The effect of different levels of salinity stress on early-maturing genotypes grass pea (Lathyrus sativus L.) genotypes at various harvest times

Grass pea is one of the most important crops and forage plants in the world, which is known for its high protein and lysine content. Due to the importance of this plant among forage plants in terms of livestock nutrition, planting in low-yielding lands, resistance to stresses, and also their role in soil fertility, they are extensively used. To investigate the response of early-maturing grass pea genotypes to salinity stress, 26 genotypes were studied in a factorial experiment based on RCBD with two replications. Salinity treatments were applied at four levels NaCl and various traits were evaluated. The number of plants in each pot after thinning was five plants, and at the end of the growing season, one plant was harvested from each pot every week. In the first harvest, genotype had a significant effect on pod dry weight and leaf length, and salinity had a significant effect on shoot dry weight, leaf number and root length. In this harvest, for the root length, the lowest average was in the first level of salinity and the other three levels were in the same group, that is, in the conditions of salinity stress, the root grew more than the control. In the second harvest, the genotype had a significant effect on the traits of number of pods, plant height, number of leaves, number of grains per pods, leaf angle, leaf length, number of branches and root length. The effect of salinity was significant for root length. In the root length, the least effect of salinity was related to the first level and the second and third levels were placed in the same group, which increased the root length with the increase of salinity. In the third harvest, the genotype had a significant effect on pod fresh weight, leaf length, pod dry weight and number of branches. The effect of salinity on the dry weight of the pod was significant, and other traits had not a significant difference for any of the effects. Also, in this harvest, the fourth level of salinity was removed. The results of the fourth harvest showed that the genotype had a significant effect on the traits of pod dry weight, number of grains, number of grains per pods, plant height, pod fresh weight, number of branches and location of the first branch. Dry weight of shoot, fresh weight of pod, dry weight of pod, number of grains, number of grains per pod, plant height and number of leaves were significant for the effect of salinity. With the increase in salinity, the dry weight of the pod increased and the number of grains and the number of leaves decreased. In this harvest, the traits dry weight of shoot, fresh weight of pod, dry weight of pod, number of grains, number of grains in pod, plant height and number of leaves, which are components of yield, were affected by salinity. The results of the fifth harvest showed that the genotype had a significant effect on the number of branches. The effect of salinity was significant for dry weight of shoot, fresh weight of shoot, fresh weight of pod, dry weight of pod, number of grains and number of grains in pod, leaf length and plant height. The effect of salinity on yield was consistent with the results of the fourth week. The genotypes showed different reactions in different weeks, which may be because genotypes are exposed more time to salinity, they show the more different reactions. Also, in the first and second harvests, salinity had a significant effect on root length, and with increasing salinity, root length increased. The dry weight of shoots was affected by salinity stress in the first and fourth harvests, and salinity had no significant effect on it in the second and third harvests. In general, it can be said that in the first and second harvests, salinity had a significant effect on root length, and with increasing salinity, root length increased. The dry weight of shoots was affected by salinity stress in the first, fourth and fifth harvests, and salinity had no significant effect on it in the second and third harvests.