Solid matrix priming improves seed emergence and crop performance in okra

Low and erratic emergence of okra is a major problem under low temperatures and poor stand establishment leads to low productivity. Okra growers currently prefer to use high seed rate during early spring plantings to achieve good plant stands. Solid matrix priming (SMP) alone or in combination with Trichoderma viride or Captan, hydropriming and non-primed seeds were evaluated for seedling emergence and crop performance under optimal and sub-optimal temperatures. SMP improved laboratory germination at suboptimal temperatures (15 degrees C) and reduced mean days to germination from 12.0 days (non-primed) to 8.5 days. SMP also improved germination at optimal temperatures (25 degrees C) but had no effect on mean days to germination. Applications of Trichoderma viride or Captan provided no additional benefit in improving laboratory seed germination of solid matrix primed seeds. Hydro-priming also improved laboratory germination similar to that of SMP. In both suboptimal and optimal temperatures in the field, the emergence of hydroprimed seeds was similar to the untreated control. However, SMP in combination with Trichoderma viride improved field emergence by 19% in conditions of sub-optimal temperatures and by 11% in optimal temperatures compared with the non-primed control. Final marketable pod yield under sub-optimal temperature was also improved by SMP alone or in combination with Trichoderma vi ride. but not under optimal temperatures. Priming had no effect on the number of pods per plant and pod yield per plant under either environment. The seed leachate from primed seed had low electrical conductivity, total free amino acids and water soluble sugars, suggesting better integrity of membranes. Imbibed primed seeds also showed greater activities of two enzymes of the glyoxylate cycle, isocitrate lyase and malate dehydrogenase, which are involved in lipid to sugar conversion during germination. The results suggest that solid matrix priming in combination with Trichoderma viride can be successfully used to improve seedling emergence and productivity of okra under low temperatures.