INTRODUCTION Black gram (Vigna mungo) is one of the highly valuable pulse crops concerning nutrition around the world that is grown in both seasons Kharif and Rabi. It is grown on approximately about 3 million hectares and the annual production of this crop is 1.5 to 1.9 million tonnes in India. We can grow this crop throughout the year because it is photo insensitive crop and also a self-pollinated crop. Moreover, it is a short-duration crop, easily suitable in any cropping system and has relative drought tolerance (Cheeran et al., 2017; Gandi et al., 2018). The yield of the black gram crop is adversely affected by the high temperature and drought (Baroowa and Gogoi 2015). It offers nutrition benefits to human beings and provides food security while the additional benefit is given to the soil concerning nitrogen for other crops (Khiangte and Siddique 2021). Humic acid promotes plant growth and yield by increasing nutrient intake and operating on different systems such as cellular respiration, photosynthesis, protein synthesis, and enzyme activities because it is a powerful adsorption and retention complex for inorganic plant nutrients (El-Saadony et al., 2021; Ozfidan-konakci et al., 2018). Zinc and boron both are essential micronutrients that play a wide role in the plant metabolic process in which Zn is the only element that includes in all the classes of an enzyme. Zinc is an element that is required for the biosynthesis of Auxin in the plant system therefore the deficiency of Zinc may show a reduction in auxin content in the plant consequently it alters the growth and development mediated by the interference in carbohydrate and nucleic acid metabolic process (Choudharyet al., 2020; Auld, 2001; Latef et al., 2017). Boron is another micronutrient that interferes in the translocation of sugar from the source to the sink (Farooq et al., 2012; Kihara et al., 2020). Therefore, to enhance the production of black gram, the present piece of work was considered for the research. MATERIALS AND METHODS The present piece of research work was planned and executed over the Research Farm of Agronomy, Lovely Professional University, in Kharif seasons of 2021-22. The experiment was laid out in a Randomized Block Design along with the combinations of ten treatments and one control. The treatment combinations were made with two different types of treatment one is concentrations of humic acid @ 10 Kg ha-1 (HA1) and 12 Kg ha-1 (HA2) and the second is the foliar application of Zn and Boron in two different concentrations (1% and 2%) while the single variety of black gram (Mash1008) was used. The humic acid was applied to the soil after dissolvingin the water by the use of a sprinkler in the respective plots before the sowing. The following morphological parameters were used to assess the impact of treatments such asplant height, fresh and dry weight of the plant, number of leaves, leaf area, and LAI while SPAD reading was recorded with a SPAD meter (SPAD-502). The LAI and total chlorophyll content were calculated according to the formula given by (Watson, 1947; Arnon, 1949). Total chlorophyll = (20.2 (D 645) + 8.02 (D 663) × The RBD analysis was carried out through SPSS (Model No-23) while the significance level of the parameters and treatments weretasted at p>0.5%. RESULT AND DISCUSSION The co-ordinal impact of humic acid, boron, and zinc application as soil and foliar application on plant height (cm), fresh and dry weight (g plant-1), the number of leaves, and leaf area (cm2 plant-1) were assessedin black gram. It was observed from the data presented in (Table 1) showed that out of both the concentrations of humic acid (HA1 and HA2), HA2 recorded consistently better as compared to HA1 for all the parameters such as plant height, fresh and dry weight, number of leaves and leaf area. The performance of the treatments among the foliar applications of Zn and Boron with HA1 showed that T4(HA1 + 2% Zn) was found maximum value with highly significantfor all the parameters which were followed by T2 and T5 as compared to the control set whilein case of HA2 in combination with Zn and boron, a similar trend was found for all the parameters except to dry weight of the plant. The data presented in parenthesis (Table 1) showed about the % increase/decrease over the control indicated the same trend concerning gain of growth. Data presented in (Table 2) reveals the impact of treatments on LAI (leaf area index) and SPAD readings at the intervals of 50DAS and at harvest.The performance of the treatments among the foliar applications of Zn and Boron with HA1 showed that T4 (HA1 + 2% Zn) was found to the maximum value with highly significantfor both the parameters which were followed by T2 and T5 as compared to control set while in case of HA2 in combination with Zn and boron, the trends was recorded same for LAI while T2 was recorded best for SPAD reading at both the intervals. It was observed from the data presented in (Table 2) showed that out of both the concentrations of humic acid (HA1 and HA2), HA2 recorded consistently better as compared to HA1 for both the parameters such as LAI and SPAD reading except for SPAD reading at harvest. The data relating to % increase/decrease over control justified the performance of treatments (Table 2). Total chlorophyllcontent (mg g-1) was measured from the leaf of black gram and recorded highest in HA2 as compared to HA1 however, within the HA1, T4 was recorded significantly better as compared to the rest of the treatments while T2 was in HA2 at both the time of intervals showed that HA2 (Fig. 1). However, astrong positive correlation was observed between the SPAD reading and total chlorophyll content (Fig. 2). Humic acid is an important compound that helps in many ways to boost plant growth and development in which one of which is enhancing the capacity to release nutrients in soil followed by the uptake of nutrients. The importance of Zn and boron is already well known,especially in the synthesis of Auxin, the production of carbohydrates, and its translocation from the place of the source to the place of the sink (Pandey and Gupta, 2013; Pandey et al., 2006). The co-ordinal impact of the treatments showed that HA1 and HA2 both were doing well incombination with T4 most of the time except fora few parameters such as SPAD reading and total chlorophyll content T2 was recorded better. The results of the present study areper the findings of (Ibrahim and Ramadan, 2015) who reported that the combined application of humic acid and FA of Zinc benefited the crop up to the yield by manipulating morphological characters such as vegetative and reproductive growth mediated by the enhancing the nutrient release followed by the uptake of the plant (Pandey et al., 2013; Ahmed et al., 2010; Fawzy et al., 2010). It is also reported that humic acid along with Zinc confers supports respiration, photosynthesis, water uptake and protein synthesis (Zhang and Ervin 2004; Sheikha and Al-Malki 2011 and Abu-Muriefah, 2013) while its ultimate impact is reflected in the yield of crop via improving the morphological growth and chlorophyll content.