Effect of Sowing Dates and Seed Priming on Agrometeorological Indices and Soil Moisture Regimes of Chickpea in North Central Plateau Zone NCPZ of Odisha

Chickpea (Cicer arietinum L.) is the third most important pulse crop in the world, with 14.84 million hectares in cultivation, 15.08 million tons produced and an average yield of 1.01 t/ha (all numbers from FAOSTAT, 2021). It is one among India’s most important Rabi pulse crops. Chick pea farming covers 105.61 million hectares (ha), yields 112.29 million tons (t) and yields 1063 kilograms per hectare (kg/ha) in India (Samriti et al., 2020). It is often grown in the winter on fallow fields where soil moisture has been kept following the harvest of kharif paddy. According to research, the best sowing period for chickpeas has a substantial impact on both yield and quality. The time of seeding has a substantial effect on chickpea yield and quality (Ali et al., 2018). When the sowing timing is perfect, the plant has plenty of time to grow and mature, which improves yield.  Flowering at a time when frost is unlikely is also beneficial in terms of crop protection (Chopada et al., 2016). Early or late seeding reduces growth and development, which both diminish yield (Husnain et al., 2015). Early seeding yields a lesser yield because fewer pods and seeds develop. Late sowing affects crop output due to the shorter time for seed development (Girma et al., 2017; Mubvuma et al., 2015). Crop output decreased by 28% for every 10 days if crop sowing was postponed (Ray et al., 2017). The single most important element in influencing chickpea production is sowing date, making it a critical non-monetary input.

About 30% of the area remains fallow after the harvest of rice in Eastern India (Hazra and Bohra, 2020). During the rabi season due to the lack of irrigation facilities, the growing of crop depends on the effective utilization of the carry-over residual moisture of the previous crop. (Narendra et al., 2012). Approximately 70 per cent of the chickpea in India is grown under rainfed conditions (Choudhary et al., 2016).  As chickpea has an indeterminate growth habit, the yield accumulation depends on continuous and simultaneous vegetative and reproductive development starting from the commencement of flowering, therefore the moisture availability during all the growth stages is also one of the important factors for higher potential yield (Asaf et al., 2023). Chickpea in Odisha is usually grown on stored or residual soil moisture after the harvest of kharif paddy and mostly faces moisture stress throughout its life cycle which drastically reduces the yield. Moisture stress affects the nitrogen fixation of chickpea crop, its uptake and assimilation. Nitrogen fixation isbreduced due to a reduction in leghaemoglobin in the nodules, specific activity of nodule and in the number of nodules. In the rainfed areas, out of whatever little rainfall that is received during the season,not all is available to the crops, but  a major part of it is lost as run off and evaporation. Therefore, intensive efforts are required to develop soil and moisture conservation practices to attenuate the moisture stress so that the food production can be maximized with minimal environmental degradation. The solution to this problem is adoption of in-situ moisture conservation practices (Kumar et al., 2008; Rathore et al., 2010). The adoption of eco-friendly and economical techniques such as seed priming and in situ application of crop residues are of vital importance (Rakshit and Singh, 2018; Sarkar et al., 2020). Seed priming ensures vigorous and uniform germination of the seeds, good crop stand and enables the crop to mitigate the biotic and abiotic stresses and improves the quality of the produce (Paparella et al., 2015; Chatterjee et al., 2018; Zulfiqar, 2021) and enhances yield potential (Marthandan et al., 2020). In situ application of crop residues helps to conserve more rain water in soil by reducing the runoff of water from the soil surface andloss of water through evaporation under water scarcity situations (Singh et al., 2013; Paliwal et al., 2011). They also help to balance and regulate the soil profile temperature (Hari Ram et al., 2012).

A field experiment entitled “Effect of sowing dates and seed priming on agrometeorological indices and soil moisture regimes of Chickpea in NCPZ of Odisha” was conducted at Experimental Block of Regional Research and Technology Transfer Station, Keonjhar, Odisha, India during the Rabi season for two consecutive years i.e., 2021-22 and 2022-23. The field experiment was laid out in factorial RBD design with three replications and two factors, the first one being the dates of sowing (Factor A) and the second one being moisture conservation practices (Factor B). There were 3 dates of sowing in Factor A (D₁-25 November, D₂-5 December, D₃- 15 December) and 5 moisture conservation practices in Factor B (M₁- Control, M₂- Seed priming with water for 8 hours, M₃- Osmopriming (Seed priming with CaCl₂ solution @0.5% for 8 hours), M₄- Straw mulch@ 5 t/ha and M₅- Straw mulch@ 5 t/ha +Seed priming with CaCl₂ solution @0.5% for 8 hours). Altogether there were 15 treatment combinations. The test crop variety taken was JAKI - 9218. The crop was sown with a row spacing of 30 cm as per the dates of sowings. Fertilizers were applied on a soil test basis. A dose of 20 kg N, 40 kg P₂O₅ and 40 kg K₂O/ha was applied to all plots as a basal dose just below the seed at the time of sowing.  N and P₂O₅ were applied through urea and single SSP and given as basal. Two irrigations were given, 5 cm each, one at pre flowering stage and the other at pod-formation stage coinciding with the critical stages of crop growth during both the years of experimentation. The amount of rainfall received during the crop growth period of chickpea was 87.4 mm (25^th Nov sowing), 85.2 mm (5^th Dec sowing) and 40.8 mm (15^th Dec sowing) during the year 2021-22 whereas in the year 2022-23, the crop did not receive any rainfall during its growth period. All recommended packages of practices were followed for cultivation as per the treatments.
 
Observations recorded
 
Morphological characters
 
The observations of plant height, as well as the number of primary and secondary branches, were documented in accordance with the established protocol for five identified plants inside the designated plot. The phenological parameters, specifically the days to flower initiation, days to fifty percent blossoming, days to pod initiation and days to maturity, were recorded in a random manner within the plot and were expressed in terms of days.
 
Yield attributes and yield
 
Yield attributes were recorded from the five-plant sample collected at the time of harvest. The crop harvested from net plot area was converted into seed yield (kg/ha) and straw yield (kg/ha).
 
Moisture use indices
 
The temperature of soil is directly linked to the temperature of the atmosphere because soil is an insulator for heat flowing between the solid earth and the atmosphere.12 cm up from the tip of the soil thermometer was measured and the spot was marked and a hole was made. The soil thermometer was inserted through the spacer. 12 cm of the thermometer was sticking out of the bottom of the spacer and it was labelled to 10 cmand then then the soil temperature was measured.
 
Consumptive use of water was calculated by adding up the contribution of soil moisture and effective rainfall. Effective rainfall was measured by dividing the potential evapotranspiration by precipitation received (PET/P) (Dastane, 1974). Grain yield of chickpea was divided by the total consumptive use of water. To find out the moisture use efficiency.
 
Thermal indices
 
Following the method proposed by Monteith (1984), we tallied the daily mean temperature increments over the base temperature for the appropriate time intervals after sowing to determine the number of growing degree days for each phenological stage.
 

 

 
Where:
Tmax, Tmin= Maximum, minimum temperature.
T base= Base temperature taken as 5°C.
 
Helio thermal unit (HT)
 
Aids in evaluating crop responses to ambient temperature through phenological phases by effectively factoring in and expressing the effect of varying ambient temperature on the duration of the occurrences. Rajput’s formula from 1980 was used to determine the helio thermal unit.
 

HTU = GDD x Cumulative Sun Shine Hours (from sowing to physiological maturity)

 
Photothermal units (PTU)
 
PTU is calculated by multiplying cumulative growing degree days with day length that were obtained on a daily basis. Day length was estimated by calculating the sun rise and sun set (Dhaliwal et al., 2007).
 

PTU= GDD x Day length
 

Heat use efficiency was calculated as:

Growth parameters
 
Among the three dates of sowing, D₂ (5^th Dec) recorded the tallest plants (41.47 cm) which was significantly different from the rest two dates of sowing. The shortest plants were recorded in D₃ (15^th Dec) sowing (39.60 cm). Among the 5 moisture conservation practices, M₅ (Straw mulch@ 5t/ha +Seed priming with CaCl₂ solution @ 0.5% for 8 hours) recorded the tallest plants (43.98 cm) which were at par with M4 (Straw mulch@ 5 t/ha) (43.61 cm) and statistically superior to the rest of the treatments (Table 1).



Maximum number of primary and secondary branches were observed with chickpea sown on 25^th Nov (3.47 and 8.90) respectively, which was statistically superior to the other sowing dates. Among the nutrient management practices the maximum number of primary and secondary branches were recorded in M5, closely followed by M₄ and M₃.

The results revealed that delay in sowing of the chickpea crop significantly affected the days to flowering and to maturity. It was observed that the maturity date decreased with delay in sowing. Early sowing on 25^th November required a greater number of days to 50% flowering (41.8 days) and days to physiological maturity (101.1 days) of chickpea. The minimum days taken to 50% flowering (37.6 days) and days taken to physiological maturity (87.2 days) were recorded with 15^th December sowing. There is a reduction in the time taken to 50% flowering and time taken to physiological maturity due to the high temperature coinciding with the vegetative growth stage. Similar results were reported by Ali et al., (2018).

Among the moisture conservation practices the maximum number of days taken to 50% flowering (40.7 days) and days taken to physiological maturity (100.1 days) were recorded when straw mulch was applied @ 5t/ha +Seed priming of chickpea seeds was done with CaCl₂ solution @ 0.5% for 8 hours (M₅). This treatment was followed by treatments M₄ and M₃. The minimum days taken to 50% flowering (36.2 days) and days taken to physiological maturity (89.8 days) were recorded when no moisture conservation treatments were given (M₁).
 
Yield and yield attributes
 
Table 2 shows that as the planting date of chickpeas is pushed back, the plant yield, seed yield and grain yield all decline. Sowing on November 25^th resulted in the highest pod count per plant (43), seed count per pod (3.36) and grain yield (1832 kg/ha). A prolonged grain-filling period due to moderate temperatures during the grain-filling stage may account for the higher grain production of early seeded chickpeas (Rehman et al., 2015; Ray et al., 2020). The 15^th of December seeding produced the fewest pods per plant (37), seeds per pod (2.03) and grain yield (1401 kg/ha). A decrease in chickpea pods per plant, seeds per pod and grain output may result from delayed seeding if high temperatures occur during blooming and low temperatures occur during fertilization. The literature on this topic is extensive (Sharma and Sharma, 2002; Sethi et al., 2018; Kumar et al., 2021). Sowing on the 5^th of December resulted in the highest stover output (202 kg/ha), followed by sowing on the 25^th of November. Sowing on the 15^th of December resulted in the lowest stover production (155 kg/ha).

Among the moisture conservation practices, the treatments where straw mulch was applied gave better results than the other treatments. The maximum number of pods per plant (44) and number of seeds per pod (3.62), grain yield (1812 kg/ha) and straw yield (218 kg/ha) of chickpea was recorded with treatment M₅ (Straw mulch@ 5 t/ha +Seed priming with CaCl₂ solution @ 0.5% for 8 hours) which was at par with treatment M₄ (Straw mulch@ 5 t/ha). Treatment M₁(control) recorded the least values. Moisture present in the soil is the most important factor that influences the growth of chickpea plants right from the establishment of the seedling till its maturity. Therefore, moisture stress during the life cycle of the crop might be the reason for less yield in the controlled plot where no moisture conservation practices were adopted.

Interaction effects of sowing time and moisture conservation practices on number of pods per plant and number of seeds per pod were non-significant whereas it was significant with grain yield and straw yield of chickpea (Table 2).


 
Soil profile temperature
 
Among the three dates of sowing, there was no significant difference with regard to the soil profile temperature.

The soil profile temperature was increased significantly in the plots where the straw mulch was applied on the surface of the soil as a moisture conservation practice in comparison to the plots where only seed priming was done before sowing the seeds and the control plot (Table 3). The loss of heat from the soil profile to the atmosphere might have been prevented due to the application of straw mulch on the surface of the soil and also high moisture content might have been maintained in the soil which in turn helped in increasing the temperature of the soil during the winter season because of higher specific heat (Hari Ram et al., 2012). Similar results were reported by Choudhary et al., (2016).


 
Moisture use indices
 
Chickpea sown on third date i.e., on 15^th Dec recorded the maximum consumptive use of water (414.4 mm) and rate of moisture use (1.53 mm/day) followed by 5^th Dec sowing (208.7 mm and 1.49 mm/day) and 25^th Nov Sowing (204.2 mm and1.46 mm/day respectively). The moisture use efficiency was the maximum on the first date of sowing (12.44 kg/ha-mm) and was statistically superior to the rest of the two dates of sowing.

Among the moisture conservation practices the plots where straw mulch was applied recorded lesser values of consumptive use of water and rate of moisture use by chickpea in comparison to the rest of the plots. Treatment M₅ (Straw mulch@ 5 t/ha +Seed priming with CaCl₂ solution @ 0.5% for 8 hours) recorded the minimum consumptive use of water (203.5 mm) and rate of moisture use (1.36 mm/day) which was comparable to M4 (Straw mulch@ 5t/ha) (205.9 mm and 1.38 mm/day) and M₃ (Osmopriming-Seed priming with CaCl₂ solution @ 0.5% for 8 hours) (206.2 mm and 1.39 mm/day) respectively. Maximum consumptive use of water and rate of moisture use was recorded in the controlled plot (215.7 mm and 1.50 mm/day respectively).  Maximum moisture use efficiency was recorded in Treatment M₅ (12.34 kg/ha-mm) which was significantly superior to the rest of the moisture conservation practices. Treatment M₄ and M₃ closely followed treatment M₅. Moderate soil thermalregime and greater soil moisture retention under straw-applied treatments resulted in higher grain yield, thereby reducing the water use which in turn increased the water use efficiency and decreased the rate of moisture use (Mishra et al., 2012; Choudhary et al., 2016).
 
Thermal indices
 
Among the different sowing dates, the crop sown on 25th November recorded the maximum growing degree days (2113°C day), heliothermal unit (15081°C day hrs), photothermal unit (24177°C day hrs) and heat use efficiency (0.89 kg/ha/°C) to reach maturity followed by 5^th December sowing. Early sown crops require more heat units to reach maturity than late-sown crop (Suryakala et al., 2020). This might be due to longer crop duration of the crop recorded with early sowing and the incidence of higher temperature during the vegetative stage and moderate temperature during the grain filling stage of the crop. These findings are in conformity with those of Gan et al., (2002); Singh et al., (2008); Agrawal and Upadhyay, (2009) and Medida et al., (2020). Minimum growing degree days, heliothermal unit, photothermal unit and heat use efficiency was recorded with 15^th December sowing (1831°C day, 14263°C day hrs, 20881°C day hrs and 0.64 kg/ha/°C) respectively (Table 4). Late sown chickpeas accumulated fewer heat units as they were exposed to the suboptimal thermal regime which led to a decrease in heat use efficiency. These are in line with the findings of Agrawal et al., (2002); Agrawal and Upadhyay, (2009).



Among the different soil moisture conservation practices Treatment M₅ recorded the maximum growing degree days (2182°C day), heliothermal unit (15077°C day hrs), photothermal unit (22595°C day hrs) and heat use efficiency (0.94 kg/ha/°C) to reach maturity closely followed by treatment M₄. Treatment M₁(control) recorded the minimum heat units to reach maturity.

Based on the results of two years of experimentation it can be concluded that early sowing of chickpeas along with the application of straw mulch@ 5 t/ha + Seed priming with CaCl2 solution @0.5% for 8 hours is recommended for achieving higher productivity of chickpea crop in North Central Plateau Zone of Odisha.

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The authors declare no competing interests.