Effect of sowing date and variety on morphological growth traits of rainfed groundnut

Introduction

Groundnut (Arachis hypogaea L.) is one of the world's most important oilseed crops, often referred to as the "king of vegetable oilseeds," "poor man's cashew nut" and "wonder nut" (Biswas and Bhattacharjee, 2019) [2] . The genus Arachis comprises over 70 wild species, but only A. hypogaea L. has been domesticated and is widely cultivated (Prasad et al., 2010) [3] . It is grown mainly between latitudes 40°N and 40°S, with a growth period of 90-115 days for sequential branching types and 120-140 days for alternate branching types. The crop thrives best at temperatures of 22-28°C, while yields may decline when temperatures fall below 18°C or rise above 33°C (FAO database). In India, groundnut covers an area of 4.71 million ha with 10.18 million tonnes production and 2163 kg ha -1 productivity. In Telangana, kharif area is 10 thousand ha with 28 thousand tonnes of production and 2832 kg ha -1 productivity while total area is 92 thousand ha with 225 thousand tonnes production and 2450 kg ha -1 productivity. (Indiastat, 2023-24). In India, its yield is majorly influenced by rainfall patterns, making it vulnerable to monsoon fluctuations and drought, with climate change further intensifying these challenges through unpredictable weather (Mukhtar et al., 2013) [4] . Consequently, productivity remains unstable. In Telangana, groundnut holds significant importance as an oilseed crop, primarily grown on red sandy loams and alfisols in districts such as Mahabubnagar, Nagarkurnool, Wanaparthy, Nalgonda, and Rangareddy. Despite its significance, the average yield remains limited to about 1.5-2.0 t ha⁻¹, constrained by erratic rainfall, low soil fertility, pest infestations and limited use of advanced farming practices (ICRISAT, 2023). Although many high-yielding groundnut varieties have been developed, their performance often varies with climatic conditions. Evaluating these varieties under local environments is essential, as temperature, rainfall and humidity play a crucial role in determining yield potential and disease tolerance (Soumya, 2011) [8] . Groundnut pod yield has been shown to follow a curvilinear trend in relation to rainfall and soil moisture availability (Bhatia et al., 2009) [6] making weather parameters as one of the major factors to be considered for groundnut production in Telangana. In Telangana, a baseline survey revealed that 98% of farmers rely on informal seed sources, with inadequate access to quality seed being a major constraint to improving yields and farm income (Charyulu et al., 2023) [7] . Research further indicates that, in many semi-arid regions, groundnut can deliver higher net returns and benefitcost ratios than alternative crops under favorable conditions (Nayak et al., 2021 and Kamble et al., 2023) [5,9] . Enhancing productivity during the kharif season in Telangana will require the adoption of improved varieties along with optimized sowing schedules.

Materials and Methods

The present investigation was conducted during the kharif, 2024 at the College Farm, College of Agriculture, Rajendranagar, Professor Jayashankar Telangana Agricultural University, Hyderabad (Telangana, India). The geographical location of the experimental site was 17° 19' 21" N latitude, 78° 24' 36" E longitude, with an elevation of 548 m above mean sea level. The experimental site is positioned in Telangana's Southern Telangana agro-climatic zone, falling under Troll's climate classification as a semi-arid tropic (SAT). According to the soil analysis results the soil was considered slightly alkaline in reaction and had a loamy texture. It was found to have a medium level of available phosphorus, a high level of available potassium, and a low level of organic carbon and available nitrogen. The research was conducted to study the impact of three sowing windows and five varieties. The three sowing dates under consideration were June II fortnight (June 20 th ), July I fortnight (July 5 th ) and July II fortnight (July 20 th ) and the varieties under study were TG37-A, KDG 128, TAG 24, TCGS 1694 and K6. The trail was conducted in Split-plot design with three replications, considering sowing dates as main plots and varieties as sub plots. Sowing was done accordingly and all the agronomic practices were followed as per the recommendation. Observations recorded from the investigation included days to emergence of seedling, days to attain physiological maturity, plant height (cm), leaf area (cm 2 ), leaf area index and leaf area duration at four phenological stages i.e., first flower bud appearance, 50% flowering, pod formation stage and physiological maturity.

Results and Discussion

Effect of sowing dates Days to emergence of the seedling Days to emergence of groundnut seedlings was significantly influenced by the dates of sowing as reported in Table 1. The crop sown on 20 th June 2024 (D 1 ) recorded the least number of days to emergence (9.4 days) while crop sown on 5 th July 2024 (D 2 ) recorded 9.7 days and 20 th July 2024 (D 3 ) sown crop required the maximum time for emergence (10.6 days) and was significantly higher than D 1 .The delay in emergence observed in D 3 could be attributed to lower bright sunshine hours (29 th Standard meteorological week) during late sowing, which might have affected seed germination and vigor. These results are consistent with previous findings that early sowing provides favorable conditions for rapid emergence by Caliskan et al. (2008) [10] .

Days to physiological maturity

Sowing dates variably affected growth parameters at different phenological stages as tabulated in Table 1. Dates of sowing did not significantly affect days to physiological maturity where D 2 (5 th July) matured fastest at 98.5 days, D 1 (20 th June) required 101.2 days and D 3 (20 th July) 104.9 days. These results were similar to findings of Kanade et al. (2015) [11] .

Plant height

The results regarding plant height as mentioned in Table 2 conclude that, at the first flower bud stage was not significantly influenced by the dates of sowing. Although statistically nonsignificant, the tallest plants were recorded in 5 th July sowing with a mean height of 16.05 cm, followed by 20 th June sowing (15.21 cm) and 20 th July sowing (15.07 cm). At the 50% flowering stage, dates of sowing did not significantly influence plant height. The highest mean plant height was recorded under D 3 with 23.39 cm, followed by D 2 (22.50 cm) and D 1 (21.27 cm). Similar findings were also reported by Gowda et al. (2017), who observed that delayed sowing enhanced stem elongation but did not translate to higher yields. At the pod formation stage, the effect of dates of sowing on plant height was found to be significant. The plants sown on 20 th June (D 1 ) attained a significantly greater height (35.39 cm) compared to those sown on 20 th July (D 3 , 32.43 cm), while D 2 (5 th July) was statistically on par with both. At physiological maturity, plant height was significantly influenced by sowing dates. The tallest plants were recorded in D 1 (41.77 cm), which was significantly superior to D 2 (35.91 cm) and statistically on par with D 3 (40.56 cm). The comparatively shorter plant height in the crop sown in July can be attributed to lower temperatures whereas the crop sown in June II fortnight has been exposed to comparatively higher temperatures that might have led to the rapid growth of the plants. These results are in line with the findings of Kamble et al. (2023) [9] . The findings were according to Reddy et al. (2014) [12] and Yadavrao et al. (2023) [13] Leaf area According to the statistical analysis of data related to leaf area as in Table 3, at 1 st flower bud appearance leaf area was found to be highest in D 1 with a mean value of 126.51 cm², followed by D 2 with 123.89 cm² and D 3 with 115.68 cm². Although D 1 recorded the highest leaf area, the differences among sowing dates were not statistically significant. A similar trend was observed at the 50% flowering stage with 418 cm 2 in D 1 sown crop 408.36 cm 2 in D 2 sown crop and 413.69 cm 2 in D 3 sown crop, where no significant difference was observed. During pod formation, leaf area remained statistically non-significant, indicating that sowing date had no significant effect on leaf area during this critical reproductive stage. However, the numerical values were in a decreasing trend with 1490.66 cm 2 in D 1 followed by 1487.15 cm 2 in D 2 and 1481.42 cm 2 in D 3 . At physiological maturity, a non-significant variation among sowing dates was recorded. These outcomes resonate with previous empirical results by Purna Chandana et al. (2025).

Leaf area index

The data encapsulated in Table 4, concludes that the sowing dates did not significantly influence LAI at any of the growth stages observed namely, first flower bud appearance, 50% flowering, pod formation and physiological maturity stages. However, numerically, D 1 (20 th June 2024) recorded the highest LAI at the early stages, i.e., 0.42 at first flower bud appearance and 1.40 at 50% flowering. This was followed closely by D 2 (5 th July 2024) and D 3 (20 th July 2024). During the pod formation stage, all three sowing dates exhibited comparable LAI values (4.94-4.97), indicating that plants across sowing dates developed a sufficient canopy during this key reproductive phase. At physiological maturity, D 2 showed slightly higher LAI (4.11) compared to D 1 and D 3 . Similar observations were recorded by Baliarsingh and Mahapatra (2015) [14] .

Leaf area duration

The LAD values across the three growth phases (1 st flower bud appearance to 50% flowering, 50% flowering to pod formation and pod formation to physiological maturity) did not differ significantly with sowing dates as per Table 5. However, D 3 (20 th July 2024) sown crop recorded the highest LAD of 126.9 days during pod formation to maturity, compared to 111.0 for D 1 (20 th June sown crop) and 100.3 for D 2 (5 th July sown crop). Though not statistically divergent, the elevated LAD for late sowing (D 3 ) may be attributed to cooler post-anthesis temperatures that delay senescence and extend leaf photosynthetic duration, resulting in prolonged green canopy retention. (Kingra and Kaur., 2012) [1] .

Effect of varieties Day to emergence of seedling

According to the data in Table 1, the difference in days to emergence among the varieties were not statistically significant, slight numerical variations were observed. TG 37-A and TAG 24 emerged in 9.5 days, KDG 128 in 9.7 days, TCGS 1694 in 10.5 days and K6 in 10.3 days. These variations are likely attributable to inherent varietal traits.

Days to physiological maturity

Varieties showed significant differences in days to attain maturity (Table 1). TAG 24 (90.8 days) and K6 (88.0 days) were earliest to mature while KDG 128 (110.5 days) and TCGS 1694 (110.6 days) took the longest time. This variation confirms that genetic differences primarily govern crop duration.

Plant height

A significant difference among varieties regarding plant height was observed at the 1 st flower bud appearance stage. Among the five tested varieties, K6 (V 5 ) recorded the highest plant height (17.74 cm) followed by TCGS 1694 (17.20 cm), whereas the shortest plants were observed in TAG 24 (13.04 cm). The difference in the plant height among different varieties can be attributed to the genetic differences among the varieties (Wang et al., 2021) [21] . At the 50% flowering stage, varietal differences remained significant. The tallest plants were recorded in K6 (23.93 cm), followed by TCGS 1694 (22.99 cm) and TAG 24 (21.22 cm). The shortest height was observed in TG 37-A (21.70 cm). During pod formation, the differences among varieties became more pronounced and statistically highly significant K6 (49.73 cm) exhibited an exceptionally high plant height, which was significantly superior to all other varieties. This was followed by TCGS 1694 (33.69 cm), TG 37 A (29.21 cm) and KDG 128 (28.94 cm). The lowest height at this stage was found in TAG 24 (27.34 cm). At the physiological maturity stage, a significant variation was recorded among the varieties. K6 showed significantly maximum plant height of 52.79 cm followed by TCGS 1694 (37.64 cm), KDG 128 (36.50 cm) and TG37 A(6.46 cm). TAG 24 continued to show the lowest plant height (33.69 cm), indicating its dwarf nature. The consistent superiority of K6 throughout the growth stages may be attributed to its higher photosynthetic activity and better partitioning of assimilates towards vegetative organs. Similar results were registered by Swetha Sree et al. (2020) [15] . The data for those arranged in Table 2.

Leaf area

The data of effect of sowing dates and varieties on leaf area has been presented in Table 3.TAG 37-A (134.55 cm²) and KDG 128 (132.33 cm²) recorded significantly higher leaf area compared to TAG 24 (120.78 cm 2 ), K6 (116.22 cm 2 ) and TCGS 1694 (106.27 cm²) at the 1 st flower bud appearance stage. TG37-A exhibited the highest leaf area (439.10 cm²), significantly superior than K6 (400.80 cm 2 ) and TCGS 1694 (389.73 cm 2 ) and significantly on par to TAG 24 (419.50 cm²) and KDG 128 (418.73 cm²) during the 50% flowering stage. The marked increase in leaf area can be linked to accelerated cell division and expansion, coupled with vigorous vegetative growth supported by favorable weather conditions such as optimal temperature, adequate rainfall and sufficient light during the growth period. These outcomes resonate with previous empirical results by Banik et al. (2009) [17] . Although the differences at the pod formation stage were not statistically significant, the recorded leaf area values were TAG 24 (1521.80 cm²), TCGS 1694 (1517.84 cm²), TG 37-A (1481.81 cm²), K6 (1457.93 cm²) and KDG 128 (1452.66 cm²). These values reflect the genetic capacity of the varieties to optimize source area during this crucial reproductive stage. Similar observations were reported by Mohite et al. (2017) [16] and Ragavalli et al. (2019) [18] . TG 37A (1257.19 cm²) and TAG 24 (1242.15 cm²) exhibited substantially larger leaf areas at physiological maturity than TAG 24 (1150.99 cm²). These findings were consistent with the findings reported by Vaishnavi.

Leaf area index

The effect of sowing dates and five varieties is presented in Table 4. Groundnut leaf area index was significantly impacted by the types in the first stage of flower bud appearance. The variety TG 37A (0.45) had a much greater leaf area index than the other types, TAG 24 (0.40) and K-6 (0.39) (0.42), and was in line to KDG 128 (0.44). TCGS-1694 had the significantly lowest leaf area index (0.33). At 50% flowering stage, there was significant effect of varieties on leaf area index of groundnut. Significantly higher leaf area index was recorded in the variety TG 37A (1.46) than the varieties KDG 128 (1.40) which was on par with TAG 24 (1.40) and significantly higher than K6 (1.34) and TCGS 1694 (1.30). At pod formation stage there was no significant effect of varieties on the leaf area index of the groundnut. Similarly, at physiological maturity stage higher leaf area index was reported in TG 37A (4.19) variety which was on par to TAG 24 (4.14) and significantly higher than KDG 128 (4.00), K6 (3.95) and TCGS 1694(3.90). The observed varietal differences can be linked to genetic diversity in canopy architecture, leaf retention capacity, and growth period. According to Deshmukh et al. (2020) [19] , KDG 128 is characterized by its ability to sustain a higher leaf area index under rainfed and terminal stress conditions, whereas TG 37-A is noted for its pronounced early growth vigor.

Leaf area duration

The observations on LAD as influenced by dates of sowing and varieties are presented in Table 5. Varietal differences had a statistically significant influence on LAD during the interval from 50% flowering to pod formation. TG 37-A (V 1 ) and KDG 128 (V 2 ) recorded LAD values of 93 days while TAG 24(60.1 days), TCGS 1694(84.8 days) and K6(46.2 days). In the period from pod formation to physiological maturity, KDG 128 (132.8) was significantly higher than TAG 24, TCGS 1694, and K6, and comparable to TG 37-A (129.3). Both of these varieties also outperformed those with lower LAD. These trends may be associated with differences in canopy persistence, leaf senescence rate, and photosynthetic capacity. Varieties such as TG 37-A and KDG 128 tend to retain green leaf area for a longer duration during seed filling, thereby supporting greater assimilate production and improved yield potential (Meena et al., 2015) [20] . The sowing date × variety interaction remained non-significant at all stages.

Conclusion

In groundnut, plant height was not significantly influenced by sowing dates at the first flower bud and 50% flowering stages, but the effect became significant during pod formation and physiological maturity. Across varieties, significant differences in plant height were recorded at all growth stages, with K6 attaining the greatest height at physiological maturity, surpassing TCGS 1694, KDG 128, TAG 24 and TG 37A. Sowing dates did not significantly impact leaf area, leaf area index (LAI) and leaf area duration (LAD). However, varietal differences were evident for leaf area. TG 37-A exhibited a significantly larger leaf area than TCGS 1694 and K6, while being comparable to TAG 24 and KDG 128. At physiological maturity, TG 37A also recorded a significantly higher LAI than TCGS 1694 and K6, but was statistically similar to KDG 128 and TAG 24. For LAD, KDG 128 recorded significantly higher values than TAG 24 and K6, while remaining at par with TCGS 1694 and TG 37-A.

References

1. Kingra PK, Kaur P. Effect of dates of sowing on thermal utilisation and heat use efficiency of groundnut cultivars in central Punjab. Journal of Agricultural Physics. 2012;12(1):54-62.
2. Biswas S, Bhattacharjee S. Groundnut: Multifarious utilities of the 'King of Oilseeds'. Agriculture & Food: ENewsletter. 2019;1:373.
3. Prasad PV, Kakani VG, Upadhyaya HD. Growth and production of groundnut. UNESCO Encyclopedia. 2010. p. 1-26.
4. Mukhtar AA, Babaji BA, Ibrahim S, Mani H, Mohammad AA, Ibrahim A. Dry matter production and harvest index of groundnut (Arachis hypogaea L.) varieties under irrigation. Journal of Agricultural Science. 2013;5(8):153.
5. Nayak A, Lokesha H, Gracy CP. Growth and instability analysis of groundnut production in India and Karnataka. Journal of Oilseeds Research. 2021;38(1):72-80.
6. Bhatia VS, Singh P, Kesava Rao AVR, Srinivas K, Wani SP. Analysis of water non-limiting and water limiting yields and yield gaps of groundnut in India using CROPGRO-Peanut Model. Journal of Agronomy and Crop Science. 2009;195(6):455-63.
7. Charyulu DK, Reddy DS, Reddy VR, Mamatha K, Govardhan M, Gajanan S, et al. Groundnut value chain innovations to enhance farmer profitability and promote oil, food and confectionery industries in Telangana. Mapping Groundnut Technologies in Telangana (Baseline Survey) Report, Research Bulletin No. 29. 2023.
8. Acharya N.G. Ranga Agricultural University; 2011.
9. Kamble DJ, Pacharne DP, Danawale NJ, Deshmukh PH, More SR, Patil MR. Response of groundnut (Arachis hypogaea L.) cultivars to sowing dates under summer season. Pharmaceutical Innovation Journal. 2023;12(8):2705-8.
10. Caliskan S, Caliskan ME, Arslan M, Arioglu H. Effects of sowing date and growth duration on growth and yield of groundnut in a Mediterranean-type environment in Turkey. Field Crops Research. 2008;105(1-2):131-40.
11. Kanade SG, Shaikh AA, Jadhav JD. Effect of sowing dates in groundnut (Arachis hypogea L.) on growth, yield attributing characters and yield. Advance Research Journal of Crop Improvement. 2015;6(1):5-11.
12. Yadavrao WS, Bhambhar KS, Satish MS, Dadaji JJ, Shaikh AA, Atmaram SV. Thermal indices requirement of kharif groundnut (Arachis hypogaea L.) varieties under different sowing window in western Maharashtra, India. International Journal of Environment and Climate Change. 2023;13(8):265-277.
13. Baliarsingh A, Mahapatra PK. Effect of date of sowing and moisture regime on growth and yield of summer groundnut (Arachis hypogaea L.). Indian Journal of Agronomy. 2015;60(2):260-4.
14. Sree MS, Sudhakar P, Mahesh VU, Prathima T, Krishna GT. Physiological Responses of Variable Growth Habit Groundnut (Arachis hypogea L.) Genotypes at Different Planting Densities. International Journal of Current Microbiology and Applied Sciences. 2020;9(6):3717-25.
15. Mahatma Phule Krishi Vidyapeeth, Rahuri, India; 2017.
16. Banik CN, Nath R, Chakraborty PK. Effect of dates of sowing on growth and yield of groundnut crop. Journal of Crop and Weed. 2009;5(2):59-62.
17. Raagavalli K, Soumya TM, Veeranna HK, Nataraju SP, Narayanswamy H. Effect of sowing windows on growth and yield of groundnut (Arachis hypogaea L.) genotypes. Journal of Oilseeds Research. 2019;36(1):20-23.
18. Deshmukh PS, Bhale VM, Bhaskar PS, Bhoge VD. Evaluation of groundnut genotypes for yield and yield-attributing traits under rainfed condition. International Journal of Chemical Studies. 2021;9(4):1382-5.
19. Meena RS, Yadav RS, Reager ML, De N, Meena VS, Verma JP, et al. Temperature use efficiency and yield of groundnut varieties in response to sowing dates and fertility levels in western dry zone of India. Journal of Oilseeds Research. 2015;32(1):49-51.
20. Wang J, Yan C, Shi D, Zhao X, Yuan C, Sun Q, et al. The genetic base for peanut height-related traits revealed by a meta-analysis. Plants. 2021;10(6):1058.