Identification of climatic and physiological variables associated with rice (Oryza sativa L.) yield under tropical conditions

Rice crop productivity is influenced by climatic conditions such as solar radiation, temperature, and water availability during its vegetative and reproductive stage. In Colombia, rice cultivation is carried out throughout the year; so, it is necessary to identify the sowing dates where high yields are obtained, and which physiologic and climatic factors significantly influence them. Therefore, this research aimed to identify the key climatic and physiological factors that allow maximizing the yield and maintaining good productivity in sowing dates with optimal and deficient environmental conditions, respectively. The experiment was carried out in a rice producing region in northern of Tolima, Colombia from 2015 to 2016. Ten sowing dates were established, with a randomized complete block design in a divided strips arrangement. For each sowing date, climatic conditions were tracked, and growth, development, and yield of rice plant were evaluated. Also, the photosynthetic rate was assessed on five sowing dates. Results showed that physiologic factors that have more relation with crop yield are plant height, leaf area index and dry mass accumulation between phenological stages 37 and 49; whereas the unique climatic factor, that was highly related to yield, was solar radiation between phenological stages 51 to 77. Furthermore, when the optimum values of each variable were reached, a yield higher than 9,500 kg ha-1 was achieved. No relation was observed between the photosynthesis rate of at leaf level and yield.