JWSS - Journal of Water and Soil Science

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To determine the effects of salinity and boron excess in irrigation water on relative growth rate (RGR), net assimilation rate on a leaf weight basis (NAR), and leaf weight ratio (LWR) of pistachio, three pistachio rootstocks (Badami -Zarand, Sarakhs and Ghazvini) were used. Rootstocks were grown in soil in eight-liter polyethylene pots. Sodium chloride treatments were 0, 75,150 and 225 mM NaCl and boron treatments were 0, 20 and 40mg liter^-1. Treatments were applied to the one-year old pistachio rootstock seedlings in three-day intervals with irrigation water. Some plants were randomly selected and destructively harvested before (day 0) and after applying treatments (30 and 60 days after treatments started). Growth and physiological characters were then measured as follows: number of leaves, leaf area, plant height and root length, fresh and dry weights of stem, root and leaf, proline accumulation in the leaf, total chlorophyll, and leaf relative water content (RWC). Results indicated that relative growth rate decreased with time for all treatments and in all rootstocks. Salt treatment significantly reduced both RGR and NAR, whereas LWR showed no significant differences. In all rootstocks, NAR, but not LWR, was significantly correlated with RGR, indicating that NAR was an important factor underlying the salinity-induced differences in RGR among the pistachio rootstocks. Salinity did not affect leaf water potential (ψ), chlorophyll content, and Fv:Fm ratio but increased NaCl concentration and time correspondingly increased proline accumulation in leaves. In addition, Ghazvini rootstock accumulated more proline compared to other rootstocks and was more resistant to salinity treatments. Different boron treatments did not show any significant effect on growth rate nor on measured parameters after two months of exposure to treatments.

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This study was conducted to evaluate the effect of salinity on concentration of potassium (K), sodium (Na) and chloride (Cl) ions, in sweet lime budded on five citrus rootstocks, including Bakraii (mandarin x sweet lime), Volcameriana, Sour orange, Sweet lime and Mexican lime in a glasshouse, using a randomized completely design with factorial arrangement and four replications. Rootstocks had great effect on the concentration of ions in scion. Concentration and distribution of ions were significantly different in control and other treatments. Salinity increased Na and Cl ions in shoots and roots, but the rate of increase varied among rootstocks and treatments. Lowest concentration of Na and Cl ions were in shoot of scion on Volkameriana. Under salinity stress, K concentration increased in shoots of scion on Sour orange and Bakraei and decreased it on other rootstocks. Salinity increased K concentration in roots of all rootstocks except for Mexican lime.

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In arid and semi arid regions with high boron content in irrigation water, boron toxicity is a considerable problem. Critical levels of boron in irrigation water variy between 1 and 10 mg/l for sensitive and resistant plants, respectively. In southern parts of Iran especially large citrus production region as Jahrom and Giroft cities, high boron content in irrigation water at toxic levels in most of the region has been the restricting factor for citrus yield increase and for citrus trees exposed to intensive deficiency of potassium and micronutrients like iron, zinc and magnesium. In this experiment, the separate effects of citrus rootstocks including Macrophylla (Citrus macrophylla Wester), Volkamer lemon (Citrus volkameriana), Sour orange (citrus aurantium), Sour lime (Citrus aurantifolia Swing) and their combination with ‘Valencia’ orange, ‘Washington navel’ orange, ‘Jahrom local’ orange, red pulp orange (‘Moro’) as scions on boron uptake were studied. The experiment was conducted as factorial arranged in randomized complete block design with 5 replications and 2 trees per plot in Jahrom Agricultural Research Station for 4 years. According to experimental results, the highest level of boron uptake belonged to ‘Volkamer’ lemon and the lowest to ‘Macrophylla’ rootstocks. Although, Sour orange rootstock had the medium level of boron uptake, but the leaf boron concentration of grafted cultivars on it was clearly very high. In comparison with other rootstocks, interaction between ‘Macrophylla’ rootstock and ‘Valencia’ orange, ‘Washington navel’ orange and red pulp orange (Moro), except ‘Jahrom’ local orange as scions, caused a significant decrease to leaf boron concentration.