Effect of seed priming on growth and seed yield in kabuli chickpea (Cicer arietinum L.) varieties 

Chickpea (Cicer arietinum L.) is a old world pulse crop commonly known as bengalgram, garbanzo bean, gram, chana, kadlee and is the third most important pulse crop in the world after beans and peas. Chickpea is popularly cultivated in sub tropical and semi-arid to warm temperate regions under dry season. Chickpea is valued for its nutritive seed composition with high protein content and used increasingly as a substitute for animal protein. It also accounts for efficient soil enrichment by symbiotic nitrogen fixation and it has ability to meet more than 70 per cent of its nitrogen requirement from symbiotic nitrogen fixation, besides being drought tolerant.
       
Chickpea is classified based on seed size, shape and colour. Two main types of chickpea cultivars grown globally are kabuli and desi, representing two diverse gene pools. Where, white seeded ‘kabuli chickpea’ being grown in Northern parts and brown seeded ‘Desi’ type grown in Southern parts of India. The average world production of chickpea is 137.31 lakh tonnes from an area of 139.81 lakh hectare with an average productivity of 982 kg per hectare. In Asia, India is the largest producer of chickpea contributing over 70 per cent of the world production occupying an area of 86.80 lakh hectare with a production of 80.90 lakh tonnes and with productivity of 932 kg per hectare (Anonymous, 2017).
       
Globally and nationally the area, production and productivity of kabuli chickpea is very low as compared to desi type of chickpea. However, world of chickpea is predominanted by desi type which accounts to 80 per cent of production as compared to kabuli type which accounts to 20 per cent of production. Poor germination and low seed viability are among the serious problems limiting the production of kabuli chickpea. The use of high quality seeds is essential to establish a suitable population in fields, giving better financial results (Krzyzanowski et al., 1993). However, the use of kabuli seeds of low physiological quality is a common practice under tropical and subtropical production conditions leading to inadequate plant population in the field. It is reported that seed priming is one of the most important development to help rapid and uniform germination and emergence of seeds and to increase seed tolerance to adverse environmental conditions (Heydecker et al., 1973; Harris et al., 1999). Seed priming has presented promising and even surprising results for many seeds including the legume seeds (Bradford, 1986). The few studies on chickpea are not overemphasized and are encouraging, but more information is required before its use as a routine practice to derive direct benefits of seed priming which involves faster emergence, better, more and uniform stands, less need to re-sow, more vigourous plants, better drought tolerance, earlier flowering, earlier harvest and higher seed yield and the indirect benefits reported were earlier sowing and harvesting of crops and increased willingness to use of fertilizer because of reduced risk of crop failure (Harris et al., 2001). Production and productivity depends on seedling emergence and vigour of the seed crop. There are very few studies available on performance of kabuli chickpea to seed priming. This urges the necessity of simple, feasible and viable technology to improve seedling vigour and seedling establishment of crops under varied environmental conditions. Keeping this in view, research was conducted to study the effect of seed priming on growth and seed yield in kabuli chickpea (Cicer arietinum L.) varieties.

The experiment consisted of two kabuli chickpea varieties viz., V₁: BG1105 and V₂: MNK-1 and nine seed priming treatments viz., T₁: Control, T₂: Hydro priming, T₃: Calcium chloride @ 2 %, T₄: ZnSO₄ @ 2 g per kg of seed, T₅: Cowurine @ 25 %, T₆: Panchagavya @ 3 %, T₇: Custard apple leaf extract @ 3 %, T₈: Rhizobium (GR-2) @ 4 ml per kg of seed and T₉: Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed. The field experiment was conducted at Water and Land Management Institute (WALMI) farm, Dharwad during rabi 2015-16 and 2016-17 in split plot design with three replications.

Procedure for preparation of seed priming
 
Different seed priming treatments viz., Calcium chloride, Zinc sulphate, Cowurine, Panchagavya, Custard apple leaf extract, Rhizobium (GR-2), Sprint (Mancozeb 50% + Carbendazim 25 % WS) were added to sterilized distilled water to get the desired per cent of solution as per treatment concentrations and used for soaking the seeds as per the required weight by volume ratio of seed to solution (1:2) for four hours (The time of soaking was from 7 am to 11 am). Then, the seeds were decanted and air dried under shade and used for sowing. Whereas no treatment was imposed for control, and for hydropriming the seeds were soaked for four hours in weight by volume ratio of seed to solution (1:2). The biometric observations on growth parameters were recorded at three stages of the plant growth viz., vegetative, flowering and harvesting. For recording various parameters five plants at random from net plot area were selected and tagged in each plot for taking observations on plant height, chlorophyll content. However, the yield attributing parameters like the number of secondary branches per plant, number of pods per plant, hundred seed weight, seed yield per plant and hectare were recorded at harvest. Whereas, for recording the observations on root nodules per plant, five plants from the net plot were randomly uprooted at 60 days after sowing. Statistical analysis was done as per the procedure described by Gomez and Gomez (2010). 

Effect of kabuli chickpea varieties on growth, yield and attributing parameters
 
The plant growth, seed yield and quality parameters are greatly influenced by genetic makeup of the varieties. Besides, several biotic, abiotic, agronomic and management practices. In the present study, varietal differences with respect to field performance have been noticed in kabuli chickpea during 2015-16 and 2016-17. From the results of the pooled data, significant variation in growth, seed yield and yield attributes were observed in kabuli chickpea varieties irrespective of seed priming. In general, from the results of the pooled data BG1105 (V₁) registered significantly highest plant height (22.38, 38.29 and 43.19 cm) (Table 1), chlorophyll content (42.96, 48.11 and 45.94 SPAD value) (Table 2) as compared to MNK-1 (V₂) with plant height (20.19, 33.41 and 37.21 cm) and chlorophyll content (38.36, 42.49 and 40.05 ) at 30, 60 DAS and harvest respectively, the probable reason may be mainly due to efficient accumulation of photosynthates in the vegetative parts during early stage of plant.
 

 

       
 
Further, BG1105 (V₁) also recorded significantly higher number of root nodules at 60 DAS (19.63) (Table 3), number of secondary branches (23.11) (Table 3), number of pods per plant (45.90) (Table 3), seed yield per plant (28.92 g) (Table 4) and per hectare (13.00 q) (Table 4) was highest in BG1105 (V₁) as compared to MNK-1 (14.48, 14.22, 22.22 g and 11.72 q, respectively). From these results, it was found that both varieties differed significantly for growth parameters due to their genetic differences. Such differential genotypic response on growth parameters were also in conformity with the findings of Merwade (2000), Gnyandev (2009) and Sushma (2013) in chickpea.
 

 

 
Effect of seed priming on growth and seed yield and yield attributing parameters in kabuli chickpea varieties
 
Seed priming had higher impact on crop growth, seed yield and yield attributing parameters during 2015-16 and 2016-17. In the present investigation, different seed priming treatments used under study had similar effect during both years. From, the results of pooled data, significantly higher plant height at 30 (27.51 cm), 60 DAS (43.28 cm) and at harvest (48.01 cm) was recorded in T9 [Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed] as compared to other treatments and T₁ (control) (20.90, 37.08 and 42.34 cm, respectively) (Table 1) this might be due to seed priming with sprint, a contact and systematic fungicide which mainly helps in protection of seed (as the kabuli chickpea seeds have very soft, delicate seed coat that are sensitive and prone to damage by both biotic and abiotic factors) from invading and survival of wide range of fungal pathogens around rhizosphere throughout the crop period and provides a favorable condition by enhancing sufficient nutrient uptake from rhizosphere through better root system. In addition, sprint is a composed of micronutrients viz., Zinc (Zn) and Manganese (Mn), where Zn helps in the synthesis of tryptophan which is a precursor of Indole acetic acid; it also has an active role in the production of an essential growth hormone viz., auxin which might helped in triggering the metabolic activity of enzymes required for seed germination leading to rapid cell division, cell enlargement and radical emergence leading to formation of effective root system with early and uniform field emergence with better plant growth (Anonymous, 2018). These results are in conformation with the findings of Anitha et al., (2013) in Soybean and Xalxo et al., (2007) in chickpea.
 
Similarly, seed priming had significant effect on chlorophyll content (SPAD value) during 2015-16 and 2016-17. From the results of pooled data, significantly highest chlorophyll content (SPAD value) at 30 (50.59), 60 (55.76) and 75 days after sowing (DAS) (53.45) was recorded due to seed priming with T₉ [Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed] as compared to other treatments and control (42.12, 47.57 and 44.07, respectively) (Table 2) this might be due to presence of Zinc in sprint which might have played very important role in plant metabolism by influencing the activities of hydrogenase and carbonic anhydrase, stabilization of ribosomal fractions and synthesis of cytochrome helpful in chlorophyll synthesis, in addition to this, Mn might have played some role in maintenance of chloroplast membrane structure, which occurs in activation of chloroplast RNA polymerase and splitting of water and the presence of mangano protein catalyzes the oxygen evolution which indicates the higher rate of photosynthetic activity leading to higher chlorophyll content and vegetative growth of plant. Further, seed priming with T9 [Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed] recorded significantly higher root nodules (21.50) per plant at 60 DAS compared to other treatments and control (16.50) (Table 3). The probable reason may be due to the presence of Zn in sprint which is a major nutrient required by rhizobia for atmospheric nitrogen fixation in legumes and are considered as important constituents of nitrate reductase, nitrogenase, which is required for both synthesis and activity of enzymes (Campo et al., 2000). Formation of more number of nodules per plant, leads to more nitrogen fixation in plant roots which ultimately increases physiological activity by translocation of nutrients from root to growing parts of plant leading to better vegetative growth, yield attributing parameters and yield (Anonymous, 2018).
       
Likewise, from the results of pooled data significantly higher number of secondary branches (23.38) was affected due to seed priming with T9 [Sprint] as compared to other treatments and control (T₁) (17.98, respectively) (Table 3), this may be due to the presence of Zn which is required for the synthesis of tryptophan, which act as a precursor of Indole acetic acid, and helps in production of auxin. While the presence of Mn in sprint also favours breakdown of Indole acetic acid, leading to rapid cell division, cell elongation and translocation of nutrients from root to meristematic part of plants leading to increased number of primary and secondary branches. Similar results were also reported by Anitha et al., (2013) in Soybean and Xalxo et al., (2007) and Padamini et al., (2015) in chickpea.
       
Significantly higher number of pods per plant, and test weight was recorded due to seed priming during 2015-16 and 2016-17. From the results of pooled data significantly higher number of pods per plant (44.73) (Table 3) and test weight (35.32 g) (Table 4) was recorded in T9 [Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed] as compared to other treatments and control (T₁) (32.25 and 29.93 g, respectively), this may be due to the additional effect of presence of Zinc in sprint, where the Zn finger-transcription factors that are involved in the development and function of floral tissues such as anthers, tapetum, pollen and pistil secretory tissues leading to the formation of more number of flower, seed set and translocation of metabolites from source (vegetative parts) to sink (pod), with increased seed filling and increased test weight. These results are in conformation with Anitha et al., (2013) in Soybean and Xalxo et al., (2007) and Padamini et al., (2015) in chickpea.
 

 

       
From the results of pooled data, significantly higher seed yield (16.59 q/ha) was recorded in T₉ [Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed] and followed by T₄, T₃, T₆, T₇, T₈, T₅ and T₂, whereas control (T₁) exhibited lower seed yield  (12.09 q/ha, respectively) (Table 4), this may be due to seed priming which improves rRNA integrity, repairing of cell constitutes and increased activity of protein synthesis to permit subsequent germination resulting in early seed germination, uniform plant stand and exposure of these plants for proper harness of sunlight, for photosynthesis and its translocation of food metabolites to different growing parts and leading to better vegetative growth with increased number of primary and secondary branches per plant which add together for production of more number of flowers, pods, seeds per pod and test weight of seed leading to higher seed yield per plant and per ha. Similar effect of seed priming on seed yield and yield attributing parameters were reported by Anitha et al., (2013) in Soybean and Xalxo et al., (2007) and Padamini et al., (2015) in chickpea. However, the growth, seed yield and yield attributing parameters did not differ significantly due to interaction of seed priming treatments and varieties.

From the present investigation, it can be concluded that, BG1105 variety and seed priming with Sprint (Mancozeb 50 % + Carbendazim 25 % WS) @ 2 g per kg of seed registered significantly higher seed yield and yield attributing characters compared to MNK-1 variety and control, respectively.