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A pot experiment was carried out during two successive seasons (2014 and 2015) at Salinity and Alkalinity Soil Research Laboratory in Alexandria. The goal of this work was to study the response of rosemary (Rosmarinus officinalis L.) plants irrigated with saline water at 0, 2000 and 4000 ppm NaCl to the application of antistress agents (salicylic acid "SA" at 0 and 0.2 mM and diatomaceous earth "DDM" at 0 and 6 g/10 kg soil). The effect of these antistress agents on the vegetative growth, volatile oil percentage and its chemical composition were recorded. In general results indicated that irrigation with saline water and antistress agents (DDM and SA each of them solely) had a significant effect on vegetative growth expressed as plant height, number of branches/plant, herb fresh and air dry weights and volatile oil percentage as compared to control in most treatments in both cuts of the two seasons. Moreover the plants received diatomaceous earth (DDM) at 6 g/10 kg soil combined with irrigation with non saline water (tap water) recorded the highest values of vegetative growth and volatile oil percentage in both seasons at the two cuts. Also the highest camphor content was achieved with this treatment. Proline content was decreased with increasing the rate of diatomaceous earth followed by salicylic acid, this refers to the response of rosemary plants grown under salt stress to the application of antistress agents (DDM and SA).

I NCREASING competition on water resources between the agriculture sector and other sectors requires new irrigation regimes to perform relevant levels of production in semi-arid regions. Field experiment was conducted during two successive seasons at the Experimental Farm of EL-Quassassin, Ismailia Governorate, Egypt. This experiment was prepared to assess the effects of different irrigation intervals, potassium phthalate and their combinations on the growth, number of umbels, fruit yield,water use efficiency, and volatile oil production of fennel plant during two successive seasons 2016/2017 and 2017/2018, respectively. Three irrigation treatments, main factor, as follow: I 1 (every three days, which is the common in this region with 1150 m 3 /ha), I 2 (every five days with 766 m 3 /ha), and I 3 (every seven days with 383 m 3 /ha), and the potassium phthalate as subsidiary factor (0, 400,500, and 600 ppm) were applied. The results showed that, the highest vegetative growth parameters were related to the potassium phthalate at the rate of 600 ppm and irrigation interval 3 days.The highest values of fruit yield, as well as the volatile oil production were significantly affected by the potassium phthalate and irrigation frequency in both seasons. Nevertheless, the concentrations of the macro and micro-nutrients in fruits revealed an increasing trend with increasing the irrigation intervals.In addition, the lower the amount of water use, the higher the water use efficiency.The results of GLC analysis of fennel volatile oil indicated that methyl chavicol as the main component varied between (63.02 and 80.82%). The treatment of potassium phthalate at 600 ppm with irrigation every 3 days resulted in the lowest methyl chavicol percentage.Thus, the proper irrigation interval increases the plant water stress tolerance by increasing the water use efficiency and the nutrient concentrations of fruits.

This study was carried out during 2012 and 2013 seasons at the experimental farm of Medicinal and Aromatic Plants Research Department in El-Kanater El-Khairia. The investigation aimed to study the effect of irrigation at 25, 50 and 100% from field capacity (FC) combined with diatomaceous earth (DDM) at 0, 2 and 4 g/10 kg soil in order to regulate water irrigation and to study their effect on vegetative growth and volatile oil production of spearmint plants (Mentha viridis L.). The obtained results are summarized as follows: in all cuts in the two seasons, the plants received DDM at 4 g/10 kg soil + 100% FC, showed stimulation in growth characters, i.e plant height, branching, fresh and dry weights of spearmint plants. Although the highest volatile oil percentage/plant through the two seasons was achieved when the plants were treated with 25% and 50% FC but the volatile oil yield was the highest at 4 g DDM /10 kg soil + 100% FC. The highest percentage of Carvone (the main component of the volatile oil) was produced with 4 g DDM/10 kg soil +100% FC. Proline content was decreased with increasing irrigation and diatomaceous earth rate, this refers to response of mint plants to treated by diatomaceous earth with the irrigation at 50% or 100% FC and not exposed to stress at 25% FC compared to the control (the highest proline content).