Effect of Different Water Temperatures on the Germination of Flemingia semialata Seedlings

Introduction

Lac insects, a critical component of the lac ecosystem, thrive on more than 400 plant species, including F. semialata (Sharma et al., 2006) [1] . Flemingia semialata, a nitrogen-fixing leguminous species, plays an important role in agroforestry systems by improving soil fertility and supporting biodiversity. While environmental factors such as soil type and light are well-documented, the impact of water temperature on the germination and early growth of F. semialata remains less understood. Germination is a critical phase for successful establishment, and water temperature affects enzymatic processes and metabolic rates in seeds. This study aims to investigate how varying water temperatures influence the seedling germination of Flemingia semialata.

Materials and Methods

Seed Collection and Preparation

F. semialata seeds were collected from the ICAR-National Institute of Secondary Agriculture, Ranchi, Jharkhand. Prior to the experiment, the seeds were soaked in running tap water for 5 minutes to remove unhealthy seeds and debris, ensuring that only healthy seeds were used in the experiment.

Water Temperature Treatments

The seeds of F. semialata were subjected to five water temperature treatments, each with three replicates. The temperature treatments were set at five distinct levels: 20 °C, 40 °C, 60 °C, 80 °C, and 100 °C. Additionally, each temperature was tested for three different durations: 5 minutes, 10 minutes, and 15 minutes. The experimental design aimed to evaluate the effect of varying temperatures and treatment durations on seed performance. Water was heated and poured into glass beakers, and the temperatures were checked using a thermometer. The washed F. semialata seeds were added to the water in the beakers, with each beaker corresponding to a specific temperature treatment. Three beakers were used for each temperature condition. To maintain the desired water temperature, the beakers containing the seeds were placed in temperature-controlled incubators. The temperature was regularly monitored using digital thermometers to ensure consistent conditions throughout the experiment.

Seed Sowing and Data Collection

The treated seeds were transferred to plastic trays filled with vermiculite to provide a consistent nutrient medium for seedling germination. After one week, the number of growing seedlings was counted at two-day intervals for up to 4 weeks. The recorded seedling counts were used to analyse the performance of the seedlings under different temperature treatments and time durations.

Results

The seed treatment of F. semialata at varying temperatures and durations significantly influenced seedling performance. The number of seedlings was recorded over a period of four weeks, revealing notable trends in germination success. Seed treatments at 80 °C for 15 minutes demonstrated the highest seedling performance, followed by 60 °C, 100 °C, and 40 °C treatments. In contrast, the lowest seedling germination was consistently observed in treatments at 20 °C, regardless of the duration. These findings suggest that higher temperatures, within a certain range, enhance the germination and early growth of F. semialata, while lower temperatures inhibit seedling establishment.

Discussion

Temperature plays a critical role in determining the duration of seed germination (Seefeldt et al., 2002) [2] . The results of this study indicate that F. semialata seeds exhibit optimal germination at 80 °C. The temperature sensitivity observed in the germination process is consistent with other leguminous species, which often show peak germination at moderate temperatures. The decline in germination at 100 °C could be attributed to temperature-induced stress, which interferes with metabolic processes required for seedling development. Higher temperatures accelerate metabolic activity, potentially leading to faster depletion of seed reserves (Roberts, 1988) [4] , while lower temperatures may slow enzymatic activity and reduce water uptake, delaying germination (Bewley & Black, 1994) [3] . These findings suggest that F. semialata is best suited for regions with moderate, stable temperatures that support faster germination and vigorous seedling growth.

Conclusion

This sudy demonstrates that temperature and treatment duration significantly affect the germination and early growth of Flemingia semialata seeds. The optimal temperature for seedling performance was observed at 80 °C for 15 minutes, while lower temperatures, particularly 20 °C, resulted in the poorest germination rates. The results suggest that F. semialata seedlings benefit from higher treatment temperatures, but excessive heat, such as 100 °C, can induce stress and hinder germination. Additionally, cooler temperatures (e.g., 20 °C) may impede enzymatic activity and water uptake, leading to delayed or poor germination This study provides valuable insights for optimizing seed treatment protocols for F. semialata and similar species to enhance their propagation and early development.

Acknowledgement

We are grateful to the "Network Project on Conservation of Lac Insect Genetic Resources" (NP-CLIGR), ICAR-NISA,

References

1. Sharma K, Jaiswal AK, Kumar KK. Role of lac culture in biodiversity conservation: Issues at stake and conservation strategy. Curr Sci. 2006;89(6):894-898.
2. Seefeldt SS, Kidwell KK, Waller JE. Base growth temperatures, germination rates, and growth response of contemporary spring wheat (Triticum aestivum L.) cultivars from the US Pacific Northwest. Field Crops Res. 2002;75(1):47-52.
3. Roberts EH. Temperature and seed germination. Symp Soc Exp Biol. 1988;42:31-47.
4. Srivastava SK, Jeet P. Effect of Irrigation Methods and Mulching on Growth and Seed Yield of Semialata: Performance evaluation of different irrigation and mulch for Flemingia semialata. Journal of AgriSearch. 2020 Mar 9;7(1):18-20.