Macronutrients and biochemical compounds' changes in the leaves and corms of the saffron plant (Crocus sativus L.) during the final stages of growth

This study was carried out to examine how macronutrients and biochemical compounds in the leaves and corms of the saffron plant (Crocus sativus L.) changed during its final stages of development. The samples of leaves and corms were collected at 170,185, 200, and 215 days after the first irrigation (DAFI). The data was analyzed using a randomized complete block design with four sampling times (170, 185, 200, and 215 DAFI) with three replications. The results indicated that the concentration of total chlorophyll, chlorophyll a, and chlorophyll b decreased when the interval between the first irrigation and sampling increased. However, the decrease was more intense from 170 to 185 DAFI. During the final stages of growth, chlorophyll concentration decreased with the decline of magnesium, phosphorus, and nitrogen in the leaves. However, the intense decrease of these macronutrients happened in 170 to 185 DAFI. The concentration of carotenoids decreased during the 200 to 215 DAFI interval. Superoxide dismutase (SOD) levels in the leaves began to increase until 200 DAFI, then quickly declined. In both the corms and the leaves, the concentration of the polyphenol oxidases (PPOs) enzyme decreased intensively at 185 DAFI, and then until the last sampling, its activity increased in both. According to this study, saffron plants enter the senescence stage at approximately 170 DAFI. Therefore, it is recommended that foliar application be applied before this interval to delay senescence and increase the size of the corms.