Effect of Soil Compaction and Seed Priming on Growth Indices and Proline Content of Kidney Bean Seedling

Heavy soil compaction and crusting has adverse effects on the rate and speed of seedling emergence, as well as percent of established seedling, particularly in dicotyledonous epigeal plants. Therefore, the aim of this study was to evaluate the ways of coping with this phenomenon in kidney bean. The experiment was carried out during the years 2017 and 2018 in the Seed Laboratory and Greenhouse of Lorestan University, Iran. Factors studied were seed priming (control, hydroprming, GA50 ppm, GA100 ppm, SA50 ppm, SA100 ppm, and GA50 ppm+SA50 ppm) and soil compaction (intact, 5%, 10%, 15%, and 20% more compaction in relation to intact). The results showed that low soil compaction (5-10%) had positive effect on seedling growth, while, more compaction had adverse effect. Seed priming had a significant effect on seedling growth indices. Priming improved root length and number of root branches. Sever soil compaction decreased root length. The maximum root length (40.58 cm) was observed in priming with GA50 ppm+SA50 ppm and no soil compaction (intact soil). The greatest number of root branches was observed in GA50 ppm+SA50 ppm and 20% soil compaction. Seed priming had significant effects on proline. Minimum proline content (85.1 µg.g-1 FW) was observed in not-primed and 10% soil compaction, however, its maximum  (199.6 µg.g-1 FW) was recorded in GA50 ppm+SA50 ppm priming and no soil compaction (intact soil). In general, weak soil compaction (5%) improved seedling growth, but increasing soil compaction by 15% or more decreased root (9.13 cm) and shoot growth. It seems that soil compaction reduces water and mineral uptake, hence reducing seedling performance.