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Drought stress is considered as a main restriction to have the best potential crops performance in arid and semi-arid regions in the world. Hence, some mechanistic strategies are required to manage drought stress detrimental influences. Silicon as an essential mineral nutrient, plays an important role in physiology, metabolism, and function of crops exposed to drought stress. This study was carried out to evaluate the influences of various irrigation regimes and silicon foliar on three safflower cultivars to find the optimal irrigation level and silicon fertilizer. Three levels of irrigation (0, 2 and 4 times irrigation during growth) were main plots and sub plots were three silicon foliar levels (0, 1 and 2 mM) and three safflower cultivars (Goldasht, Padideh and Golmehr). This experiment was performed in Firouzabad city, Fars Province, Iran with latitude 28°51' N and longitude 52°36' E, during 2018 and 2019. Malondialdehyde content (MDA), polyphenol oxidase (PPO), superoxide dismutase (SOD) and ascorbate peroxidase (APX), oil yield, oil content and seed yield were measured on these cultivars. Interactive effects of irrigation, silicon and cultivars were significant (p

Drought stress is one of the most serious limitations for the growth and yield of wheat worldwide. Under changing climatic conditions, understanding the urea fertilizer requirement for wheat could be helpful for improving the quality and quantity of yield. The effects of different urea fertilizer levels were evaluated for some biochemical and physiological properties of four wheat cultivars under two irrigation regimes. This experiment was conducted in a split-split plot, randomized complete block design, with three replications. The main plots were irrigation (normal irrigation and irrigation terminated at the stem elongation stage). The experimental plots employed four wheat cultivars (‘Shirudi’, ‘Chamran’, ‘Chamran 2’, and ‘Sirvan’) and four levels of urea fertilizer treatment (0, 120, 240, and 360 kg ha−1), at two locations, Khodayan (52°20' E, 29°8' N) and Nasrabad (52°64' E and 29°58' N), Fars Province, Iran. Results from the full analysis of variance across the two locations indicated considerable differences in yield parameters between irrigation, rates of urea application, and cultivars (p < 0.01). Interaction effects of location, irrigation, cultivars, and urea levels were also significant for Chl b, 1,000-seed weight, and seed yield (p < 0.01). The data indicated that termination of irrigation led to a reduction in RWC (20%), total chlorophyll content (30%), carotenoids (19%), 1,000-seed weight (18%), grain yield (29%), and a promotion in ionic leakage (17%) and proline accumulation (4%), in comparison to the controls. According to these results, ‘Chamran’ and ‘Shirudi’ showed the greatest tolerance to reduced irrigation and that using 240 kg ha−1 urea may effectively moderate the adverse effects of this in these and other wheat cultivars.

EFEITO DE NANO-QUELADO DE NITROGENIO E UREIA FERTILIZANTE EM PLANTAS DE TRIGO SOB CONDICOES DE ESTRESSE HIDRICO Este estudo foi realizado para avaliar os efeitos de nitrogenio nano-quelatado e ureia fertilizante em plantas de trigo sob condicao de estresse hidrico. Foram realizados experimentos em dois locais na provincia de Fars, no Ira. O delineamento experimental adotado foi em parcelas subdivididas no modelo RCBD. O primeiro fator incluiu os tratamentos de irrigacao (irrigacao normal e retencao na fase de floracao), o subfator foi o tratamento com nitrogenio (0, 37, 74 e 110 kg ha-1) na forma de fertilizante ureia e sub-subfator foi nitrogenio (0, 14, 27 e 41 kg ha-1) na forma de adubo nitrogenado nano-quelatado. As caracteristicas morfometricas estudadas foram o peso da haste, peso da espiga, comprimento da espiga, altura da planta, numero do perfilho, diâmetro do caule, antocianina, flavonoides, prolina, carboidratos soluveis, clorofila aeb, carotenoides, peso de 1.000 sementes, rendimento biologico, produtividade e indice de colheita. De acordo com a analise de variâncias, o estresse hidrico, o nitrogenio (ureia) e o nitrogenio nano-quelatado apresentaram efeitos significativos em todas as caracteristicas agronomicas estudadas. De acordo com comparacoes de medias, o estresse hidrico levou a uma reducao de 51% no rendimento de sementes em comparacao com a irrigacao normal. A aplicacao de 37, 74 e 110 kg ha-1 de ureia levou a um aumento de 9, 19 e 27% no rendimento de sementes em relacao ao controle, respectivamente. A aplicacao de 14, 27 e 41 kg ha-1 de nano-quelatado levou a um aumento de 31, 44 e 98% no rendimento de sementes em comparacao com o controle, respectivamente. Na interacao entre estresse, ureia e nano fertilizante na produtividade das sementes, verificou-se que nas condicoes normal e de estresse a maior media de produtividade de graos (7591 e 4091 kg ha-1) foi obtida em 110 kg ha-1 de ureia e 41 kg ha-1 adubo nano. Em conclusao, substituindo a ureia por nitrogenio nano-quelatado pode aumentar o rendimento, mesmo no estresse hidrico e diminuir a quantidade de fertilizante necessario.Palavras-chave: caracteristicas agronomicas, caracteristicas bioquimicas, irrigacao, produtividade de sementes. ABSTRACT: This study was performed to evaluation of nano chelated nitrogen and urea fertilizers on wheat plant under drought stress condition. Experiments were carried out in two locations in Fars province, Iran. Experimental design was performed as split-split plot in RCBD design. The first factor included irrigation treatments (normal and withholding irrigation at flowering stage), sub factor was nitrogen treatment (0, 37, 74 and 110 kg.ha-1) in the form of Urea fertilizer, and sub-sub factor was nitrogen (0, 14, 27 and 41 kg.ha-1) in the form of nano chelated nitrogen fertilizer. Studied traits included stem weight, spike weight, spike length, plant height, tiller number, stem diameter, anthocyanin, flavonoid, proline, soluble carbohydrates, chlorophyll a and b, carotenoid, 1000-seed weight, biological yield, seed yield and harvest index. According to analysis of variances, stress, nitrogen (urea) and nano chelated nitrogen had significant effects on all studied traits. According to mean comparisons, drought stress led to 51% reduction in seed yield compared to normal irrigation. Application of 37, 74 and 110 kg.ha-1 urea led to 9, 19 and 27% increase in seed yield compared to control, respectively. Application of 14, 27 and 41 kg.ha-1 nano fertilizer led to 31, 44 and 98% increase in seed yield compared to control, respectively. In interaction between stress, urea and nano fertilizer on seed yield, was found that at normal and stress condition the highest mean of seed yield (7591 and 4091 kg.ha-1) was obtained by 110 kg.ha-1 urea and 41 kg.ha-1 nano fertilizer. In conclusion replacing urea by nano chelated nitrogen can increase the yield even in the drought stress and decrease amount of needed fertilizer. Keywords: agronomic traits, biochemical traits, irrigation, seed yield.

Drought stress is one of the most important non-viable tensions that can lead to a serious decline in plant crop, depending on the season and time it occurs. One of the ways to achieve sustainable agricultural goals is to use microorganisms that play an important role in supplying plant nutrition. This study was conducted to evaluate the physiological response of corn to pre-treatments of growth regulator and mycorrhiza under drought stress conditions in 2015 in two separate plots under a split plot based on a randomized complete block design with three replications in Fars province. The factors studied included drought stress (control, stress at the end of vegetative growth, tension in the middle of reproductive growth), mycorrhiza (control, use of mycorrhiza and mycorrhiza with half the recommended amount of phosphorus fertilizer) and growth regulator pretreatment (control, water to the results of this experiment showed that severe drought stress reduced the index of crop growth rate, relative water content of leaves and remobilization. Also, severe drought stress increased and decreased the contribution of re-transfer to poor and rich soils, respectively, than the control. The comparison of mycorrhizal effects showed that mycorrhiza with phosphorus and control had the highest and lowest crop growth index and leaf relative water content, respectively. Comparison of the average salicylic acid effect on crop growth index and relative leaf water content showed that consumption of 750 μM saltsilic acid increased both indexes compared to control. Comparison of the average effect of mycorrhiza on remobilization showed that mycorrhiza consumption and mycorrhiza + phosphorus consumption in poor soils and consumption of mycorrhiza + phosphorus and control in rich soils had the highest and lowest amount of remobilization, respectively. Also, the comparison of the average effect of mycorrhiza on the remobilization share showed that the control and consumption of mycorrhiza+ phosphorus had the highest and lowest numerical value, respectively.