Cumulative Effect of Botanical Seed Pelleting and Foliar Spray on Morpho Physiological, Leaf Chlorophyll, Gas Exchange and Yield Parameters in Black gram

Genetically pure seeds of black gram [Vigna mungo (L.) Hepper] cv. CO 6 obtained from Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India formed the base material for the study. Field experiments were carried out at the Experimental Farm in the Department of Genetics and Plant Breeding, Faculty of Agriculture, Annamalai University, Tamil Nadu, India (located at 11°24 N, latitude and 79°44 E longitude with an altitude of 5.79 metre above mean sea level) during 2015-2017.
 
Preliminary experiments were conducted with seed pelleting with leaf powders of  two botanicals viz., pungam (Pongamia glabra) and prosopis (Prosopis juliflora) @ 50, 100, 150 and 200g kg^-1 by using gum Arabica as adhesive to study the effect of seed pelleting on morpho physiological, growth and yield parameters of black gram and it was found that seed pelleting with pungam leaf powder @ 150g kg^-1 as the best treatment which has recorded more values for morpho physiological, growth and yield parameters. Further to study the combined effect of seed pelleting and foliar spray, seed pelleting with pungam leaf powder @ 150g kg^-1 along with foliar spray of prosopis and moringa fresh leaf extract was attempted.
 
Fresh young leaves of prosopis and moringa of about 100 g were taken into a mortar with a pinch of water (10 ml/ 100 g fresh material) and ground with a pestle. The juice was extracted by hand pressure and was filtered through the cheese cloth. The solution was re-filtered using No.2 Whatman filter paper. The extract was diluted with distilled water at a ratio of 1:32 (v/v) and used for foliar spray. The extract prepared was stored at 0°C and used within five hours from cutting and extracting and taken out only when needed for use. Hand sprayers were used to spray the extract. The above procedure was followed as per the method suggested by Fuglie (2000). Foliar spray was done with fresh leaf extract @ 2%, 4%, 6% and 8% as per the following treatments.
 
T₀  - Control.
T₁  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 2%.
T₂  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 4%.
T₃  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6%.
T₄  - Seed pelleting with pungam leaf powder @ 150 g kg-1 + foliar spray of prosopis fresh leaf extract @ 8%.
T₅  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of moringa fresh leaf extract @ 2%.
T₆ - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of moringa fresh leaf extract @ 4%.
T₇  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of moringa fresh leaf extract @ 6%.
T₈  - Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of moringa fresh leaf extract @ 8%.
 
 
The field experiments were conducted by adopting randomized block design (RBD) with three replications under normal field condition. The plot size was 4 × 2.5 m². The crop was raised with the spacing of 30 × 10 cm. All the recommended package of practices for black gram were followed and observations on morpho physiological, leaf chlorophyll, gas exchange and yield parameters were recorded.
 
Plant height was recorded by measuring the height of plant from ground level to the tip of main branch using a meter scale and the mean value was expressed in centimetre. The total number of branches plant^-1 was counted and the mean number of branches plant^-1 was recorded as whole number. The biomass production was recorded from ten seedlings selected at random, which were uprooted with the intact root system and washed with water to remove the soil particles, dried under shade for 24 h and then in the hot air oven maintained at 100°C for 24 h. The dried plants were cooled in desiccators for 30 minutes and the mean weight was recorded in grams.

The numbers of flowers opened were periodically counted from the date of sowing till harvest. The day on which 50 per cent of the flower opened was taken as days taken for 50 per cent flowering. Total number of pods in marked ten plants in each treatment was counted and mean number of pods per plant and pod length were recorded replication wise and the mean was expressed in whole number. The pods from ten randomly selected plants earlier tagged were separately harvested and the seeds from each pod were separated, counted and averaged out to get the number of seeds per pod. The pods from ten tagged plants in each treatment were hand shelled. The seeds were cleaned and weighed and the mean seed yield plant^-1 was expressed in grams. The seeds thus obtained were cleaned and weighed to arrive at the plot yield. Seed yield ha^-1 was computed from the seed yield plot^-1 obtained in each of the treatment and expressed in kg ha^-1. 
 
Estimation of leaf Chlorophyll content was done as per the procedure of Yoshida et al., (1971). Gas exchange parameters viz., leaf photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Cs) and intercellular CO₂ concentration (Ci) were measured from two uppermost fully expanded leaves from all the treatments using LICOR-6400XT Portable Photosynthetic System (Lincoln, USA) and expressed as mg CO₂ m^-2 s^-1, mg H²O m^-2s^-1, µmol mol^-1 and mol m^-2 s^-1, respectively. The data on the various parameters studied during the course of investigation were analysed statistically as per the procedure suggested by Panse and Sukhatme (1978). Wherever, the results found significant (‘F’ test), the critical differences (CD) were arrived at five per cent probability level.

Morpho physiological parameters
 
In this present study, the results revealed that the seed pelleting and foliar spray treatments exhibited significant influence on all the growth attributes of black gram (Table 1).  Among the treatments, seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% recorded the highest plant height (48.73 cm). This was followed by seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray with moringa fresh leaf extract @ 2% which recorded plant height of 46.94 cm. The control plants recorded the least plant height of 39.78 cm. Similarly, seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% recorded the maximum number of branches plant^-1 (8.78) and highest dry matter production (14.83 g plant ^-1). The treatment next in order was seed pelleting with pungam leaf powder @ 150 g kg^-1+ foliar spray of moringa fresh leaf extract @ 2%. The least values in number of branches plant^-1 (6.80) and dry matter production (11.90 g plant^-1) were recorded with the control. The minimum number of days to first flowering of 23.23 days was noticed with seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% and  the maximum number of days to first flowering of 28.62 was recorded with the control. Earliness in 50 per cent flowering within 30.12 days was noticed with the seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6%. This was followed by seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray with moringa leaf powder @ 2% which registered 50 per cent flowering in 31.14 days. Number of days to 50 per cent flowering was found extended up to 35.04 days with the control plants.
 

 
The treatment of seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% might have improved the growth of plant during early stage of the crop with increased vigour and associated stronger root system which in turn might have favoured the absorption of more soil moisture and nutrients enabling better growth that resulted in higher yield (Jegathambal, 1996). Similar observations were made by Amira Hagazi and Amal El-Shraiy (2007) in common bean. Plant height is very important criterion for a crop in providing more places for flower production leading to better yield. The foliar spray of prosopis leaf extract would have enabled better nutrient absorption, quick growth and increased plant height with increased number of branches. The increase in dry weight was claimed to be due to enhanced lipid utilization and enzyme activity due to the presence of bioactive substances like auxin in prosopis leaf extract (Rathinavel and Dharmalingam,1999). The higher dry matter accumulation due to seed pelleting cum foliar spray indicated the possible increase in seedling vigour (Basaria Begam, 2001).
 
Turna Doegan and Ahment Zeybek (2009) recorded significant differences between the pelleted and non pelleted seeds in terms of the height of the plants (cm), number of branches per plant and number of capsules in sesame.The cumulative effect of seed pelleting and foliar spray would have helped in better rooting, absorption of more nutrients resulting in higher growth parameters. Paddy seeds hardened with KCl 1% followed by pelleting with pongam leaf powder @ 200g kg^-1 recorded increased growth and biometric characters. It is possible that the bionutrients available in the pelleted seeds might have improved seedling growth resulting in higher growth parameters (Prakash et al., (2013). The benefits of seed treatment with prosopis and pungam leaf extracts to overcome the adverse condition were reported by Rathinavel and Dharmalingam (1999) in uppam cotton and Renugadevi et al., (2008) in clusterbean.
 
Leaf chlorophyll content and Gas exchange parameters
 
Among the treatments, seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% recorded highest chlorophyll ‘a’ (1.03 mg g^-1), chlorophyll ‘b’ (1.11 mg g^-1)  and total chlorophyll content (2.14 mg g^-1) and was followed by seed pelleting with pungam leaf powder @ 150 g kg^-1 + moringa fresh leaf extract foliar spray @ 2% (0.94, 0.93, 1.87 mg g^-1 respectively for chlorophyll ‘a’, chlorophyll ‘a’ and total chlorophyll content) and the minimum was recorded in untreated plants (Table 2).  Among the gas exchange parameters studied viz., photosynthetic rate (Pn), transpiration rate (T_r), intercellular CO₂ concentration (C_i) and stomatal conductance (C_s), it was found that seed pelleting with pungam leaf powder @ 150 g kg^-1 + prosopis fresh leaf extract foliar spray@ 6% recorded more photosynthesis and transpiration rates (27.33 mg CO₂ m^-2 s^-1 and 10.60 mg H₂O m^-2 s^-1) followed by seed pelleting with pungam leaf powder @ 150 g kg^-1 + prosopis fresh leaf extract foliar spray @ 4 % (27.00 mg CO² m^-2 s^-1 and 10.00 mg H²O m^-2 s^-1) and minimum values were recorded by untreated plants (20.25 mg CO² m^-2 s^-1 and 7.55 mg H²O m^-2 s^-1). Similarly seed pelleting with pungam fresh leaf extract @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% recorded higher intercellular CO₂ concentration and stomatal conductance (274.30 µ mol mol^-1 and 0.82 mol^-2 s^-1) whereas control plants recorded minimum values for the same parameters (227.00 µ mol mol^-1 and 0.58 mol m^-2 s^-1).
 

 
Chlorophyll content is found higher in plants treated with seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6%. Because of the invigorative effect of prosopis, the plants would have absorbed more nutrients from the soil and utilized for more chlorophyll production resulting in enhanced photosynthetic activity of treated plants (Sathiya Narayanan et al., 2015). Similar results were reported by Parwar and Kadam (1981) in wheat. The increase in chlorophyll content might be due to the effect of pelleting cum foliar spray treatment over membrane protein synthesis and binding, that lead to more production of photoassimilatory surface and high chlorophyll content (Usha et al., 1999). Similar results were reported by Mvumi Culver et al., (2012) in tomato.
 
A plant bio stimulant when applied singly as a foliar spray modifed plant growth and yield with positive alteration processes under salt stress condition (Rady et al., 2013).  Increased gas exchange parameters with botanical treatments was also reported by Prakash et al., (2013) in rice. Plants treated with prosopis leaf extract @ 1% recorded more photosynthesis, transpiration rates, intercellular CO₂ concentration and stomatal conductance (Sathiya Narayanan et al., 2016). Vigneshwari et al., (2005) observed improvement in physiological and biochemical parameters of hardened and pelleted seeds over control. Paddy seeds hardened with KCl 1% followed by pelleting with pongam leaf powder @ 200g/kg recorded increased gas exchange characters viz., leaf photosynthetic rate, transpiration,   stomatal conductance, intercellular CO₂ concentration (Prakash et al., 2013).
 
Yield parameters
 
Among the treatments, seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% produced lengthier pods, more number of pods plant^-1, pod yield plant^-1, number of seeds pod^-1, seed yield  plant^-1, seed yield ha^-1 and hundred seed weight of  5.60 cm, 26.30, 8.20 g, 7.30, 5.30 g, 795.12 kg ha^-1 and 5.83 g respectively (Table 3). The treatment next in order was seed pelleting with pungam leaf powder @ 150 g kg^-1+ foliar spray of moringa fresh leaf extract @ 2%. The least values in pod length, number of pods plant^-1, pod yield plant^-1, number of seeds pod^-1, seed yield  plant^-1, seed yield ha^-1 and hundred seed weight of 4.40 cm, 21.0, 7.05 g, 6.87, 4.50 g, 658.32 kg ha^-1 and 4.15 g. were recorded with the  untreated control plants (T₁). Similar results were reported by Sathiya Narayanan et al., (2013), Sathiya Narayanan et al., (2016) and Srimathi et al., (2007). Paddy seeds of cv ADT 43 hardened with KCl 1% followed by pelleting with pongam leaf powder @ 200g/kg also recorded the increased yield characters (Prakash et al., 2013).
 

 
Increased yield parameters with prosopis leaf extract @1% along with foliar spray of salicylic acid @100 ppm recorded the higher seed yield and other parameters in black gram under dry land condition (Sathiya Narayanan et al., 2015). Seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis fresh leaf extract @ 6% might be attributed to increase in cell division, cell enlargement, increased number of leaves which eventually produced more number of pods. Similar results were found by Fugile (2001) in onion. Seeds hardened with prosopis leaf extract @ 1% recorded higher seed yield and yield attributing characters (Sathiya Narayanan et al., 2013 and Srimathi et al., 2007 in green gram and Sathiya Narayanan et al., 2016 in black gram).

It was concluded from the above that the seed pelleting with pungam leaf powder @ 150 g kg^-1 + foliar spray of prosopis leaf powder @ 6% recorded higher seed yield and yield attributes in black gram when compared to other treatments and control.