Phenological responses of soybean (Glycine max L.) to different sowing dates during the off-season in Northern Telangana zone

Introduction

Soybean is recognized as the "Golden bean" of the 21 st century. The demand for soybean is raising globally due to its inimitable composition, outstanding dietetic value and health benefits (Khan et al., 2020) [6] . It occupied a prominent position among the legumes that supplement nearly one-third of the world population. India is the 5 th largest soybean producer after Brazil (34.45%), U.S.A. (29.01%), Argentina (16.56%), and China (4.00%). In India, soybean produced over an area of 121.5 lakh hectares with a production of 129.9 lakh tones and productivity of 1069 kg ha -1 (Indiastat, 2021) [3] . The major soybean growing states in India are Madhya Pradesh, Maharashtra, Rajasthan, Karnataka and Telangana. In Telangana, soybean produced over an area of 1.55 lakh hectares with a production of 2.68 lakh tonnes and productivity of 1731 kg ha -1 (Indiastat, 2021) [3] . Though the soybean crop has immense opportunity in global market, yields are extremely less than its potential yield in Telangana. In Telangana, the soybean crop is cultivated during kharif season. The main factors that reduce its yields are climate unevenness, in appropriate growing time, lower germination percentage, meager quality and scarcity of seed. Further the viability and longevity of soybean seeds very low. Therefore, there is a less opportunity to store the seeds produced during kharif for the next kharif season. It is inevitable to import the seed from distance places like north India every season which is much expensive for the farmers of Telangana. If the crop produced during rabi or summer (off season), the seeds can be used for next kharif so that, the additional cost incurred on cold storage and transport can be minimized. No documented results are available on soybean cultivation during the off-season for either grain or seed purposes. The suitable planting date of soybean is probably the most conspicuous cultural practice for maximizing seed yield during the off-season. Different varieties of soybean are sensitive to changes in environmental conditions where the crop is being grown. Therefore, it is necessary to study the genotype × environment interactions to identify the varieties which are stable in different environments (Calvino et al., 2003) [1] . Keeping in view of the poor germination, shortage of seed availability in soybean, arising opportunity for alternate crops to rabi rice, increase in irrigation potential, and variable climatic conditions in Telangana, the present investigation is prioritized to identify the optimum time of sowing and suitable cultivars for growth of soybean during the off-season in Northern Telanagana zone.

Materials and Methods

A field experiment was conducted during off-season 2022-23 at Regional Sugarcane & Rice Research Station, Rudrur, Nizamabad. Which is geographically located at 18 o .56 " N latitude and 77 o .87 " E longitude, at an altitude of 404 m above the mean sea level situated in Northern climatic zone of Telangana. The soil of experimental field was clay loam in texture, low in available nitrogen (120 kg ha -1 ) and organic carbon content (0.38%), and high in available phosphorus (42.08 kg ha -1 ) and potassium (285.2 kg ha -1 ),). The experiment was laid out in strip plot design with twenty seven treatments, comprising of three varieties viz., JS 335 (V 1 ), ASB 22 (V 2 ) and KDS 726 (V 3 ) as horizontal strips and nine dates of sowings viz., 3 Oct (D 1 ), 19 Oct (D 2 ), 3 Nov (D 3 ), 19 Nov (D 4 ), 3 Dec (D 5 ) 19 Dec (D 6 ), 3 Jan (D 7 ), 19 Jan (D 8 ) and 3 Feb (D 9 ) as vertical strips, replicated thrice. A seed rate of 75 kg ha -1 was used for sowing. The spacing adopted was 45 cm × 5 cm sown at a depth of 3-4 cm. Seeds were treated with Carbendazim @ 1 g kg -1 of seed to protect crop against seed borne diseases. Recommended dose of 60-60-40 (N -P 2 O 5 -K 2 O) kg ha -1 was applied to soybean crop, in the form of urea, single super phosphate and muriate of potash, respectively to all the plots. Total quantity of phosphorous and potassium was applied as basal whereas nitrogen was applied in two equal splits, one at the time of sowing and another at 30 days after sowing. The crop was irrigated at an interval of 7 to 10 days depends up on visual moisture stress symptoms exhibited by the crop canopy. Standard recommended package of practice of kharif season suggested by PJTSAU was followed. The number of days taken to emergence of 50% seedlings, bud appearance, 1 st flower appearance, 1 st pod appearance, 1 st pod dry and 75% of pods dry stages was counted based on morpho physiological appearance of 50% plants in net plot area and expressed in days and analyzed statistically using OP Stat.

The duration of emergence of soybean cultivars and their interaction with dates of sowing did not differ significantly (Table 1). This result indicates that, the speed of germination and emergence of soybean cultivars was not sensitive to the variable set of weather conditions prevailed during this phase under different dates of sowings.

Days to buds appearance stage

The days to attain bud appearance stage was influenced by the interaction effects of varieties and sowing dates (Table 1). In 19 Oct (D 2 ) sowing, the cv. KDS 726 (V 3 ) took 34 days to attain bud appearance stage which was significantly more than the cv. JS 335 (31 days) and cv. ASB 22 (30 days). However, the days to bud appearance of cultivars JS 335 (31 days) and ASB 22 (30 days) were comparable to each other. Similar trend was also reflected in D 4 , D 6 , D 8 and D 9 sowing dates. Whereas, in 3 Nov sowing, the days to bud appearance of cv. KDS 726 (34 days) was comparable with cv. ASB 22 (32 days) and significantly more over cv. JS 335 (30 days). Further, in 3 Dec sowing the more number of days to bud appearance was observed in cv. KDS 726 (33 days) which was comparable with cv. JS 335 (31 days) and significantly more over cv. ASB 22 (30 days). But in 3 Oct and 3 Jan sown crops no significant variation in days to bud appearance stage was noticed among the cultivars. The more number of days to attain bud appearance was registered by the cv. KDS 726 across the sowing dates over cv. JS 335 (V 1 ) and cv. ASB 22 (V 2 ) might be due to its inherent genetical property. These results are in accordance to the findings of Gochar et al. (2022) [2] . The individual varietal performance under different dates of sowing showed that, the cv. JS 335 (V 1 ) required 39 days to attain bud appearance when it was sown on 3 Oct (D 1 ) which was significantly longer than all its succeeding dates sowings. But, when it was sown on 19 Nov (D 4 ) required only 28 days to reach bud appearance stage. However, it was at par with D 2, D 3, D 5, D 6, D 7 and D 8 date sowings. The more number of days (39 days) to reach bud appearance of cv. ASB 22 (V 2 ) was observed in 3 Oct (D 1 ) sown crop which was significantly more than the all other sowing dates. The shorter span of 28 days to attain bud appearance was observed in 19 Dec (D 6 ) date sown crop. However, it was comparable with D 2 , D 4, D 5, D 7, D 8 and D 9 dates sown crops. The maximum number of days (40 days) to attain bud appearance of cv. KDS 726 was observed in 3 Oct (D 1 ) sown crop which was significantly more than the all other sowing dates. The minimum number of days (30 days) to reach bud appearance was noticed with the crop sown on 3 Jan (D 7 ). However, it was comparable with D 5 and D 6 date sown crops. The reduced photoperiod or shorter day length with huge difference in maximum and minimum temperatures restricted the vegetative growth and triggered the reproductive phase very quickly resulting in early completion of vegetative phase (Oad et al., 2002) [7] . Similar results were also demonstrated by Khan et al. (2003) [5] .

Days to 1 st flower appearance stage

The days to attain this stage was influenced by interaction effect of varieties and sowing dates (Table 1). The cv. KDS 726 (V 3 ) sown on 3 Nov (D 3 ) took significantly maximum number of days (47 days) to reach 1 st flower appearance stage which was 11 and 8 days more over cv. JS 335 (11 days) and cv. ASB 22 (8 days), respectively. This trend was also reflected in its preceding D 2 and succeeding D 4, D 6, D 7 and D 8 dates sown crops. Further, in 3 Oct and 3 Dec sown crops there was no significant variation among the cultivars was noticed in days to 1 st flower appearance stage. The more number of days to attain 1 st flower appearance stage registered by the cv. KDS 726 across the sowing dates over cv. JS 335 (V 1 ) and cv. ASB 22 (V 2 ) might be due to its inherent genetical property. Individual varietal performance under different dates of sowing showed that, the cv. JS 335 (V 1 ) has taken more number of days (42 days) to attain 1 st flower appearance stage in 3 Oct (D 1 ) sowing which was comparable with D 5, D 8 and D 9 and significantly more over rest of the sowing dates. The minimum number of days (36 days) to reach 1 st flower appearance stage was noticed in 19 Oct (D 2 ) sowing which was comparable with all its succeeding dates sown crops. The cv. ASB 22 (V 2 ) took 43 days to reach 1 st flower appearance stage in 3 Oct (D 1 ) date sown crop which was significantly more over all its succeeding dates sowings. The 19 Oct (D 2 ) sowing was taken least number of days (35 days) to attain 1 st flower appearance stage which was at par with D 4, D 6 and D 7 and remained significantly lower than rest of the dates sown crops. The cv. KDS 726 (V 3 ) took a maximum number of days (47 days) to reach 1 st flower appearance stage in 3 Nov (D 3 ) date sown crop which was on par with D 2, D 8 and D 9 and significantly more than the rest of the date sown crops. The minimum number of days (41 days) to attain 1 st flower appearance stage was noticed in 19 Nov (D 4 ) sown crop which was comparable with D 1, D 2, D 5, D 6 and D 7 and significantly less than all other dates of sowings. These results are in line with the findings of Gochar et al. (2022) [2] .

Days to 1 st pod appearance stage

The days to attain 1 st pod appearance stage was influenced by interaction effect of varieties and sowing dates (Table 1). The cv. KDS 726 (V 3 ) sown on 3 Feb (D 2 ) took significantly more number of days (56 days) to reach 1 st pod appearance stage which was 12 and 8 days more over cv. JS 335 (12 days) and cv. ASB 22 (8 days), respectively. A similar trend was also observed in D 2, D 3, D 4, D 6, D 7 and D 8 date sowings. But in 3 Oct and 3 Dec sown crops, there was no significant variation among the cultivars was noticed in days to 1 st pod appearance stage. The above results indicate that, the difference in duration among the cultivars required from 1 st flower appearance to 1 st pod appearance largely governed by prevailing weather conditions and cultivar sensitivity. Individual varietal performance under different dates of sowing showed that, the cv. JS 335 (V 1 ) has taken more number of days (46 days) to attain 1 st pod appearance stage in 3 Oct (D 1 ) sowing which was comparable with D 3 , D 4, D 5, D 6, D 8 and D 9 sowings and significantly more over rest of the dates sown crops. The minimum number of days (40 days) to reach 1 st pod appearance stage was observed in 19 Oct (D 2 ) sowing which was comparable with D 3, D 4, D 5, D 6, D 7 and D 9 sowings remained significantly inferior to the rest of dates sown crops. The cv. ASB 22 (V 2 ) attained 1 st pod appearance stage in 48 days with 3 Feb (D 9 ) date sown crop which was on par with D 1, D 3, D 5, D 7 and D 8 sowing dates and significantly more over rest of the dates sown crop. The minimum number of days (39 days) to attain 1 st pod appearance stage was noticed in 19 Oct (D 2 ) sowing which was at par with D 4 and D 6 dates sowings and remained significantly inferior to rest of the date sown crops. The cv. KDS 726 (V 3 ) took the maximum number of days (56 days) to reach 1 st pod appearance stage in 3 Feb (D 9 ) date sown crop which was on par with D 3, D 7 and D 8 sowings and significantly more over remaining dates of sowings. The minimum number of days (46 days) to attain 1 st pod appearance stage was noticed in 3 Oct (D 1 ) sown crop which was comparable with D 4, D 5 and D 6 significantly lower to all other dates of sowings.

Days to 1 st pod dry stage

The days to attain 1 st pod dry stage influenced by interaction effect of varieties and sowing dates (Table 1). The cv. KDS 726 (V 3 ) sown on 19 Dec (D 6 ) taken more number of days (92 days) to attain 1 st pod dry stage which was significantly more over cv. JS 335 (V 1 ) and cv. ASB 22 (V 2 ). This trend was also reflected in D 2, D 3, D 4, D 5, D 7, D 8 and D 9 date sown crops. The days to attain 1 st pod dry stage was on par with each other among the cultivars in 3 Oct (D 1 ) sowing date. Individual varietal performance under different dates of sowing showed that, The cv. JS 335 (V 1 ) required 80 days to attain 1 st pod dry stage in 19 Jan (D 8 ) sown crop which was comparable with 3 Nov (D 3 ) sown crop and significantly more over rest of the dates of sowings. The minimum number of 68 days to reach 1 st pod dry stage was noticed in 19 Oct (D 2 ) sowing. Similar trend was also exhibited by the cv. ASB 22 (V 2 ). The cv. KDS 726 (V 3 ) took the maximum number of days (92 days) to reach 1 st pod dry stage in 19 Dec (D 6 ) date sown crop which was comparable with D 3 , D 7 and D 8 and significantly more over remaining dates sown crop. The lower number of days (73 days) to attain 1 st pod dry stage was noticed in 3 Oct (D 1 ) sown crop.

Days to 75% pods dry stage

A significant difference was observed in days to attain 75% pods dry stage with their interaction effect (Table 1). The perusal of data from the Table 1 revealed that, the cultivars did not differ significantly to attain 75% pods dry stage in D 1 and D 9 dates sowings. The cv. KDS 726 (V 3 ) sown on 19 Dec (D 6 ) was taken 99 days to attain 75% pods dry stage which was significantly more over cv. JS 335 (79 days) and cv. ASB 22 (82 days). This similar trend was also noticed in D 2, D 3, D 4, D 5, D 7 and D 8 date sown crops. Individual varietal performance under different dates of sowing showed that, the cv. JS 335 (V 1 ) took 86 days to attain 75% pods dry stage in 19 Jan (D 8 ) sown crop which was on par with D 3, D 6 and D 9 sowings and significantly more over remaining dates sown crop. The minimum number of days (75 days) to attain 75% pods dry stage was noticed in 3 Oct (D 1 ) sowing which was comparable with D 2 to D 7 and D 9 sowings and remained significantly lower to the rest of the dates sown crop. The cv. ASB 22 (V 2 ) required 85 days to reach 75% pods dry stage in 19 Jan (D 8 ) sown crop which was comparable with D 3, D 4, D 6, D 7 and D 9 sowings and significantly more over remaining dates sown crop. The minimum number of days (77 days) to attain 75% pods dry stage was noticed in 3 Oct (D 1 ) sowing which was on par with D 2 to D 7 and D 9 dates sowings and remained significantly inferior to rest of the dates sown crops. The cv. KDS 726 (V 3 ) reached 75% pods dry stage within 99 days in 19 Dec (D 6 ) date sown crop which was on par with D 3, D 7 and D 8 sowing dates and significantly more than the rest of the dates sowings. The least number of days (78 days) to attain 75% pods dry stage was observed in 3 Oct (D 1 ) sown crop which was comparable to D 9 sowing date and significantly lower to all other dates of sowings. Similar findings were also reported by Gochar et al. (2022) [2] and Kandil et al. (2019) [4] .

Conclusion

From the above results it can be concluded that sowing date had a minor impact on emergence, it significantly affected later stages like bud appearance, flower, and pod formation and the cv. KDS 726 taken more number of days to bud appearance, 1 st flower appearance, 1 st pod appearance, 1 st pod dry and 75% pods dry stages followed by the cv. ASB 22 and least was with the cv. JS 335.

Acknowledgement

I extend my sincere thanks to Dr. B. Balaji Naik, Principal scientist & Head, Agronomy (major guide) and to my advisory committee members for giving me proper guidance throughout the course of study.

References

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