Physiology and Yield of Chickpea (Cicer arietinum L.) Genotypes in Response to Different Sowing Dates in Semi Arid Regions of North India 

Chickpea is the second most important legume crop after dry beans in the world with 14.5 million hectare area under cultivation and 14.7 million tonnes are produced annually with average seed yield of 1014 kg ha^-1 (FAOSTAT, 2020) whereas in India with 10.76 million hectare area under cultivation and 11.1 million tonnes produced with average seed yield of 1031 kg ha^-1 (Anonymous, 2019-20). In Haryana, it is grown over an area of 107,000 hectare with total production of 91,000 tonnes and productivity of 850 kg ha^-1 (Anonymous, 2019-20).
       
In India, Madhya Pradesh, Rajasthan, Maharashtra, Uttar Pradesh, Andhra Pradesh, Karnataka, Chhattisgarh, Bihar and Jharkhand are major chickpea cultivating and producing states contributing more than 95% to the total chickpea area and production. Madhya Pradesh is the single largest producer in the country accounting for over 41% of total production while Maharashtra, Rajasthan, Karnataka, Uttar Pradesh, Andhra Pradesh and Haryana contribute about 16, 13, 8, 6, 6 and 1.5% while area contribute about 34, 19, 17, 13, 6, 5 and 1.2% respectively. Sowing time is different for different varieties in a specific area and the optimum sowing time and highly productive cultivars can accelerate the growth, development and yield of the specific crop because sowing time can influence different climatic parameters, such as temperature, moisture, sunlight, etc. affecting plant growth (Bazvand et al., 2015). The high temperature at late sown condition may adversely affect the productivity of crops as both duration and grain filling stages are sensitive to alteration in temperature and also impact on morphological, physiological and biochemical behaviour of the crop (Moradshahi et al., 2004). High temperature can affect many physiological processes into plants like  photosynthesis, respiration, membrane stability and water status that results into increased concentrations of a variety of heat shock proteins (HSPs) and production of reactive oxygen species (Wahid and Close, 2007). However, during early sown conditions, temperature below 10°C is known to alter a variety of physiological processes ranging from plant water status, photosynthesis to reactive oxygen species (ROS) and  solute accumulation, excessive floral abortion and has adverse effect on chickpea yield and results in losses from 15-20% (Bakht et al., 2006; Chaturvedi et al., 2009). The present investigations was thus taken up to study the physiological and yield traits under different dates of sowing to screen out promising chickpea genotypes.

Hisar is located in North-West India at 215.2 meters above mean sea level with latitude of 29°10¢ North and longitude of 75°46¢ East. The minimum temperature in this area reaches upto 0.5°C in December and January and the maximum temperature in the area reaches upto 48°C during May or June. The mean weekly maximum temperature ranged between 16.9 to 39.3°C and minimum between 2.6 to 20.6°C, while, their corresponding values in 2018-19 were 17.1 to 40.7°C and 1.9 to 20.6°C respectively (Fig 1 and 2). Water potential (WP) of third leaves was measured with the help of Pressure Chamber. Osmotic potential (OP) was determined using psychrometric technique (Model 5100- B Vapor Pressure Osmometer). Calculation of (Relative water content) RWC (%) of leaves according to the formula given by Weatherley, (1950):
  Membrane injury index (RSI) was measured as percent proportion of ion leakage in to the external aqueous medium to the total ion concentration of the stressed tissue as measured by the EC of the external medium (Sullivan and Ross, 1979).  
Chlorophyll content was estimated according to the method of Hiscox and Israelstam (1979) using dimethyl sulfoxide (DMSO). Canopy temperature depression (CTD) measurements were made by using a handy Infra-red Thermometer (Model AG-42, Tele-temp Corp. CA). The number of branches emerging directly from the main stem counted at harvesting and average was recorded. The total number of pods obtained from five randomly selected plants was recorded and expressed as number of pods plant^-1. 100 seed were counted randomly from each genotypes and the test weight (g) was recorded. The completely matured plants were uprooted carefully along with roots and were dried completely. The weight of dried plant along with pods was recorded as biological yield (kg/ha). Harvest index is represented in terms of percentage.
   
Data were subjected to pooled analysis of both year (2017-18 and 2018-19) and analysis of (ANOVA) using Online Statistical Analysis Package (OPSTAT) Computer Section, CCS Haryana Agricultural University, Hisar.

Physiological parameters
 
The different parameters of plant water status i.e leaf water potential (yw), leaf osmotic potential (ys) and leaf relative water (RWC) content were affected by different dates of sowing. The water status of plant decides the rate of several physiological processes related to growth and development.  In the present investigation, among three dates of sowings, lowest leaf water potential (-0.35 Mpa), osmotic potential (-0.87 Mpa) and relative water content (61.5%) were recorded in 15^th December and highest (-0.30 Mpa, -0.71 Mpa, 88.5%, respectively) in November 15^th sowing (Table 1). This might be due to the reason that the high temperature (Max. temp. 28.9°C, Min. temp. 11.8°C) higher bright sunshine hours (7.2 h), more evaporation rate (4.0 mm/day) in 15 December sowing condition at 50% flowering stage that resulted into more transpiration rate while in 15th November sowing at 50% flowering stage the temperature (Max. temp. 22.2°C, Min. temp. 9.0°C), bright sunshine hours (5.6 h), evaporation rate (1.2 mm/day) were quite low as compared to 15^th December sowing that causes less transpiration rate that resulted into higher water potential, osmotic potential and RWC at 15^th November sowing. Similar results due to variation in temperature has also been reported earlier in the literature by (Singh et al., 2004; in chickpea, Sudhir et al., 2013 and Ram et al., 2015 in mustard). The data in Table 1 showed that highest values of leaf water potential, osmotic potential and relative water content in genotypes were recorded in genotype H12-64 and H13-01 whereas, minimum were in H14-04. These variation in genotypes is due their tolerance behaviour at low and high temperature condition and similar results also has been reported earlier in the literature by Singh et al., 2004; Sudhir et al., 2013; Ram et al., 2015).
 

       
The measurement of membrane injury is considered as a standard method for screening the material against stress tolerance and hence to study physiological response of chickpea at different sowing dates. The data in Table 1 showed that highest (11.26%) relative stress injury (RSI) was recorded in genotype H14-04 whereas, minimum relative stress injury (RSI) was in H13-01 (9.33%). These variation in genotypes is due their tolerance behaviour at low and high temperature condition. Similar results has also been reported earlier in the literature by Basu et al., 2011; Kumar et al., 2012 in chickpea. In the present investigation, among three dates of sowings, lowest (9.86%) relative stress injury (RSI) was recorded in crop sown on 15^th November and highest (11.03%) in December 15^th sowing. This might be due to the reason that the high temperature (Max. temp. 28.9°C, Min. temp. 11.8°C) in 15^th December sowing condition at 50% flowering stage that resulted into more leakage of ions while in 15^th November sowing at 50% flowering stage the temperature (Max. temp. 22.2°C, Min. temp. 9.0°C) was optimum as compared to 15^th December sowing that causes less leakage of ions so the increment of 6.7°C temperature in 15^th December sowing, resulted into more relative stress injury. Similar results has also been reported earlier in the literature by (Basu et al., 2011; Kumar et al., 2012 in chickpea; Mohammed and Tarpley, 2010 in rice; Kumar et al., 2011 in mungbean; Ram et al., 2012 in Indian mustard). Leaf temperatures are depressed below air temperature when the temperature above the optimal condition with water evaporates from their surface was noticed as canopy temperature depression (CTD). Among three dates of sowings, lowest (-2.20°C) canopy temperature depression was recorded in crop sown on 15^th December and  highest (-0.28°C) in November 15^th sowing. This might be due to variations in temperature (max 22.2 to 28.9°C and min 9.0 to 11.8°C), sunshine hours (5.6 to 7.2 hrs) at 50% flowering stages in 15^th November and 15^th December sowing dates respectively. These results are in agreement with the results obtained by Basu et al., 2011; Kumar et al., 2012 in chickpea; Basu et al., 2014 in wheat. The data in table 1 showed that highest (-0.50°C) canopy temperature depression in genotypes was recorded in genotype H13-01 whereas minimum canopy temperature depression was in H14-04 (-1.70°C). Similar results also documented earlier by Basu et al., 2011; Kumar et al., 2012 in chickpea. Chlorophyll content play an important role in photosynthetic activity. Due to higher chlorophyll content, light absorption rate and photosynthetic rate increases. The green plant pigments are thermo sensitive and their degradation occurs when subjected to higher temperature. In present investigation, decrease in chlorophyll was observed with delayed sowings beyond 15^th November (Table 1) Among three dates of sowings, lowest chlorophyll (3.516 mg g^-1 DW) was recorded in crop sown on 15^th December and highest (5.402 mg g^-1 DW) in November 15^th sowing at 50% flowering stage. This might be due to high temperature and low leaf area index at 50% flowering stage in 15^th December sowing as compared to 15^th November sowing. These results also in the same line as observed by Almeselmani et al., 2006; 2009 in wheat;  mungbean ; Kumar et al., 2011 in mungbean; Kaushal et al., 2011 in chickpea). Among genotypes, highest chlorophyll (5.027 mg g^-1DW) was recorded in genotype H13-01 whereas minimum (4.160 mg g^-1 DW) in H14-04. These variation in genotypes is due to differences in water status. Similar results also observed by (Kumar et al., 2011 in mungbean; Kaushal et al., 2011 in chickpea).
 
Yield and its attributes
 
Yield is a complex character which involves the interaction of several intrinsic and external factors. It largely depends upon the production and mobilization of carbohydrates, uptake of water and nutrients from the soil, in addition to several environmental factors to which plant is exposed during the growing period. The minimum seed yield (1889 kg/ha) and its attributes were observed in plants sown on 15^th December and maximum seed yield (2113 kg/ha) and its attributes were observed on 15^th October sowing and 15^th November (2090 kg/ha) sown crop (Table 2). This might be due to comparatively favorable climatic conditions such as plant water status, temperature, photoperiod, sunshine hours, photosynthetic rate and chlorophyll content in 15^th October and 15^th November sowing than 15^th December sowing. Lower seed yield during late sowing (15^th December) might be due to shorter grain filling period as a result of high temperature at grain filling stages and unfavourable conditions. Among genotypes, highest yield attributes and yield (2326 kg/ha) was recorded in genotype H13-01 and H12-64 (2255 kg/ha) whereas minimum (1594 kg/ha) in H14-04. This variation among genotypes might be due to differences in physiological traits that might be responsible for production potential. Similar result also reported earlier in the literature (Krishnamurthy et al., 2011; Mrudula et al., 2013; Pawar, 2015; Husnain et al., 2015; Sekhar et al., 2015; Patil et al., 2017; Ali et al., 2018; Bhasker et al., 2018; Meena et al., 2018 in clusterbean and Chaudhary et al., 2020 in Indian bean) due to different sowing dates.
 

Based upon various physiological traits and yield attributes, chickpea genotypes H12-64 and H13-01 were found to be promising in all the sowing dates and can be used in further breeding programme of chickpea for early (cold tolerance) and late (heat tolerance) sown conditions. It is concluded that these genotypes in future may prove better for late sown conditions (heat tolerance) and can be used in hybridization programme of chickpea. Maximum physiological parameters and seed yield were recorded between 15^th October and 15^th November sowing, however, further delay in sowing to 15th December, significant reduction in physiological parameters as well as seed yield were recorded.

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