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This study evaluates the effects of intercropping patterns, plant growth‐promoting rhizobacteria and arbuscular mycorrhizal fungi (AMF) on seed yield and yield components of black cumin (Nigella sativa L.) and fenugreek (Trigonella foenum‐graecum L.), as well as the essential oil and fatty acid profile of black cumin. A two‐year two‐factorial field experiment was conducted in 2015 and 2016 to investigate intercropping of black cumin and fenugreek in five ratios and biofertilizer application as AMF and bacteria. Intercropping reveals higher concentrations of nitrogen and phosphorus compared with monocropping, whereas monocropping inoculated with bacteria shows the highest seed yield of both fenugreek (151 g m−2) and black cumin (148 g m−2). Regarding the quality of black cumin, the combination of a black cumin:fenugreek‐intercropping pattern of 66:34 with bacteria fertilization is most promising, as it shows i) the maximum essential oil content, oil yield, and fixed oil content, ii) the highest contents of thymol and p‐cymene, iii) the highest content of linoleic acid, and iv) the maximum land equivalent ratio. Conclusively, bacteria fertilization and black cumin:fenugreek‐intercropping pattern of 66:34 helps improving essential oil, fixed oil quality, and quantity of black cumin, thus creating a more sustainable cultivation system for black cumin and fenugreek.

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IntroductionThe ultimate object of testing for germination is to gain information with respect to the field planting value of the seed and to provide results that can be used to compare the value of different seed lots (ISTA, 2005). However, the standard germination test often overestimates actual field emergence (Hampton, 2009). The major reason for this overestimation is that germination tests are conducted under conditions that are more favorable than typically encountered in the field. In order to provide a more accurate appraisal of seed quality for estimating field emergence, the concept of seed vigor was established to measure the quality of a seed lot, based on sampled observations of seedling growth (Sako et al., 2002).Vigor testing not only measures the percentage of viable seeds in a sample; it also reflects the ability of those seeds to produce normal seedlings under the less-than-optimum or adverse growing conditions that may occur in the field (ISTA, 2005). Low-vigor lots having poor field emergence may not necessarily be detected by standard germination (Demir and Mavi, 2008). Demir (2007a, 2007b) identified that vigor test regimens correlated well with field emergence potential.Although vigor testing provides useful information, most vigor tests are time-consuming and costly, and they produce variable results from laboratory to laboratory (Sako et al., 2002). In plants that have small seeds, such as Medicago sativa and Onobrychis viciifolia, these problems are serious and have prevented the widespread, standardized use of seed vigor testing. The vigor tests that have been proposed can be grouped into 3 categories (Bennett, 2002): stress tests (e.g., cold test, accelerated aging), biochemical tests (e.g., electric conductivity, tetrazolium test), and germination evaluation and seedling growth tests (e.g., first count of the germination test, normal seedling emergence in peat, image analysis).Accelerated aging is one of the 2 frequently used ISTArecommended vigor tests (

Astrodaucus orientalis is a weed species in cropping systems and rangelands in Iran. The effects of temperature, light, NaCl concentration, water potential, seed burial depth and crop residue cover were assessed on seed germination and seedling emergence of two populations of A. orientalis from Ardabil (Meshginshahr population) and East Azarbayjan (Tabriz population) provinces of Iran. The A. orientalis populations indicated different responses to environmental factors and burial depth. In the Tabriz population the greatest germination (88.5%) was observed in 20/12°C day/night temperature but in the Meshginshahr population (83.2%) it was obtained in 24/16°C day/night temperature. Over a broad range of light period (10–24 hr light) germination was 74–83%, but it decreased (less than 37%) under 24 hr dark in both A. orientalis populations. With respect to water potential, the C50 parameters were −0.62 and − 0.49 MPa for Tabriz and Meshginshahr populations, respectively. The D50 parameters (the burial depth that caused 50% decrease in emergence) for Tabriz and Meshginshahr populations were 2.42 and 3.13 cm, respectively. Generally, the results showed that emergence of both populations of A. orientalis was delayed as depth of burial increased up to 4 cm and in cropping systems a shallow tillage that locates the seeds to >4 cm of depth in soil could be used in order to suppress seedling emergence. Our findings also could be useful in integrated management of A. orientalis in winter annual crops and rangelands.

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Three prevalent aliphatic polyamines (PAs) include putrescine, spermidine, and spermine; they are low-molecular-mass polycations involved in many physiological processes in plants, especially, under stressful conditions. In this experiment, three bean (Phaseolus vulgaris L.) genotypes were subjected to well-watered conditions and two moderate and severe water-stressed conditions with and without spermidine foliar application. Water stress reduced leaf relative water content (RWC), chlorophyll contents, stomatal conductance (g s), intercellular CO 2 concentration (C i), transpiration rate, maximal quantum yield of PSII (F v /F m), net photosynthetic rate (P N), and finally grain yield of bean plants. However, spermidine application elevated RWC, g s , C i , F v /F m , and P N , which caused an increase in the grain yield and harvest index of bean plants under water stress. Overall, exogenous spermidine could be utilized to alleviate water stress through protection of photosynthetic pigments, increase of proline and carotenoid contents, and reduction of malondialdehyde content.