Effect of Sowing Date on Dry Matter Accumulation, Yield and Yield Components of Different Genotypes of Quinoa (Chenopodium quinoa Willd.)

Quinoa (Chenopodium quinoa Willd) is a dicotyledonous plant that belongs to family Amaranthaceae and subfamily Chenopodiaceae, native to the Andes of the Americas. Due to the climatic diversity of Iran, one of the notable cases is the study of planting history as the most important factor in adapting and increasing plant yield; therefore, this study was conducted to determine the optimum sowing date of quinoa in Kavar (city of Fars province). In that experiment, the yield response and the yield components of different cultivars of quinoa were examined in relation to the different sowing dates in spring cultivation.

In order to study and determine the most suitable genotype and sowing date of Quinoa, a factorial experiment was conducted with three replications in Kavar, Fars, Iran. Experimental treatments included five quinoa genotypes (Q29, Q26, Red Carina, Titicaca, and Giza1) on the three dates of February 10 and 20, and March 1, in the two years of 2018 and 2019.Each experimental plot consisted of five rows, five m in length and 30 cm apart. Seeds were sown at a density of 67 seeds.m-2. Plants in the three center rows (three m long) in each plot were used for the measurements of the yield of the grain and its components. To determine the number of panicles per unit area, before the final harvest, count half a meter in each experimental plot, specific quadrants was used to count the number of panicles. To calculate the weight: each thousand seeds (1000 seeds) of the seeded seeds were randomly counted with each seed counting machine and weighed with an electric scale (with an accuracy of one thousandth of a gram), And from the division of grain yield to biological yield, the harvest index was calculated. To measure the height of the plant from each experimental plot, 10 plants were randomly selected and the necessary measurements were performed. Water use efficiency (WUE) in the plant was calculated from the division of grain yield to amount of water used. The growth and Efficiency and contribution of materials remobilization were measured too.

The present results showed that sowing date and genotype had a significant effect on grain yield, plant height, and 1000 grain weight, biomass and number of panicles. The most plant height belonged to the Titicaca genotype on the second and third sowing dates. Q26 had the highest 1000 grain weight among the studied genotypes and was obtained on February 10 sowing date. The relationship between WUE and yield was linear regression in different genotypes positively and significantly (r2= 0.715) and the highest WUE belonged to Giza1 genotype on February 10 (1.4 kg.m-3). The effect of sowing date and genotype on dry matter accumulation rate, remobilization contribution and remobilization efficiency of photosynthetic materials were significant. Q29 genotype had the highest rate of dry matter accumulation (6.1 g.m-2.day-1). The highest remobilization contribution of stored materials and their efficiency belonged to the sowing of quinoa on February 10. The highest grain yield was obtained in Q26 genotype on February 10 of 4080kg.ha-1. Delayed sowing reduced yields in all genotypes.

The highest yields were obtained from Q29 and Q26 genotypes. The highest yield of these genotypes was on February 10. Also, the delay in sowing seed yield was reduced. The results of this study showed that the genotypes studied in the spring cultivation conditions had different with yield potential. Accordingly, the most optimum sowing date in terms of grain yield under climatic conditions of Kavar region in this study was planting at tenth and twentieth of February.