Germination enhancement of Oryza sativa var. Nerica under 2D-clinostat induced microgravity environment

Modification of physiological processes may be used to offset the negative effects of gravity on plant growth and development. This study was set up to assess the efficacy of sodium nitroprusside (SNP) and indole-3-acetic acid (IAA) in improving the germination characteristics of Oryza sativa var. Nerica in microgravity. The seeds were primed with SNP and IAA solutions, which were then divided into three concentrations: 100, 500, and 1000 mg/L. The primed rice seeds were then inoculated and mounted on the Clinostat at 2 rpm for 168 h. Under microgravity, the germination of rice was found to be impaired. However, germination was increased when IAA and SNP were used under the simulated microgravity conditions. For instance, seedlings exposed to 100 ppm IAA had at least 10% germination within the first 48 h and 100% germination within the first 120 h. Also, seedlings treated with 100 ppm SNP under microgravity showed a significantly improved germination response with 40% germination occurring within 48 h and 100% germination occurring within the first 72 h. Although microgravity caused an initial 83-h delay in germination, this was reduced to less than 45 h when seeds were pretreated with 100 ppm IAA and SNP. Regardless of the chemical agent used as the growth-stimulating component, there was more variation with germination time than with apparent changes in results induced by treatment concentrations. The study also reinforces the importance of chlorophyll to plant productivity because of the effects of the treatments on chlorophyll concentration, especially IAA. Moreover, the use of IAA and SNP is a promising strategy for mitigating the negative physiological effects of microgravity.