Super absorbent polymer application in seeds and planting furrow: it will be a new opportunity for rainfed agriculture

Abstract

Brazil is the fourth largest grain producer in the world. Its agriculture is mainly rainfed, with two cropping seasons per year. While the first crop (i.e., spring/summer) receives greater precipitation, the second crop (i.e., autumn/winter) is associated with greater risk of crop failure mainly due to the low rainfall, suggesting that technologies that could optimize water use during that period are needed. Superabsorbent polymers (SAP) are used in the forestry sector to reduce seedling mortality and the frequency of irrigation of eucalyptus and pinus glue owing to their ability to increase water storage capacity in the soil. However, to our knowledge, very little is known about the use of PSA in annual agricultural crops. To this end, the effects of PSA, as a seed coat or applied in the planting grooves, on the initial development of sorghum seedlings under conditions of water deficit were evaluated in two experiments under greenhouse conditions. In experiment 1, sorghum seeds with and without PSA coating were seeded in trays and subjected to three irrigation intervals to induce water deficit. The percentage of emergence and emergence speed index were evaluated and, at 26 days after sowing, seedling height, number of leaves per plant, survival rate, and dry mass of shoot and root were evaluated. In experiment 2, the seeds of sorghum with and without PSA coating were sown in pots, with PSA applied in the planting grooves. At 30 days after sowing, the plant stand, number of leaves per plant, plant height, and dry matter mass of leaves, stem, and root were evaluated. The results showed that PSA applied both as a seed coat and in planting grooves increased seedling growth and dry mass of aerial parts at 26 days and 30 days for experiments 1 and 2, respectively. In addition, seed coating with PSA increased plant survival rate, but reduced the rate of seedling emergence in both experiments. Therefore, the use of PSA as a seed coat or applied in the planting groove has beneficial effects on the vegetative development of sorghum under low water conditions. Further research is needed to address the effect of PSA on seedling emergence.