Plant height (cm) at 30, 45, 60 DAS and at harvest
The data on plant height at various growth stages were analyzed statistically are represented in Table 1. Among the treatments seed hardening with 2% CaCl
2 (T
11 and T
1) recorded significantly higher plant height (11.33 cm and 11.00 cm) respectively at 30 DAS in summer 2016. During 2017 as well as in pooled basis 2% CaCl2 (T
11 and T
1) recorded significantly higher plant height (12.50, 11.92 cm and 12.00, 11.50 cm) respectively at 30 DAS. These results are in accordance with the research findings of
Manjunath and Dhanoji (2011). The lowest plant height was recorded (8.00, 8.83 and 8.42 cm) during 2016, 2017 and in pooled analysis respectively with untreated absolute control (T
16) as well as T
9 and T
10. However, the treatment seed hardening with 2% CaCl
2 (T
11 and T
1) remained at par with other treatments
viz., T
2, T
3, T
5, T
12, T
13, T
14 and T
15 at 30 DAS.
At 45 DAS the plant height was significantly superior in the treatment CaCl
2 2% seed hardening + 1% spraying at 30 DAS (T
11) (26.00, 28.33 and 27.17 cm). It was followed by the treatments with NAA 50 mg/L seed hardening + spraying at 30 DAS (T
15) (25.67, 28.00 and 26.83 cm) and NAA 25 mg/L seed hardening + spraying at 30 DAS (T
14) (25.00, 27.33 and 26.17 cm). The treatment CCC 1000 mg/L spraying at 30 DAS (T
8) recorded significantly lower plant height (18.33, 19.00 and 18.67 cm) during 2016, 2017 and in pooled basis, respectively. The treatments showed same trend at 60 DAS and at harvest stage for plant height.
Plant height was increased due to treatments of CaCl
2 and NAA, while decreased due to Cycocel at various growth stages
viz., 45 DAS, 60 DAS and at harvest in green gram.
The decrease in plant height with cycocel may be attributed to anti - auxin activity of Cycocel. It blocked the synthesis of IAA in the plant system. The mechanism of reduction of plant height by spraying with Cycocel also appears due to reduced cell size and cell wall thickening or reduction in the cell division activity
(Ginzo et al., 1977). Similar results observed by
Sujatha (2014) in chickpea and
Kinjal (2017) in black gram.
It was observed that NAA showed a positive effect among the different treatments. The application of auxin in plant has a role in the stimulation of RNA and protein synthesis and greater enhancement in photosynthesis rate, increased in cell elongation as well as cell division and cell wall plasticity, which ultimately showed the enhancement in various growth parameters. The above finding were in agreement with the results reported by
Ananthi and Mallika (2014) in green gram,
Sunil Jadhav (2016) and
Kinjal (2017) in black gram,
Pothalkar (2007) in pigeon pea,
Sujatha et al. (2017) in chickpea.
Number of branches per plant at 30, 45, 60 DAS and at harvest
The results on number of branches per plant were analyzed statistically and represented in Table 2. Among the treatments, seed hardening with CCC 1000 mg/L (T
13 and T
3) recorded significantly higher number of branches per plant (3.70) and absolute control (T
16) and T
7 recorded lowest (3.23) at 30 DAS. However, the treatments T
11 and T
1, T
12 and T
2 as well as T
15 and T
5 remained at par with the treatments T
13 and T3 at 30 DAS in pooled analysis. On pooled basis, CCC 1000 mg/L seed hardening + spraying at 30 DAS (T
13) recorded significantly maximum (6.28, 8.13 and 8.67) number of branches per plant than untreated absolute control (4.94, 6.27 and 6.67) at 45 DAS, 60 DAS and at harvest, respectively.
The reduction in plant height due to growth retardants is mainly seem to have released the apical dominance and diversion of the plant metabolites from vertical growth to horizontal growth and thereby more number of branches per plant. As the apical dominance is removed usually the plant itself adjusts to encourage the growth of auxiliary buds which then converted into branches. Similar results were obtained in pigeon pea by Arjun
Sharma et al., (2003) and
Manjunath and Dhanoji (2011) and
Sujatha (2014) in chickpea.
Leaf area at 30 DAS, 45 DAS, 60 DAS and at harvest (cm2 plant-1)
The data regarding leaf area per plant were recorded and analyzed statistically are furnished in Table 3. The data revealed that pre-sowing seed hardening with 2% CaCl2 (T
11 and T
1) recorded significantly higher leaf area per plant (194, 222, 208 cm
2 and 191, 220, 206 cm
2) while lower total leaf area per plant was observed (102, 114 and 108 cm
2) in untreated absolute control (T
16) at 30 DAS during summer 2016 and 2017 seasons as well as in pooled analysis, respectively. The treatments
viz., CCC 1000 mg/L (T
13 and T
3) (180, 210 cm
2 and 177, 209 cm
2) remained at par with the treatments 2% CaCl
2 (T
11 and T
1) at 30 DAS during 2016 and 2017 seasons, respectively. The treatment CaCl
2 2% seed hardening + 1% spraying at 30 DAS (T
11) recorded significantly highest total leaf area per plant (422, 607 and 395 cm
2) and remained at par with the treatments T
13 (411, 594 and 387 cm
2), T
15 (399, 583 and 374 cm
2) and T
12 (397, 576 and 368 cm
2) at 45 DAS, 60 DAS and at harvest, respectively. The untreated absolute control (T
16) recorded significantly the lowest (270, 419 and 244 cm
2) leaf area per plant.
The increased in leaf area by seed hardening and foliar spraying with CaCl
2, Cycocel and NAA might be due to increase in cell division, cell enlargement as well as induce more extensive and denser network of veins and ribs and there by increased foliar leaf area. These results are conformity with the finding of
Ginzo et al., (1977) in chick pea,
Shinde and Jadhav (1995) in cowpea,
Prabhu (2000) in blackgram,
Pothalkar (2007) in pigeonpea,
Prakash et al., (2013) in rice and
Kinjal (2017) in black gram.
Kalubarme and Pandey (1979) also reported that leaf area increased with an increase in time to a maximum coinciding with maximum top growth and steady decline at later stage.
Dynamics of dry matter accumulation
Both treatments and sampling time
i.
e. growth stage had a significant effect on dry matter accumulation (g plant
-1). Production of dry matter was slow during the first month after sowing, which is typical for legumes adapted to winter conditions
(Zapata et al., 2019). In early growth phase larger portion of total dry matter was shared by the leaves than the stem. The dry matter accumulation in pods initiated after 30 DAS with reproductive parts like flowers and continued to increase upto the harvest.
In the present study, significant differences were observed in the total dry matter per plant. The data regarding total dry matter accumulation per plant were analyzed statistically and furnished in Table 4.
Total dry matter production at various growth stages
The total dry matter production per plant is aggregate of stem, leaf, root and reproductive dry matter accumulation at respective growth stages. It was increased progressively and differed significantly at all the growth stages from sowing to harvest in green gram. The results pertaining to the total dry matter (TDM) production indicated significant differences and revealed that pre-sowing seed hardening with 2% CaCl
2 (T
11 and T
1) recorded highest total dry weight per plant (4.393, 5.043, 4.718 and 4.383, 5.000, 4.692 g) while lowest total dry matter production was recorded (3.450, 4.033 and 3.742 g) in untreated absolute control (T
16) at 30 DAS during summer 2016, 2017 seasons and in pooled analysis, respectively. The treatment with CaCl
2 2% seed hardening + 1% spraying at 30 DAS (T
11) recorded highest total dry matter accumulation per plant (13.013, 14.537 and 13.775 g) at 45 DAS, at 60 DAS (27.057, 30.417 and 28.737 g) and at harvest (29.720, 33.420 and 31.570 g) during summer 2016, 2017 seasons and in pooled analysis, respectively (Table 4). The increase in TDM production towards maturity may be due to indeterminate growth pattern, higher rate of CO
2 fixation and RuBP carboxylase activity during crop growth. The association of TDM partitioning with grain yield was more significant at all the stages of crop growth. Thus, TDM production and partitioning is an important parameter in boosting the source-sink relationship and ultimately yield potential. Similar observations were also made by
Nam et al., (1998), Katti et al., (1999), Manjunath (2007),
Sujatha (2014) in chickpea and
Patil et al., (2007) in groundnut. Thus, the total dry matter is composed of more with the leaf and stem dry weight and little with root dry weight during vegetative growth phase. But during reproductive growth phase, reproductive parts like pods, flowers contributes more as compared to leaf, stem and root dry weight.
Murthy et al., (2002) corroborated the increase in dry matter in any genotype might reflect in increase in yield contributing characters and ultimately final economic yield and positive correlation of dry pod yield with dry matter accumulation.
Seed yield per plant (g plant-1)
The data regarding seed yield per plant and seed yield per hectare were recorded and analyzed statistically are furnished in Table 5. The treatment CaCl
2 2% seed hardening + 1% spraying at 30 DAS (T
11) recorded significantly higher values of seed yield per plant (13.07, 14.20 and 13.63 g) and remained at par with T
13 (12.60, 13.93 and 13.27 g), T
15 (12.47, 13.60 and 13.03 g) and T
12 (12.13, 13.27 and 12.70 g) during 2016, 2017 and on pooled basis, respectively. Whereas, the treatment of absolute control (T
16) recorded significantly lowest yield per plant (8.07, 9.40 and 8.73 g, respectively).
Seed yield per hectare (kg ha-1)
The significantly highest seed yield per hectare (949, 1006 and 978 kg ha
-1) was recorded by the treatment T
11 which remained at par with the treatments T13 (922, 964 and 943 kg ha
-1) and T
15 (893, 917 and 905 kg ha
-1). While significantly the lowest seed yield per hectare was observed in the absolute control (639, 679 and 659 kg ha
-1) during 2016, 2017 and in pooled analysis, respectively (Table 5).
Improvement in yield could happen in two ways
i.
e., by adopting the existing varieties to grow better in their environment or by altering the relative proportion of different plant parts so as to increase the yield of economically important parts. The influence of plant growth regulators and seed hardening chemicals significantly increased the seed yield. The present study also revealed that increase in seed yield was significantly higher in seed hardening + spraying with CaCl
2 (2% seed hardening and 1% spraying) followed by Cycocel 1000 mg/L and NAA 50 mg/L. This could probably be due to beneficial effects of agrochemical and plant growth regulator treatments which help in enhancement of photosynthesis and nitrogen metabolism which are the major physiological process influencing plant growth and development. The treatments of CaCl
2 was significantly superior as compared to other treatments in enhancing the plant height, number of branches per plant, leaf area, dry matter production and thereby seed yield. The increase in the higher yield may be due to better carbon assimilation, better accumulation of carbohydrates and reduced respiration in plants. These results are in agreement with the findings of
Mahabir Singh and Rajodia (1989) in soybean and
Pothalkar (2007) in pigeon pea.