Growth attributes
Plant height
The data in Table 1 show that application of P
2O
5 @ 60 kg/ha (P
3) recorded the significantly maximum plant height at cutting-I, II, III and IV (7.64, 11.98, 11.01 and 10.74 cm, respectively) as compared to control P
0 (5.82, 8.06, 7.21 and 6.86 cm, respectively) and P
1 (6.99, 10.01, 9.06 and 9.51 cm, respectively) but P
2 (7.25, 11.67, 10.69 and 10.47 cm, respectively) remains at par with P
3. Higher ratio of phosphorus application increased the plant height that may be due to favourable effect of phosphorus on nitrogen transformation leading to accumulation and metabolism of carbohydrates in plants. Similar results were reported by
Kumar et al., (2016) and
Datta et al., (2017). The data in Table 1 show that application of foliar nitrogen @ 2.0% (N
3) recorded the significantly maximum plant height at cutting-I, II, III and IV (7.68, 12.23, 11.11 and 11.54 cm, respectively) as compared to control (N
0) (5.88, 8.11, 7.29 and 6.84 cm, respectively), foliar application of nitrogen @ 1.0% (N
1) (7.05, 10.21, 9.29 and 8.67 cm, respectively) and 1.5% (N
2) (7.09, 11.17, 10.28 and 10.53 cm, respectively). The positive influence of the nitrogen on plant height might be due to the fact that nitrogen is required for cell elongation while, the plant height was least in the control. Similar findings were reported by
Muniramappa et al., (1997) and
Patidar et al., (2004).
Leaf area per plant (cm2)
The data in Table 1 show that application of P
2O
5 @ 60 kg/ha (P
3) recorded the significantly maximum leaf area at cutting-I, II, III and IV (25.37, 27.35, 27.05 and 26.38 cm
2/plant, respectively) as compared to control P
0 (15.63, 16.82, 16.42 and 15.71 cm
2/plant, respectively) and P
1 (20.10, 22.09, 21.89 and 21.21 cm
2/plant, respectively) but P
2 (24.43, 26.52, 26.22 and 25.52 cm
2/plant, respectively) remains at par with P
3. Increased leaf area per plant during periodic stages probably resulted in more interception of solar radiation and also phosphorus is noted especially for its role in capturing and converting the sun’s energy into useful plant compounds leading to formation of greater amount of photosynthates. Similar findings were reported by
Jat et al., (2013) and
Dar et al., (2016). The data in Table 1 show that application of foliar nitrogen @ 2.0% (N
3) recorded the significantly maximum leaf area per plant at cutting-I, II, III and IV (26.82, 28.18, 27.87 and 27.18 cm
2/plant, respectively) as compared to control (N
0) (16.30, 17.57, 17.16 and 16.47 cm
2/plant, respectively), foliar application of nitrogen @ 1.0 % (N
1) (19.49, 22.01, 21.84 and 21.15 cm
2/plant, respectively) and 1.5 % (N
2) (22.92, 25.01, 24.70 and 24.01 cm
2/plant, respectively). Linear increases in leaf area per plant were observed with increase in the foliar application of nitrogen levels. This could be due to production of more number of leaves, branches and enhanced availability of nitrogen at the appropriate time, which has increased the leaf area per plant. Similar results were noticed by
Mehta et al., (2010) and
Anupama et al., (2017).
Number of nodules per plant
The data in Fig 1 indicated that application of 60 kg/ha dose of (P
3) fertilizer recorded the significantly maximum number of nodules per plant (58.17) as compared to P
0 (control) (46.87) and P
1 (48.13) but P
2 (56.20) remains at par with P
3. The adequate supply of phosphorus improved survival and growth of rhizobia, rate of symbiotic infection and microbial activity in plant root nodules.
Valverde et al., (2002) and
Singh et al., (2012) observed in their study on
Discaria trinervis that the size of nodules and the proportion of nodule tissue were stimulated by phosphorus application. The data in Fig 1 show that foliar nitrogen @ 2% (N
3) recorded highest number of nodules/plant (53.33), which found non-significant among each other. These results were similar with the findings of
Roy et al., (2016) and
Shete et al., (2018).
Chlorophyll content (mg/100 g)
The data in Table 2 show that application of 60 kg/ha dose of P
2O
5 (P
3) fertilizer recorded the significantly maximum total chlorophyll content (2.32 mg/100 g) in plant leaves as compared to P
0 (control) (1.79 mg/100g) and P
1 (2.06 mg/100g) but remains at par with P
2 (2.25 mg/100 g). Phosphorus is a necessary nutrient for the biosynthesis of chlorophyll, so higher amount of phosphorus leads to higher chlorophyll content of leaves (
Ambrose and Easty, 1977). Similar results were recorded by
Dar et al., (2015) and
Gendy et al., (2018). Application of foliar nitrogen @ 2.0% (N
3) recorded the significantly maximum total chlorophyll content (2.39 mg/100g) as compared to control (N
0) (1.87 mg/100 g), foliar application of nitrogen @ 1.0% (N
1) (2.02 mg/100g) and 1.5% (N
2) (2.14 mg/100 g). This might be due to increased nitrogen supply which would retard leaf senescence and improve photosynthate and nitrogen availability for seed biomass. These results obtained are closely similar with earlier findings recorded by
Mitra and Ghildiyal (1988) and
Kulsum et al., (2007).
Fresh leaves yield
The data in Table 3 show that application of P
2O
5 @ 60 kg/ha (P
3) recorded significantly maximum total fresh leaves yield per plot (kg) and per hectare (q) (0.567 and 139.10) as compared to control (P
0) (0.447 and 114.50) and P
1 (0.499 and 123.10) but remains at par with P
2 (0.551 and 131.5). Application of phosphorus increased nutrients availability to the crop during the growing season which led to greater synthesis and utilization of assimilates into the leaves and ultimately improved the performance of various yield attributes
viz. fresh leaves yield per plot (kg) and per hectare (q). Similar results were noticed by
Sharma et al., (2014) and
Nikfarjam and Aminpanah (2015). Application of foliar nitrogen @ 2.0% (N
3) enhanced the total fresh leaves yield per plot (kg) and per hectare (q) (0.580 and 141.66) significantly over control (N
0) (0.458 and 111.19), N
1 (0.498 and 124.48) and N
2 (0.528 and 130.87). The increased levels of foliar nitrogen enhanced the metabolic process like photosynthesis, levels of nucleic acids, soluble proteins, carbohydrates, which results in luxuriant growth of the plant and production of more fresh yield. These results similar with the findings of
Meena et al., (2006) and
Khan et al., (2018).
Dry leaves yield
The data in Table 3 show that application of P
2O
5 @ 60 kg/ha (P
3) recorded significantly maximum total dry leaves yield per plot (kg) and per hectare (q) (0.027 and 20.01) as compared to P
0 (control) (0.022 and 12.90) and P
1 (0.024 and 15.29) but remains at par with P
2 (0.026 and 19.07, respectively). Adequate level of phosphorus along with increased mobility of other nutrients had a strong positive effect on photosynthesis that could enhance the plant’s ability to produce more assimilates which were reflected in the higher amount of dry matter accumulation at an accelerated pace as evidenced from high leaf area per plant values resulting in higher amount of biomass. Similar results were noticed by
Godara et al., (2013) and
Singh et al., (2014). Application of foliar nitrogen @ 2.0% (N
3) enhanced the total dry leaves yield per plot (kg) and per hectare (q) (0.028 and 22.38) significantly over control (N
0) (0.22 and 11.73), N
1 (0.024 and 14.87) and N
2 (0.026 and 18.30). Foliar nitrogen preferentially increased the metabolic processes like photosynthesis, enhanced levels of nucleic acids, soluble proteins and carbohydrates which resulted in higher dry matter production and sink size. Similar results were observed by
Godara et al., (2018) and
Bhadru et al., (2019).
Quality attributes
Crude protein content in leaves (%)
The data in Table 2 show that application of P
2O
5 @ 60 kg/ha (P
3) recorded significantly maximum crude protein content (5.28%) over P
0 (control) (3.72%) and P
1 (4.34%) but remains at par with P
2 (5.13%). The increase in these parameters due to P fertilization led to an increased uptake of nutrient in the present study. Higher nitrogen in plant parts is directly responsible for higher protein because it is a primary component of amino acids which constitute the basis of protein. These results are in close conformity with the findings of
Gupta et al., (2009) and
Dubey et al., (2012). Data in Table 2 show that significantly maximum crude protein content was recorded under foliar nitrogen @ 2.0% (N
3) (5.75%) over control (N
0) (3.60%), N
1 (3.98%) and N
2 (5.14). Higher nitrogen in plant parts is directly responsible for higher protein because it is a primary component of amino acids which constitute the basis of protein. Similar results were observed by
Pandya and Bhatt (2007) and
Naveen (2010).
Ascorbic acid content in leaves (mg/100 g)
Table 2 shows that ascorbic acid content in leaves was recorded significantly maximum with application of P
2O
5 @ 60 kg/ha (P
3) (218.15 mg/100 g) over P
0 (control) (182.42 mg/100 g) and P
1 (205.15 mg/100 g) but remains at par with P
2 (215.34 mg/100g). Similar findings were reported by
Singh et al., (2012) and
Zikalala et al., (2016). Table 2 further shows that significantly maximum ascorbic acid content in leaves was recorded under foliar application of nitrogen @ 2.0% (N
3) (222.42 mg/100 g) over control (N
0) (188.86 mg/100 g), N
1 (199.74 mg/100 g) and N
2 (210.04 mg/100 g). Similar results were noticed by
Moreira et al., (2003) and
Gupta et al., (2009).
Economics
Table 4 shows that application of P
2O
5 @ 60 kg/ha (P
3) recorded significantly higher net return and B:C ratio (Rs. 162430 and 2.57) over control P
0 and P
1 but remains at par with P
2. Similar findings were reported by
Bhunia et al., (2006) and
Godara et al., (2017). Table 4 shows that application of foliar application of nitrogen @ 2.0% (N
3) recorded significantly higher net return and B:C ratio (Rs. 188536 and 2.97) over N
0 (control), N
1 and N
2. Similar results were reported by
Godara et al., (2018) and
Dhaka et al., (2020).