Effect of sowing date on phenologic stages and yield of Quinoa (Chenopodium quinoa Willd.) under saline condition

Introduction Phenological growth and development is very important for determination of sowing date and agronomic practices in different climate condition. Quinoa has been cultivated in the Bolivian and Peruvian Andean region for 7000 years. Worldwide interest on this crop is increasing because of high nutritional quality. Quinoa is gluten free peuduo cereal and suitable for celiac patients, and whole grain consumption prevent type 2 diabetes and because of low glycemic index can be replace common cereal in diabetes diet. Of more than 50 000 edible plant species in the world, only a few hundred contribute significantly to food supplies. Just 15 crop plants provide 90 percent of the world's food energy intake, with three rice, maize and wheat - making up two-thirds of this. Quinoa is a facultative halophyte plant species and some varieties are able to complete life cycle at 400 mM salinity. Quinoa growth was stimulated by moderate salinity (10 dS m-1). Quinoa is interest in Iran for high tolerance to abiotic stress and as a new crop for saline area. The aim of this study was selection of the best sowing date for early mature cultivar of quinoa. Material and methods For evaluation of different climate condition on phenological growth stage and seed yield, quinoa (NSRCQ1) was planted in eight sowing date (22 Aug, 6 Sep, 26 Sep, 7 Oct, 24 Oct, 24 Feb, 7 March and 30 March) with 14 dS m-1 saline water in Yazd, Iran. One of the main pests of the quinoa which was feed leaves during vegetative growth stage in all sowing date was Spodoptera exigua. This pest controlled by Avant and Saypermetrin. Growing degree day of different growth stage was calculated by dent-like function. Data was analyzed with randomized complete block model using SAS. Treatment means were compared using least significant difference (LSD) test at P=0.05. Results Results showed that quinoa produced 2.34 t ha-1 at the first sowing date and complete life cycle during 108 days. Frost damage occurred at -4.5 °C in 26 Sep sowing date at flowering stage. In Oct sowing date crop can survive during winter but could not produce the seed. Feb sowing date produced 1.6 t ha-1 and crop cycle complete during 132 days. High temperature (above 32 °C) in Feb and March sowing date and low temperature (13.6 °C) in Sep sowing date during grain filling period reduced seed yield and size. Flowering and seed filling stages were sensitive to photoperiod (based on phenological stage response to growing degree day). Quinoa (NSRC Q1) had a short day quantitative response to photoperiod and photoperiod longer than 12 hours prolonged time to flowering. Among the sowing dates 22th Aug was selected because of shorter growing cycle and higher seed production in Yazd provinces. Conclusion Among the growth stage grain filling period is sensitive to high and low temperature and the best temperature was 20 ºC. Flowering time and grain filling stage is sensitive to photoperiod and day length longer than 12 hours increased GDD requirement. In 22th Aug sowing date 560 mm saline water (14 dS m-1) was applied in Yazd. In spring sowing date growing cycle prolong to 132 days and seed yield and weight were lower than Aug sowing date. Plant produced higher biomass but during seed filling period high temperature reduced seed yield. For Central Plateau of Iran the best sowing date is in the late of Aug. Based on the weather and phenological data and weather data the best sowing date of this genotype for different agroecological zone could be predicted.