Research Article

Morpho-physiological and phenological response of rice (Oryza sativa L.) genotypes to low temperature stress at reproductive stage

 Yasmeen Begum¹, R. P. Patil², M. K. Meena¹, K. Mahantashivayogayya³, T. C. Suma¹ and M. Lakshmikanth⁴

¹Department of Crop Physiology, College of Agriculture, Raichur, University of Agricultural Sciences, Raichur, Karnataka, India

²Department of Crop Physiology College of Agriculture, Bheemarayana gudi, University of Agricultural Sciences, Raichur, Karnataka, India

³Scientist, Rice Breeder, ARS, Gangavathi, University of Agricultural Sciences, Raichur, Karnataka, India

⁴Department of Soil Science and Agril. Chemistry College of Agriculture, University of Agricultural Sciences, Raichur, Karnataka, India

Corresponding author e-mail: yasmeen16400@gmail.com

(Received: 28/01/2022; Revised: 20/05/2023; Accepted: 23/05/2023)

ABSTRACT

The yearly changes in atmospheric temperature are projected to negatively affect food production in several locations. Rice exposure to low-temperature stress can decrease plant growth in different stages, notably during the reproductive period. A field experiment was conducted in ARS Gangavathi, Karnataka. The experiment laid out in factorial randomized block design where four different rice genotypes (GNV-10-89, GNV-1801, GNV-1108 and BPT-5204) transplanted under two different dates of transplanting D₁ (normal Kharif-15^th September) and D₂ (late Kharif-30^th September). The low temperature during the reproductive stage was 14.1°C which inhibited the morphological, physiological, phenological and yield traits of rice crop. All the observations were recorded at the flowering stage (95 DAT). The results revealed that morphological traits like plant height, number of green leaves, number of productive tillers, total dry matter, total leaf area and root length were high in D₁ than D₂ (101.6 & 99.76 cm, 21.5 & 16.1 hill^-1, 14.5 & 11.5 hill^-1, 29.0 &21.1 g hill^-1, 3.79 & 4.11 dm² hill^-1 and 14.6 & 18.2 cm), physiological traits such as photosynthetic rate (14.55 & 13.45 µ mole CO₂ m^-2 s^-1) and Transpiration rate (12.86 & 11.01 m mole H₂O m^-2 s^-1) similarly phenological traits, DPI (80.6 & 90.5 days), DF (98.3 & 102.3 days), DPM (116.7 & 127.2 days) and DHM (124.7 & 135.4 days). Reproductive traits like pollen viability (91.3 & 87.4 %) and spikelet fertility (84.3 & 75.9 %) and grain yield (7744.8 & 6531.3 kg ha^-1). Among the genotypes GNV-10-89 (10270.9 kg ha^-1) recorded the higher grain yield and lower was observed in BPT-5204 (3937.5 kg ha^-1) these results conclude that the late Kharif transplanting was not suitable for this region as there was sharp drop-down of temperature (14.1°C) at a reproductive stage which leads to high spikelet sterility. By looking at the results obtained, among four genotypes GNV-10-89 recorded high grain yield followed by GNV-1108 these two genotypes are considered as moderately tolerant, GNV-1801 is moderately sensitive and BPT-5204 is sensitive to low-temperature stress.

Keywords: Low temperature stress, Rice crop, Reproductive stage, Phenological traits and Grain yield