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Hollyhock (Alcea rosea L.) is an aromatic, ornamental/medicinal plant species for which the selection of drought-tolerant varieties based on physio-chemical traits is desirable. The data presented resulted from a field experiment. This experiment was designed as a split-plot, based on a randomized complete block design, in which the main plots consisted of the three irrigation regimes (30, 60 and 80% permissible discharge moisture available in the soil), and the subplots consisted of nine hollyhock varieties. Photosynthetic pigments, Fv/Fm, proline content and selected antioxidant enzymes were measured throughout the period of induced drought stress. The data obtained illustrate the nature of the physiological response of hollyhock to drought stress. Based on the measured traits the varieties Isfahan 1, Shiraz 1 and Tabriz were shown to display the highest degree of resistance to drought stress. These data suggest that the effect of drought stress is dependent upon the drought level, variety and the trait in question. In this regard, future plant breeders for this species may find it useful to utilize ascorbate peroxidase (APX), catalase (CAT) and guayacol peroxidase (POX) activities as biochemical markers to select for drought-tolerant genotypes. As such, hollyhock can be considered a promising ornamental/medicinal species for cultivation in semi-arid environments. [ABSTRACT FROM AUTHOR]

Parasitic weeds especially Phelipanche aegyptiaca decrease severely the production of canola. This study evaluated the effect of intercropping different wheat genotypes with canola on Phelipanche aegyptiaca growth. Ten wild wheat genotypes with different ploidy levels including TRI11712, TRI19322, TRI18664, TRI19652, TRI565, TRI15593, TRI12911, TRI11554, TRI17606, TRI7259P and seven cultivated bread wheats, namely: Falat, Chamran, Alamut, Baiat, Kavir, Sepahan, Alvand in addition to a canola cultivar called Zarfam were studied. The results revealed that intercropping of canola with wheat could significantly reduce broomrape growth depending on the type of wheat genotype. A significant genetic variation of allelopathic activity in wheat was observed, indicating the contribution of multiple genes conferring the allelopathic trait. TRI565 and TRI12911, TRI15593, TRI18664, TRI19652, TRI17606, TRI19322, and TRI7259 genotypes showed strong inhibitory effects and can be considered as potential allelopathic genotypes to suppress broomrape. The inhibitory potential of wild wheat genotypes was stronger than cultivated wheat genotypes. Alamut, Baiat, Alvand, Sepahan, and TRI11712 possessed strong stimulatory effects on broomrape germination. Such genotypes may be valuable as trap crops for depleting the Egyptian broomrape seed bank.

Forty safflower genotypes were grown under normal irrigation and drought stress. In the first experiment, the allelopathic potential of shoot residues was evaluated using the sandwich method. Each genotype residue (0.4 g) was placed in a sterile Petri dish and two layers of agar were poured on that. Radish seeds were placed on agar medium. The radish seeds were cultivated without safflower residues as the controls. The length of the radicle, hypocotyl, and fresh biomass weight and seed germination percentages were measured. A pot experiment was also done on two genotypes with the highest and two with the lowest allelopathic activity selected after screening genotypes in the first experiment. Before entering the reproductive phase, irrigation treatments (normal irrigation and drought stress) were applied. Shoots were harvested, dried, milled and mixed with the topsoil of new pots and then radish seeds were sown. The pots with safflower genotypes were used to evaluate the effect of root residue allelopathy. The shoot length, fresh biomass weight, and germination percentage were measured. Different safflower genotypes showed varied allelopathic potential. The results of the first experiment showed that Egypt and Iran-Khorasan genotypes caused maximum inhibitory responses and Australia and Iran-Kerman genotypes resulted in minimum inhibitory responses on radish seedling growth. Fresh biomass weight had the most sensitivity to safflower residues. The results of the pot experiment were consistent with the results of in vitro experiments. Residues produced under drought stress had more inhibitory effects on the measured traits. Safflower root residue may have a higher level of allelochemicals or different allelochemicals than shoot residue.

Valerian (Valeriana officinalis L.) is a medicinal plant, but its cultivation is restricted by weed competition. Therefore, three rates (0.75X, 1X, and 1.25X, where X is equal to the recommended dose of haloxyfop-R (methyl ester), sethoxydim, oxadiargyl, bentazon, oxadiazon, and oxyfluorfen) were applied at the 3-4 leaf stages to valerian plants. This application was done to select the herbicide type and rate for post-controlling broadleaf and grasses weeds in this species. Herbicide injury, Soil-Plant Analyses Development (SPAD) reading, number of leaves per plant, stem diameter, and fresh and dry weights were determined 10, 20, and 30 days after herbicide application. Oxyfluorfen application caused the most herbicide injury followed by bentazon. Injury increased as the rate and the days after application increased. Oxadiazon only caused significant damage 30 days after application under all three rates. Other treatments showed no marked injuries under any rate or date after application, as compared with the control. Effects on other measured traits depended on the trait, herbicide, and herbicide rate. The highest SPAD, leaf number, shoot diameter, fresh weight and dry weight, was recorded under application of 30 mg a.i. ∙ kg-1 soil oxadiargyl and 90 mg a.i. ∙ kg-1 soil oxadiazon, 81 mg a.i. ∙ kg-1 soil haloxyfop-R, 37.5 mg a.i. ∙ kg-1 soil oxadiargyl, 22.5 mg a.i. ∙ kg-1 soil oxadiargyl, 81 mg a.i. ∙ kg-1 soil haloxyfop-R, and 81 mg a.i. ∙ kg-1 soil haloxyfop-R, respectively. To sum up, the results showed that sethoxydim, oxadiargyl, and haloxyfop-R produced no significant symptoms of phytotoxicity or reduction of measured traits. This means that oxadiargyl, haloxyfop-R, and sethoxydim may be used safely for weed control of valerian at the rates used in this experiment under similar conditions.

In Iran, Descurainia sophia, Malcolmia africana, and Thlaspi arvense are abundantly found as importunate weeds in winter cereal. Understanding the timing of seed germination under natural conditions is crucial for learning how to manage these annual weeds. Therefore, this study was conducted to evaluate the effect of soil burial, dry storage, cold stratification, KNO3, GA3, and scarification on the seed dormancy and germination of these three species. Species had significantly different responses to the treatment. In D. sophia, seeds buried at a depth of 10 cm for 60 days (55%), and seeds dry stored at 20°C for 180 days (45%) showed the highest level of germination. In M. africana, the germination percentage reached 95% when seeds buried at a depth of 1 cm were soaked in a GA3 concentration of 150 ppm. T. arvense had the lowest level of germination compared to the other species. The highest percentage of T. arvense germination was obtained in seeds treated with 150 ppm GA3. Potassium nitrate partly increased germinability in seeds of M. africana, which initially were less dormant than those of T. arvense and D. sophia.

Impact of nitrogen (N) supply on photosynthesis and N, P, and K status of wheat, particularly ancient wheats lacks clarity. Hence, clarification of post-anthesis photosynthesis and N, P, and K status of ancient emmer compared to the improved durum and bread wheats was aimed at. Five field-grown ancient emmer, one improved durum and an improved bread wheat exposed to a wide range of N fertilizer (i.e. 0, 25, 50, and 75 kg ha−1 N) were tested in two consecutive years. Chlorophyll and carotenoids concentrations of the emmer and improved wheats were increased by 39–63% and 29–45%, respectively in response to N supply. Mesophyll conductance and net photosynthetic rate of the improved bread wheat were increased by 150% and 60%, respectively, with increase in N supply, but those of the emmer wheats were decreased in response to the medium (0–43%) and high N (0–37%) supplies. Emmer wheat out-numbered the improved wheats in terms of mesophyll conductance and net photosynthetic rate under the low N supply but the reverse was true with the high N supply. Leaf (1–2.2, 3.2–7.7, and 16.8–35 mg g−1, respectively) and grain (2.38–6.4, 5.6–12.1, and 20.5–28.9 mg g−1, respectively) P, leaf N, and grain K concentrations responded positively to the N supply and emmer wheats equaled or exceeded those of the improved wheats particularly when grown in the absence of high N supplies. The presented data indicates that ancient emmer wheats are potent to be employed to incorporate nutrient-acquiring traits into the modern wheats. [ABSTRACT FROM AUTHOR]

Egyptian broomrape is a root holoparasitic plant that causes severe damage to tomato in Iran. Experiments were conducted in 2013 to investigate the effect of silicon (Si) nutrition on broomrape response in tomato. Si concentration significantly delayed first appearance of broomrape and decreased number of tubercles in both cultivars, although the magnitude of reduction varied with cultivar and Si concentration. Broomrape infection significantly decreased root and shoot dry weights of tomato cultivars. However, Si nutrition at high concentration considerably reduced damage severity of broomrape compared to the treatment that received no Si. Infection of tomato with broomrape resulted in significant increase in peroxidase and catalase activity in the roots of resistant cultivar which led to enhanced crop resistance to oxidative stress and improved growth in this cultivar. [ABSTRACT FROM PUBLISHER]