected and actual values. In this article, correlation was employed to identify the relations among grain yield (kg ha^-1), plant height (cm), number of branches plant^-1, number of pods plant^-1, DMP (kg ha^-1, leaf area index, number of seeds pod^-1, pod weight (g) and its length (cm).

Effect on growth characters
 
Different drip irrigation and fertigation treatments significantly influenced the growth characters of greengram during both the years of investigation and the data was given in the Table 3. Higher plants height, DMP, were observed in the summer 2020 and the kharif 2021 with drip fertigation @ 125% RDF, 100% PE with FFW (2 times), (T₁₁) (60.7 and 57.3 cm) and (4463 kg ha^-1 and 4169 kg ha^-1), respectively, at harvest stage (Srinivasan et al., 2019; Balaji et al., 2019; Kumar et al., 2020). Similarly, the days to 50% flowering varied from 30.3 to 39.6 and 31.0 to 39.3 days, during summer 2020 and kharif 2021respectively. Among treatments, DF @ 125% RDF, 100% PE with FEP (2 times) (T₁₂) took more days for 50 % flowering (39.6 and 39.3 days during both the years) over all the treatments. Among different levels of drip fertigation practices, DF @ 125% RDF, 100% PE with FFW (2 times) (T₁₁) registered significantly higher LAI of 3.75 during summer 2020; 3.96 during kharif 2021 at peak flowering stage.
 

       
Different levels of drip fertigation in greengram significantly influenced the Chlorophyll meter reading (SPAD value), Crop growth rate, relative growth rate (RGR) between 30 and 45 DAS and 40 DAS and harvest during summer 2020 and kharif 2021 (Table 4). Among the treatments, significantly more SPAD values (T₁₁) (43.2 and 45.3 during summer 2020 and 42.8 and 45.9 during kharif 2021 at 30 and 45 DAS, respectively) was observed under DF @ 125% RDF, 100% PE with FFW (2 times), similarly same treatment registered higher CGR 14.29 g m^-2 day^-1 during summer 2020 and 16.38 g m^-2 day^-1 during kharif 2021 at 45 DAS- harvest stage. Different levels of drip fertigation in greengram significantly influenced the relative growth rate (RGR) between 40 DAS and harvest during summer 2020 and kharif 2021. Among the treatments, significantly higher RGR was measured in treatments T₇ (DF @ 75% RDF, 100% PE with FEP, 2 times) and T₁₂ (DF @ 125% RDF, 100% PE with FEP, 2 times) during summer 2020 and T₁₀ (DF @ 100% RDF, 100% PE with FEP, 2 times) and T₁ (DF @ 75% RDF, 75% PE with FFW, 2 times) during kharif 2021 between 45 DAS and harvest stage, respectively than all other treatments.
 

       
The reason for increased CGR, RGR and Chlorophyll meter reading  among the treatments could be due to frequent fertigation with water soluble fertilizers which would have provided a well aerated condition at root zone with adequate soil moisture content leading to supply of sufficient concentration of nutrients that did not fluctuate between wet and dry extremes contributes to optimum growth. Similar results were validated with Badr et al., (2010).
 
Effect on yield attributes and yield
 
The yield attributes viz, Number of pods per plant, Number of seeds per pod, Number of seeds per plant, were significantly influenced by the different drip irrigation and fertigation levels are furnished in Table 5. Among treatments, DF @ 125% RDF, 100% PE with FFW (2 times) (T₁₁) produced increased number of pods (35.6 pant^-1 and 26.9 pant^-1), number of seeds per pod (7.6 pod^-1 and 11.4 pod^-1) and higher number of grains plant^-1 of 269 and 308 during summer 2020 and kharif 2021) over other treatments tested in the field investigation (Srinivasan et al., 2021; Srinivasan et al., 2022). There was no significant difference in 100 grain weight (g) due to different drip irrigation and fertigation levels.
 

       
It might be due lower soil moisture supply, availability of nutrients also low which leads to low photosynthetic accumulation and results the increased in chaffy grains. These results are in confirmation with the results of Sudhir et al., (2011).
       
The seed and haulm yield were significantly influenced by the treatments imposed in both the  years of experimentation (Table 6). Among the drip irrigation and fertigation levels, DF @ 125% RDF, 100 % PE with FFW (2 times) (T₁₁) recorded higher seed and haulm yield (1352 kg ha^-1 and 2512 kg ha^-1) during summer 2020 and (1291 kg ha^-1 and 2403 kg ha^-1) during kharif 2021, respectively. However, harvest index did not show any significant impact on harvest index of greengram which ranged from 0.31 to 0.36 during summer 2020 and 0.34 to 0.37 during kharif 2021. These results are in line with the findings of Jayakumar et al., (2014) and Ajaykumar et al., (2022a).
 

 
Correlation analysis
 
The correlation findings were listed in Table 7 of the research. The study’s results indicated that, at the 1% level of significance, every variable in the model was positively significant. This indicates that every variable would have an impact on the greengram’s grain yield. The correlation coefficients between the grain yield and the plant height (0.97), DMP (0.98), LAI (0.99), number of pods plant^-1 (0.97), number of seeds pod^-1 (0.94) and test weight (0.24) revealed that all the attributes were positively related, which strongly suggests that when these variables are increased, the greengram yield will keep increasing Similar results were observed by Ajaykumar et al., (2022b). 
 

 
System productivity
 
Higher system productivity was observed under the DF @ 125% RDF, 100% PE with FFW (T₁₁) in both 2019-20 and 2021 (23 and 23 kg ha^-1 day^-1 respectively) and this was closely followed by DF @ 125% RDF, 100% PE with FEP (T₁₂) (22 and 22 kg ha^-1 day^-1 respectively). The lowest system productivity was registered with DF @ 75% RDF, 75% PE with FEP (T₂) (15 and 15 kg ha^-1 day^-1) during both the years of study are presented in the Table 8 and 9. The higher system productivity recorded due to higher production of rice and greengram increased the rice equivalent yield that leads to higher system productivity. This is in conformation with the findings of Ramadass and Ramanathan (2017) and Ray et al., (2019).
 

 

Based on the results of both the season, it is concluded that the application of drip fertigation @ 125% RDF, 100% PE with FFW (2 times) (T₁₁) recorded higher growth characters (plant height, dry matter production), physiological parameters like LAI, SPAD values, 50% flowering, CGR, Yield attributes, yield and system productivity were better compared to other treatments. However, it was comparable with the DF @ 125% RDF, 100% PE with FEP (2 times) (T₁₂). Hence, this is considered to be a suitable agro-technique to the greengram growing farmers for  realizing better yield and good system productivity.

None.