Investigation on the concomitant effects of water stress and foliar sprays of urea on yield and quality of Navel orange.
2008
Tadayyon, Mohammad Sa`id | Rastegar, Hamid | Kamkar Haqiqi, A`li Akbar | Fayyazi, Mas`ud | Nasr Ol-Lahi, Khandan | Jukar, Ladan
In present study the synchronous and separate effects of both urea fertilizer leaf nutrition and drought stress at different time on yield and quality of Washington navel orange (Cirus sinensis L.) in jahrom region were surveyed. Experimental factors included drought stress with three levels – without stress (control) – drought stress in mid July (Forzatura tecniqui) up to -24- -28 atmosphere leaf water potential before sunrise - drought stress in late September up to -24- -28 atmosphere leaf water potential before sunrise and urea fertilizer leaf nutrition with four levels – without urea fertilizer leaf nutrition (control) and 2% urea leaf nutrition at three deferent times i.e. mid July, late September and two weeks before blooming (late march). Trial was conducted as factorials arranged by randomized complete blocks design with three replications during two consecutive years. Each plot contains 3 trees and on the whole experiment carried out on 108 trees. Results showed that drought stress in late September had the most significant effects on the increasing of leafy flower buds and non- leafy flower bud on current season growth flashes. According to the results the enhances of Washington navel orange fruit yields means per tree was related to the increment of leafy flower buds on current season growth flashes and reduction in fruit weight has no significant effect on total fruit yields of trees. Meanwhile, fruits that reproduced from leafy flower buds had higher quality in respect to the brix of fruit juice. Results showed that drought stress treatment at late September had 17% increases on the means of fruit yields in comparison with control. On the other hand, urea spray especially before flower induction (in late September) and blooming in late March caused an enhancing, setting and reduction of non- leafy flower bud dropping on the trees.
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