An Evaluation Study on Yield Sustainability of Rice Fallow Blackgram (Vigna mungo) Through Frontline Demonstrations Approach

Pulses play a crucial role in ensuring food security while simultaneously enhancing soil properties through biological nitrogen fixation.The production of pulses had increased by 5% (Moong-12%, Gram -11%,Tur-9%, Urd-6% and Lentil-4%) during the period from 2015-16 to 2021-22 which impacted the livelihoods of more than five crore farming families in India. Even then the current output cannot meet the demand and India imports to meet the insufficiency. India contributing to 25% share to world’s but its share to total food grain production declined from 16% (1950) to 8% (2023). Therefore India imports pulses to meet the demand and this can be stabilised by area and production expansion. Among the pulses, blackgram (urdbean) crop attained phenomenal increase in acreage since 2017-18 (48 lakh ha). Ten states contribute to 93 per cent of blackgram production with major contribution by Madhya Pradesh (32% production) followed by Andhra Pradesh, Uttar Pradesh, Tamil Nadu, Rajasthan, Maharashtra, Jharkhand, Gujarat, West Bengal and Karnataka. (Annual report 2022-2023, DPD, Bhopal www.dpd.gov.in as on 20.02.2024)
       
Among pulses, blackgram (Vigna mungo) stands out as a significant crop, contributing 2.84 million tons of production in India and 2.77 lakh tons in Tamil Nadu during 2021-22. In Tamil Nadu, Cauvery Delta Zone (CDZ) takes lead in both area (3.1 lakh hectares) and production of pulses which are grown using residual moisture after Samba rice crop during Rabi season (December to January) contribute over 40% to state’s pulse production. However, yield of these rice fallow pulses remains suboptimal, varying from 300 - 500 kg/hectare, in contrast to the potential yield achievable under irrigated conditions. In CDZ of Tiruchirappalli district, cultivation of blackgram, within the wetland rice ecosystem follows traditional practices, either manually broadcasting seeds in standing rice fields 7 to 10 days before harvest or dibbling immediately after rice harvest. This low-cost approach focuses on sowing and seed expenses. Black gram grew as succeeding crop in non-puddled transplanted rice recorded more nodules (23.67) with yield increase (11.8%) above puddle method of tillage (Subrahmaniyan et al., 2023). The present research was conducted during 2021 aimed to evaluate blackgram for its yield attributes and technology gap analysis under residual soil moisture cultivation to reap greater financial returns utilizing high-yielding cultivars and scientific methods in contrast to local farmers’ practices.

The study evaluated 205 field demonstrations in 82 hectares conducted in seven blocks of Tiruchirappalli district-Andanallur, Lalgudi, Manikandam, Musiri, Thiruverumbur, Thuraiyur and Uppiliyapuram during 2018-19 to 2020-21 at Krishi Vigyan Kendra (KVK), Tiruchirappalli, Tamil Nadu. Various KVK interventions, including On-farm Trials (OFT), FLDs, Cluster FLDs and demonstrations from the National Food Security Mission (NFSM) seed hub, were implemented to enhance black gram production.
       
Data on yield qualities/parameters, including technology index, Pearson correlation coefficient and independent sample t-test, were analyzed in the research. Latest short-duration, drought-tolerant Yellow Mosaic Virus (YMV) resistant black gram varieties (VBN 6, ADT 6, KKM1 and VBN 8) were assessed through field trials and yield-maximizing technologies viz., seed rate optimization, seed drill sowing, seed treatment with biocontrol agents, crop booster TNAU pulse wonder applications and Integrated Pest and Disease Management practices were evaluated.

The performance of yield attributes of blackgram on yield was assessed using Pearson Correlation Analysis and Independent sample T-test by collecting data from 25 plant samples from demo and farmer plots in 2021. The yield attributes taken into account for this research are X1 - Germination %; X2 - Plant height in cm; X3 – No. of pods/plant; X4 - Pod length in cm; X5 –No.of seeds/pod; X6 - Pod filling %; X7 - Seed yield g/plant.
       
The Pearson correlation coefficient (r) is a descriptive statistic that lists the characteristics of a dataset and calculates a linear correlation. A value between -1 and 1 indicates the strength and direction of relationship between two quantitative continuous variables. In order to compare the means of two sample groups and to ascertain statistically significant difference between means of two sets of data, the Independent sample T-test is used.
       
Marlabeedu et al.  (2022) formulas on technology index were studied in order to evaluate and quantify the influence of demo plot yield against yield obtained through traditional farmers’ practices (control plot).
   
    
       
The scientists regularly visited the fields and monitored periodically and data on yield parameters were collected from farmers during harvest both in demo and control plots. The details on cost of production and net returns have been collected from farmers in the research area. Evaluation of yield attributes and technology gap on yield through demonstrations in blackgram was analyzed and results are presented below:

Performance of yield attributes of blackgram on yield
 
The study revealed that demo samples recorded higher germination (72%) than control plot (67.68%) with 6.4% increase in germination over the control variety (Table 1). Plant height, number of pods/plant, length of pods, number of seeds/pod, pod filling percentage and number of seed produced per plant were all consistently larger in the demo plot variety of blackgram than in control plot variety. These factors enhanced the average yield in demo plot as 8.57 q/ha compared to control 7.07 q/ha. Similar results were reported by Kamaleshwaran and Karthiga (2021).


       
The results of Pearson correlation analysis showed that following yield attributes had a direct positive influence on yield: germination percentage, pod number /plant, plant height, pod length, seed yield/plant were noteworthy at 1% level of significance on blackgram yield, while number of seeds/plant and pod filling percentage were discovered to be quite important at 5% of level of significance (Table 2).


 
When comparing yield of blackgram between demo and control plot sample populations, the independent sample t-test analysis showed that following factors were highly significant: germination percentage, plant’s height, number of pods/plant, pod length, number of seeds/plant, pod filling percentage and seed yield/plant (Table 3 and Fig 1). This discloses that new blackgram cultivars suitable for rice fallow conditions should possess higher germination percentage, a greater number of pods and seeds/plant to give high yield under limited resources.




 
Evaluation of blackgram technologies implemented under frontline demonstrations
 
Percentage increase in productivity
 
Blackgram demonstration plot and farmers plot yield are compared in order to calculate the impact yield and resulted in a yield increase of 38.90% over farmers’ plots as demo farmers fully adopted practices like YMV resistant varieties, foliar spraying of Diammonium Phosphate (DAP), TNAU pulse wonder and 1% urea and 1% Potassium chloride (KCl) spray which enhanced yield (Table 4). Highest yield of 8.86 q/ha was recorded in 2020-21 with the introduction of new YMV resistant short duration synchronised maturing blackgram variety VBN 8 over the established YMV resistant variety VBN 6 (7.79 q/ha). This was possible with frontline demonstration of latest scientific blackgram technologies in farmers’ field in a consistent way. Comparable results were published by Raj et al., (2013), Kumar and Wilson (2017), Umamageswari et al., (2019), Singh et al., (2023) and Amuthaselvi et al., (2023) in context of blackgram.


 
Technology index
 
Technology index was analysed by comparing the potential yield and demonstration yield of blackgram cultivars. It makes additional yield-maximizing technologies and high-yielding cultivars feasible for farmers to use in their farms. Higher is the feasibility when the technology index number is lower. The percentage-based technology index is impacted by the size of the technological divide. As values for the technology index increase, the lesser will be the rate of adoption of technologies in blackgram. The values for the technology index in demo plots ranged from -1.90 % to -12.09 % (average -5.32 % in Table 4). Lower values of the technology index were recorded mainly due to continuous monitoring by scientists of KVK through FLD implementation, motivation of farmers in adopting yield maximizing technologies through trainings, extension programmes, field visits in addition to technical advice and critical inputs provided by the State Department and favourable climate and/or lesser pest and disease infestations through YMV resistant varieties. In the same line, research findings revealed by Saikia et al., (2018) in blackgram and Bharti et al., (2024) in green gram.
 
Economics
 
The economic returns in the study depended mainly on farmers’ yield in demo and control plots, cost of inputs utilized, wage rates of labor and existing market price fluctuations.  Using, current input and output costs during the period of research, the economics  of demo plot practices relative to farmer plot practices was computed. Table 4 clearly depicts higher average net returns (Rs.67050/hectare) with average BCR 2.71 in demo plots compared to farmers plots (Rs.40100/ha)average BCR 2.07. Alike conclusions stated by Saravanakumar et al., (2020), Natarajan et al., (2024) and Lalit et al., (2015) in blackgram,  groundnut and greengram respectively.

The scientific study revealed clearly that an increase in yield of 38.90% was recorded by cultivating high yielding YMV resistant blackgram cultivars and adopting modern scientific technologies. A lower value of the technology index signifies the successful performance of yield-maximizing technologies in blackgram, fostering a positive relationship and confidence between farmers and extension officials. Additionally, yield attributes that directly impacted production included germination percentage, plant’s height, pod number/plant, pod’s length and per plant seed yield. These findings provided researchers with fresh insights into black gram cultivars suitable for rice fallow. In essence, the study underscores that in blackgram cultivation, the adoption of systematically implemented yield-maximizing technologies, coupled with high-yielding YMV-resistant varieties through field frontline demonstrations, can significantly enhance productivity per unit area with effective utilization of residual moisture in rice fallow conditions.

The authors extend acknowledgement to ICAR ATARI Zone X, Hyderabad for it’s funding in the implementation of the FLD programmes and seed hub centre under NFSM during the period of study and technical backstopping by Tamil Nadu Agricultural University, Coimbatore.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.

The authors assure that the research was carried out as per Research ethics and that there is no conflict of interest involved.