عنوان مقاله [English]
The world population is increasing daily while the scope for expansion and development of agricultural land is very narrow due to limited water resources. All of this can affect agriculture indirectly or directly. Quinoa is a pseudo-cereal, belongs to the Amaranthaceae family and is native to South America. This crop is important for human and animal nutrition due to its medicinal and agro-industrial properties. Water and nitrogen (N) are two major challenges in quinoa cultivation that can be addressed by better understanding related agronomic features. Drought stress is the most important factor in yield loss among environmental inhibitors on crops that disrupts many morphological and physiological features associated with plant growth and development. Under water deficit conditions, selection and cultivation of crop species tolerant to drought stress is an approach to maintain and/or increase crop production levels. Although it is widely reported that quinoa is a highly drought-tolerant crop, but its growth has been significantly suppressed under severe drought stress conditions.
Materials and Methods
The experiment was conducted as a split factorial arranged in a randomized complete blocks design with three replications. Treatments included four irrigation regimes (100, 80, 60, and 40% of crop water requirement) as the main factor, three quinoa cultivars (TITICACA, Q29, and GIZA1), and three N rates, (0, 100 and 200 kg/ha from urea source) as sub factorial. The field preparation operations prior to planting, included plowing and disc. The distance between two rows and between plants on the row in quinoa cultivation was 50 cm and 10 cm, respectively.
Results and Discussion
There was a significant interaction effect between irrigation, N, and cultivar on root traits, grain yield. The effects of irrigation regimes, N rates and their interactions were significant on plant height at the level of one percent and the highest (109 cm) and lowest (50 cm) plant height was obtained with normal irrigation and 100% N application in GIZA1 cultivar and 40% of water requirement 100 kg.h-1 N application in cultivar Q29, respectively. The highest 1000-seed weight was obtained with normal irrigation (2.93 g) regime to 80% of water requirement (2.91 g) in GIZA1 cultivar. The lowest 1000-seed weight was obtained with 40% of plant water requirement in all three cultivars. Thousand-grain weight in Q29 and TITICACA cultivars is the same in all irrigation regimes. Two treatments of the normal irrigation, N application and GIZA1 cultivar; and 40% of water requirement,200 to 100 kg.h-1 of N rate and Q29 cultivar obtained the highest (3326 kg ha-1) and lowest (686 kg ha-1) seed yield, respectively. The N addition reduced seed yield in quinoa cultivars under water shortage conditions.
With the higher N application, the GIAZ1 cultivar performed better than the others. Although TITICACA cultivar recorded lower grain yield under optimum irrigation conditions, it showed higher grain yield under severe stress conditions, compared with others. It can be concluded that in the conditions of 100% water requirement and the application of 200 kg of nitrogen per hectare, GIAZ1 variety is suitable for the growth of quinoa in the ecological conditions of Ilam region.