Applications of signal transduction and xerophytophysiology by exposing hypocotyls in organic peanut production

Summary

The AnM practices in peanut production included three steps. The three letters, A, n and M, showed the shapes of the section-cross of the ridge at the three steps of different growth stages of the peanut crop. First, the peanut seeds were sown a little deeper than usual, about 8 cm, in the ridge to induce the extra-elongation of the hypocotyl. When the seeds were sown, the cross-section of the ridge looked like the letter “A”. The second, the hypocotyls elongated more than usual were exposed to light and dry air by removing the soil away around the young seedlings just after the emergence. At this time, the cross-section of the ridge looked like the letter “n”. The third, at the middle growth stages, soils on the both sides of ridge were earthed up to welcome the late pegs. At this time, the cross-section of the ridge looked like the letter “M”. Physiologically, the AnM technique induced osmotic adjustment, which improved photosynthetic activities by maintaining a higher leaf turgor potential. Anthocyanin accumulation was observed visually in hypocotyls of the young seedlings soon after the hypocotyl exposure started. The anthocyanin accumulation is accompanied by accumulations of soluble sugars, soluble proteins. All the consequences of the xerophytophysiological responses collaborated together to make the crop healthier through their individual function in plant growth and development. Gdi-15 (Groundnut desiccation induced) gene is a stress-responsive gene in peanut plant and its up-regulation expression was found in hypocotyl. In overall, hypocotyl exposure as a stimulation did induce the up-expression of the drought responsive gene, Gdi-15, and the consequent osmotic adjustment and anthocyanin accumulation but caused no damage to the whole plant. The AnM practice was more effective in the soil with compost applied to the surface layer and therefore it is feasible in organic peanut production.