Reaction of Germination and Seedling Growth of Redroot Pigweed (Amaranthus retroflexus) to Salinity and Drought Stress

Abstract

Salt and drought are two major environmental stresses that affect growth and development of plants. In order to study the effects of sodium chloride and polyethylene glycol (6000) on germination characteristics and early seedling growth of redroot pigweed (Amaranthus retroflexus), two completely randomized designs with 4 replications were conducted at Weed Research Laboratory of Bu-Ali Sina University, Hamedan in 2015. The treatments were salt and drought stress as osmotic potential at six levels (zero (control),-2,-4,-6,-8 and-10 bar). The results showed that when stress increased, germination percentage, germination speed, radicle and plumule length, seedling length and seedling vigor index decreased significantly (p≤ 0.05). With an increase in the intensity of salt and drought stress from zero to-10 bars, redroot pigweed seed germination reduced about 96 and 100 percent, respectively, compared with the control. The highest seedling length in both stresses was observed in the control (7.71 cm) and by increasing stress intensity to-10 bars in both salinity and drought stresses, seedling length was reduced to 1.52 cm and 0 cm, respectively. Fitting of the three-parameter logistic model provided a successful estimation of the relationship between salt and drought stress levels and germination percentage of redroot pigweed as well as germination speed. This model showed that salinity and drought stress at-3.58 and-3.75 bars caused a 50% reduction in maximum germination percentage of redroot pigweed. In addition, 50% decrease in germination speed caused by salinity and drought stress was observed in-2.58 and-2.88 bars, respectively.

Advanced Strategic Research to Promote the Use of Rice Genetic Resources

“…In most cases in developing countries, farmer's seed lots are stored at ambient conditions, which leave seed viability and vigor vulnerable to the increased frequency of hot and humid weather under climate change [16]. Lower seed vigor can result in poor crop establishment in direct-seeding cultivation, and even more severely under unfavorable crop environments such as drought [17,18]. While determining seed longevity of genebank accessions, donor germplasm having high seed longevity could be selected and used for the breeding work enhancing seed longevity of popular crop varieties [19].…”