Effect of high temperature and nitrogen stress on growth attributes of rice cultivars

Introduction

Rice (Oryza sativa L.) is the most important and extensively cultivated food crop that has been referred as "Global Grain" because of its use as prime staple food in about 100 countries of the world. Its cultivation is of immense importance to food security of Asia, where more than 90% of the global rice is produced and consumed. Rice provides 32-59% of the dietary energy and 25-44% of the dietary protein in 39 countries. In India, it accounts for more than 40% of food grain production, providing direct employment to 70% people in rural areas (Anon., 2020) [1] . Over 2 billion people in Asia alone derive 80 per cent of their energy needs from rice, which contains 80 percent carbohydrates, 7-8 per cent protein, 3 per cent fat, and 3 per cent fiber, which constitutes the principle food for about 60 per cent of the world's population. Globally, rice demand is expected to increase by 25% from the year 2001 to 2025 to meet the requirement of increasing population. Globally, total rice area is about 165.62 M ha, production is 520.90 Mt with productivity of 3.1 t ha -1 (Anonymous, 2023a) [2] . In India, increase in minimum support price of rice and its adaptability to various biotic and abiotic factors have made it a preferable crop for farmers especially those who fall under the category of marginal farmers. In India it is cultivated area in nearly 46.51 million ha with production of about 130.29 million tonnes and average productivity of 2809 kg/ha (Anonymous, 2023b) [3] . Rice plays a vital role in our food as well as nutritional security for millions of livelihood. Thus, the slogan "Rice is life" by IRRI during 2004 seems to be most appropriate (Chandrasekaran et al., 2007) [6] . Rice ranks second to wheat in terms of area harvested but in terms of importance as a food crop, rice provides more calories ha -1 than any cereal crop. Besides its importance as food, rice provides. Nutrients are one of the most important inputs, required by the plants for their growth and yield. The N, P and K are major nutrients and are supplied through fertilizers and manures. At present, increasing cost of fertilizers, growing ecological 2 concern and conservation of energy have created considerable interest for the use of organics as a source of plant nutrients with blending of chemical fertilizer to reduce losses of nutrients as integrated nutrient management system (Verma et al., 2017) [18] .

Materials and Methods

Study Site and Experimental Design

The field experiments were conducted at the MB-4C farm facility at IARI Farm (Latitude: 28°4'N, Longitude: 77°09'E, Altitude: 228.16 m above MSL) on rice crops during the years 2019-20 and 2020-21. The study utilized a randomized block design with six treatments, each having three replications. The treatments included two nitrogen levels (N 1 -recommended nitrogen dose of 120 kg/ha, and N 0 -no nitrogen application) and six rice varieties: Basmati 370 (V 1 ), Jaldi Dhan-13 (V 2 ), Jaldi Dhan-6 (V 3 ), Pusa Basmati-1 (V 4 ), Annapurna (V 5 ), and Nagina-22 (V 6 ). Each experimental plot had a specified area, and standard agronomic practices, including irrigation, pest management, and fertilization, were followed as per local recommendations. Data were collected for photosynthetic rate (mmol m⁻² s⁻¹) at various growth stages: tillering, panicle initiation, booting, flowering, and ripening. The photosynthetic rate was measured using a portable photosynthesis measurement system at different growth stages during both years. The data were recorded for each treatment at specific intervals during the growing season, with significant maximum and minimum values for photosynthetic rate observed in different treatments. Chlorophyll content (Chl a + b) was also measured at several days after transplanting (DAT) intervals: 10, 17, 24, 31, 38, 45, 52, 59, 66, 73, and 80 DAT. Chlorophyll measurements were taken using a chlorophyll meter, and the results were analyzed for significant differences across treatments. Statistical analysis of the data was performed using analysis of variance (ANOVA) to assess the significant differences between the treatments, and means were compared using the randomized block design at a significance level of p ≤ 0.05.

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (9.32), which was at par with the treatment, N 1 V 5 (9.32) and N 1 V 5 (9.08). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (6.40) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (10.27), which was at par with the treatment, N 1 V 5 (10.25) and N 1 V 5 (10.02). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (7.35) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (9.80), which was at par with the treatment, N 1 V 5 (9.78) and N 1 V 5 (9.55). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (6.88) in the pooled mean.

Panicle initiation

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (12.17 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 5 (11.26 mmol m -2 s -1 ) and N 1 V 4 (11.77 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (8.58 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (12.70 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 5 (11.54 mmol m -2 s -1 ) and N 1 V 4 (12.32 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s - 1 ) was seen in treatment N 0 V 2 (9.12 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (12.44 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 5 (11.54 mmol m -2 s -1 ) and N 1 V 4 (12.04 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (8.85 mmol m -2 s -1 ) in the pooled mean.

Booting

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (16.95 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (15.65 mmol m -2 s -1 ) and N 1 V 6 (15.61 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (11.63 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (17.71 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (16.60 mmol m -2 s -1 ) and N 1 V 6 (16.36 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (12.00 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (17.33 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (16.13 mmol m -2 s -1 ) and N 1 V 6 (15.99 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (11.81 mmol m -2 s -1 ) in the pooled mean.

Flowering

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (23.20 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (23.19 mmol m -2 s -1 ) and N 1 V 6 (21.59 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (14.90 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (24.00 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (23.99 mmol m -2 s -1 ) and N 1 V 6 (22.39 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (15.70 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 4 (23.60 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (23.59 mmol m -2 s -1 ) and N 1 V 6 (21.99 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (15.30 mmol m -2 s -1 ) in the pooled mean.

Ripening

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 2 (4.12 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 4 (4.10 mmol m -2 s -1 ) and N 1 V 6 (4.04 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (2.38 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 2 (4.16 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 4 (4.15 mmol m -2 s -1 ) and N 1 V 6 (4.09 mmol m -2 s - 1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (2.42 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 2 (4.14 mmol m -2 s - 1 ), which was at par with the treatment, N 1 V 4 (4.12 mmol m -2 s -1 ) and N 1 V 6 (4.06 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (2.40 mmol m -2 s -1 ) in the pooled mean.

TGT Tillering

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (9.10 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 6 (8.89 mmol m -2 s -1 ) and N 1 V 5 (8.65 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (5.68 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (9.66 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 6 (9.41 mmol m -2 s -1 ) and N 1 V 5 (9.19 mmol m -2 s - 1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (6.21 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (9.38 mmol m -2 s - 1 ), which was at par with the treatment, N 0 V 6 (9.15 mmol m -2 s -1 ) and N 1 V 5 (8.92 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (5.95 mmol m -2 s -1 ) in the pooled mean.

Panicle initiation

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (11.57 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 6 (10.80 mmol m -2 s -1 ) and N 1 V 5 (11.30 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (6.89 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (12.32 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 6 (11.54 mmol m -2 s -1 ) and N 1 V 5 (12.04 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s - 1 ) was seen in treatment N 0 V 2 (7.62 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (11.95 mmol m -2 s -1 ), which was at par with the treatment, N 0 V 6 (11.17 mmol m -2 s -1 ) and N 1 V 5 (11.67 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (7.25 mmol m -2 s -1 ) in the pooled mean.

Booting

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (14.69 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (13.57 mmol m -2 s -1 ) and N 1 V 4 (14.63 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 3 (9.06 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (15.29 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (14.17 mmol m -2 s -1 ) and N 1 V 4 (15.23 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s - 1 ) was seen in treatment N 0 V 3 (8.66 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (14.99 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (13.87 mmol m -2 s -1 ) and N 1 V 4 (14.93 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 3 (8.86 mmol m -2 s -1 ) in the pooled mean.

Flowering

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (19.79 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 1 (17.09 mmol m -2 s -1 ) and N 1 V 4 (17.50 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 3 (9.57 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (20.29 mmol m -2 s -1 ), which was followed by the treatment, N 1 V 1 (17.59 mmol m -2 s -1 ) and N 1 V 4 (18.00 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s - 1 ) was seen in treatment N 0 V 2 (9.46 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (20.04 mmol m -2 s -1 ), which was followed by the treatment, N 1 V 1 (17.34 mmol m -2 s -1 ) and N 1 V 4 (17.75 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 2 (9.71 mmol m -2 s -1 ) in the pooled mean.

Ripening

The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (3.69 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 2 (3.28 mmol m -2 s -1 ) and N 1 V 4 (3.18 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (1.20 mmol m -2 s -1 ) in the year 2019-20. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (3.73 mmol m -2 s -1 ), which was at par with the treatment, N 1 V 2 (3.32 mmol m -2 s -1 ) and N 1 V 4 (3.23 mmol m -2 s - 1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (1.25 mmol m -2 s -1 ) in the year 2020-21. The observations about photosynthetic rate (mmol m -2 s -1 ) was significantly maximum in treatment N 1 V 6 (3.71 mmol m -2 s - 1 ), which was at par with the treatment, N 1 V 2 (3.30 mmol m -2 s -1 ) and N 1 V 4 (3.20 mmol m -2 s -1 ). The significantly minimum photosynthetic rate (mmol m -2 s -1 ) was seen in treatment N 0 V 1 (1.22 mmol m -2 s -1 ) in the pooled mean.

Chlrophyll content (chl a+b) Ambient

The data regarding on chlrophyll content (chl a+b) at 10 DAT significantly maximum in the treatment N 1 V 3 with value (1.12), which was at par with the treatment N 1 V 2 and N 1 V 6 with measuring (1.11) and (1.11). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (0.92) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 10 DAT significantly maximum in the treatment N 1 V 3 with value (1.18), which was at par with the treatment N 1 V 2 and N 1 V 6 with measuring (1.16) and (1.17). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (0.97) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 10 DAT significantly maximum in the treatment N 1 V 3 with value (1.15), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (1.14) and (1.15). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (0.95) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 17 DAT significantly maximum in the treatment N 1 V 3 with value (1.31), which was at par with the treatment N 1 V 2 and N 1 V 6 with measuring (1.30) and (1.29). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.02) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 17 DAT significantly maximum in the treatment N 1 V 3 with value (1.37), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (1.35) and (1.35). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.07) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 17 DAT significantly maximum in the treatment N 1 V 3 with value (1.34), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (1.32) and (1.32). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.05) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 24 DAT significantly maximum in the treatment N 1 V 3 with value (1.44), which was at par with the treatment N 1 V 2 and N 1 V 6 with measuring (1.42) and (1.44). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.08) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 24 DAT significantly maximum in the treatment N 1 V 6 with value (1.51), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (1.46) and (1.49). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.11) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 24 DAT significantly maximum in the treatment N 1 V 6 with value (1.48), which was at par with the treatment N 1 V 3 and N 1 V 6 with measuring (1.47) and (1.48). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.09) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 31 DAT significantly maximum in the treatment N 1 V 6 with value (2.45), which was at par with the treatment N 1 V 2 and N 1 V 6 with measuring (2.38) and (2.45). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.35) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 31 DAT significantly maximum in the treatment N 1 V 6 with value (2.51), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (2.41) and (2.47). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 3 (1.00) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 31 DAT significantly maximum in the treatment N 1 V 6 with value (2.48), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (2.39) and (2.45). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.36) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 38 DAT significantly maximum in the treatment N 1 V 6 with value (2.74), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (2.67) and (2.70). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.47) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 38 DAT significantly maximum in the treatment N 1 V 6 with value (2.79), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (2.73) and (2.76). While significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.51) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 38 DAT significantly maximum in the treatment N 1 V 6 with value (2.76), which was at par with the treatment N 1 V 2 and N 1 V 3 with measuring (2.70) and (2.73). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 1 V 1 (1.49) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 45 DAT significantly maximum in the treatment N 1 V 6 with value (3.30), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (3.18) and (3.22). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.62) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 45 DAT significantly maximum in the treatment N 1 V 6 with value (3.36), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (3.23) and (3.28). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.65) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 45 DAT significantly maximum in the treatment N 1 V 6 with value (3.33), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (3.20) and (3.25). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.63) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 52 DAT significantly maximum in the treatment N 1 V 6 with value (2.79), which was at par with the treatment N 1 V 4 and N 1 V 5 with measuring (2.79) and (2.93). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (1.99) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 52 DAT significantly maximum in the treatment N 1 V 6 with value (2.83), which was at par with the treatment N 1 V 4 and N 1 V 5 with measuring (2.82) and (2.96). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (2.03) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 52 DAT significantly maximum in the treatment N 1 V 6 with value (2.81), which was at par with the treatment N 1 V 2 and N 1 V 5 with measuring (2.88) and (2.95). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 1 (2.01) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 59 DAT significantly maximum in the treatment N 1 V 4 with value (3.15), which was at par with the treatment N 0 V 4 and N 1 V 1 with measuring (2.76) and (2.83). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 2 (1.81) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 59 DAT significantly maximum in the treatment N 1 V 4 with value (3.21), which was at par with the treatment N 0 V 4 and N 1 V 1 with measuring (2.79) and (2.89). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 3 (1.80) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 59 DAT significantly maximum in the treatment N 1 V 4 with value (3.18), which was followed by the treatment N 0 V 4 and N 1 V 1 with measuring (2.77) and (2.86). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 2 (1.83) in the pooled mean. The data regarding on chlrophyll content (chl a+b) at 66 DAT significantly maximum in the treatment N 1 V 1 with value (3.75), which was followed by the treatment N 0 V 1 and N 1 V 4 with measuring (2.71) and (2.75). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 5 (1.61) in the year 2019-20. The data regarding on chlrophyll content (chl a+b) at 66 DAT significantly maximum in the treatment N 1 V 1 with value (3.82), which was followed by the treatment N 0 V 1 and N 1 V 4 with measuring (2.78) and (2.79). While the significantly minimum chlrophyll content (chl a+b) was seen in the treatment N 0 V 3 (1.67) in the year 2020-21. The data regarding on chlrophyll content (chl a+b) at 66 DAT significantly maximum in the treatment N 1 V 1 with value (3.79), which was followed by the treatment N 0 V 1 and N 1 V 4 with measuring (2.74) and (2.77). While the significantly minimum

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