نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشیار بخش تحقیقات اصالح و تهیه نهال و بذر، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان خوزستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، اهواز، ایران
2 استادیار بخش تحقیقات اصالح و تهیه نهال و بذر، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی صفیآباد سازمان تحقیقات، آموزش و ترویج کشاورزی، دزفول، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Background and objective: Khuzestan province is one of the suitable region for off-seasion production. In this region potato was planted crop from mid November to mid January. Analyses of meteorological data showed that the probability of a frost occurrence is 50% from late December to late February. Therefore potato plants of different planting dates are often subjected to frost in various phonological stages, so that, yield loss will vary depending on the planting date. In fact, this experiment was conducted to evaluate the effects of planting date on yield and agronomic characteristics of potato cultivars, but frost occurrence in mid January created exceptions and special opportunity for us to study the influence of frost occurrence in different phonological stages on recovery rates and some growth indices of potato cultivars.
Materials and methods: This study was conducted on the research farm of Behbahan Agriculture Research Station from 2015 to 2016. This research was done in a split plot experiment arranged in a randomized complete block design with three replications. Planting date considered as the main plot, from 1 to to 21 December with 10 day intervals and four cultivars as sub plot (Sante, Savalan, Santana and Almera). five plants were sampled from each sub-plot from 15 days after plants emergence to harvest with 15 days interval and separated into haulms and tubers. Plant tissue was oven dried at 75ºC for 72 hours. The growth indices including haulm growth rate, tuber growth rate, crop growth rare and relative growth rate growth calculated. When the diameter of the swollen tip of stolon was twice as long as stolon diameter, considered as tuber initiation . Tubers were harvested in mid May. After harvest analysis of variance were done by MATAT-C statistical software and means were compared using Duncan’s multiple test range.
Results: When frost occurred, the phonological stages of plants in planting dates of 1 and 11 Dec. were vegetative growth and tuberization stages respectively, so that all haulms were killed, while plants in planting date of 21 Dec. didn’t emergence from soil. The yield of 11 Dec. planting date was significantly higher than 1 Dec at 5% probability level. Haulm growth, crop growth rate and relative growth rate of all cultivars were negative during the first sampling period after frost occurrence. The recovery rate of Savalan cultivar was higher as compared with other cultivars. Due to higher tuber and crop growth rate, Savalan cultivar produced the highest yield in 1 and 11 Dec. The maximum relative growth rate in planting dates of 1 and 11 Dec. were recorded for Sante and Savalan cultivars respectively. The yield of 21 Dec. planting date was significantly higher than1 and 11 Dec at 1% probability level.
Conclusion: The findings of this study suggest that to minimize the risk of yield loss by frost, planting of potato should be avoided before late January in Khuzestan province and Savalan cultivar is recommended for this area.
کلیدواژه‌ها [English]
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