In the Mediterranean basin, olive cultivation occupies the largest share of agricultural land, due to the region’s favorable soil and climatic conditions. However, the intensification of farming systems has had negative environmental impacts, for which diversified approaches such as agroforestry offer a potential solution. The objective of the present study was to determine the growth of barley, triticale, and pea as cover crops, as well as the respective intercrops in olive orchards and their productivity. The results showed that the intercropping of pea with barley and triticale had the highest yields in dry biomass compared to the other treatments, while barley monoculture recorded the highest yield in terms of grain. The findings demonstrated that intercropping enhances resource-use efficiency, particularly in terms of land productivity, Radiation-Use Efficiency, and Water-Use Efficiency. However, competitive dynamics varied significantly between species and across years, with pea often exhibiting dominance in biomass production, while cereals showed trade-offs in seed yield components due to shading and interspecific competition. These findings can be used for sustainable intensification strategies, ensuring higher productivity while minimizing external inputs in climate-vulnerable regions.

The term intercropping is used to describe agricultural systems where at least two or more species are cultivated in the same field for a portion of their biological cycle. It is an ancient agricultural practice that, with the evolution of agriculture, the prevalence of intensive cultivation systems, and the use of multiple inputs became mostly restricted to developing countries. However, due to climate instability and uncertainty about weather conditions, interest in intercropping has been revived in recent years. The objective of the present study was to determine which faba bean cultivar can be used with wheat cultivars to achieve higher yields and to examine the interaction between the cultivars in intercropping systems. It was found that the combination of Flamenko with Polycarpi gave the highest yield and showed complementarity in the interaction between these cultivars that also have the highest yield; also, the other indices that were used showed a good response on the intercropping system and the LER was 1.30 and 1.19 for the first and the second year of the study, respectively. Therefore, there are faba bean and wheat cultivars that are better adapted to intercropping conditions and can be utilized by farmers to enhance productivity.

Intercropping is the cultivation of two or more crop species in the same space for a considerable proportion of the growth period. Farmers use cultivars that were bred under monoculture and there are no cultivars that have been evaluated under intercropping systems. The objective of the present study was to evaluate different cultivars of pea and wheat on intercropping systems. The experiment was conducted for two successive growing seasons (2018–2019 and 2019–2020) at the University Farm of Aristotle University of Thessaloniki, Greece, using two cultivars of field pea and six cultivars of bread wheat, and all their mixture combinations. The growing seasons, the intercropping treatments, and the cultivars affected the grain yield, the yield components, and the land equivalent ratio (LER) and actual yield loss (AYL) values. The different cultivars showed different responses under the intercropping treatments, indicating that there are cultivars that show higher grain yield in mixtures. Based on the mean grain yield for both growing seasons, the mixture ‘Isard’–‘Mavragani’ showed higher grain yield by 86.5% and 55.7% compared with the mean grain yield of all other mixtures and monocultures, respectively. The total LER value of ‘Isard’–‘Mavragani’ was high in both years: 1.954 and 1.693 in 2018–2019 and 2019–2020, respectively. This multicriteria evaluation of winter wheat and field pea varieties exhibited the need for the selection of appropriate cultivars for intercropping systems that were previously assessed under intercropping conditions before their exploitation from the farmers.

Lentil is a versatile and profitable pulse crop with high nutritional food and feed values. The objectives of the study were to determine suitable locations for high yield and quality in terms of production and/or breeding, and to identify promising genotypes. For this reason, five lentil genotypes were evaluated in a multi-location network consisting of ten diverse sites for two consecutive growing seasons, for seed yield (SY), other agronomic traits, crude protein (CP), cooking time (CT) and crude protein yield (CPY). A significant diversification and specialization of the locations was identified with regards to SY, CP, CT and CPY. Different locations showed optimal values for each trait. Locations E4 and E3, followed by E10, were “ideal” for SY; locations E1, E3 and E7 were ideal for high CP; and the “ideal” locations for CT were E3 and E5, followed by E2. Therefore, the scope of the cultivation determined the optimum locations for lentil cultivation. The GGE-biplot analysis revealed different discriminating abilities and representativeness among the locations for the identification of the most productive and stable genotypes. Location E3 (Orestiada, Region of Thrace) was recognized as being optimal for lentil breeding, as it was the “ideal” or close to “ideal” for the selection of superior genotypes for SY, CP, CT and CPY. Adaptable genotypes (cv. Dimitra, Samos) showed a high SY along with excellent values for CP, CT and CPY, and are suggested either for cultivation in many regions or to be exploited in breeding programs.

Intercropping is the simultaneous cultivation of two or more crops species in the same space for a considerable proportion of the growth period. Intercropping has several advantages and is used in both traditional and sustainable agriculture. The objective of the present study was to study the interactions among different pea and wheat cultivars and the effect of water availability on wheat-pea mixtures and the competition between the two species. The experiment was conducted for two successive growing seasons using two different irrigation regimes and two cultivars from each species. The different treatments were evaluated using morphological and agronomic characteristics. Intercropping treatment, cultivars, and irrigation level affected most of the characteristics that were studied and the competition between the two species. Biomass was higher by 47% and leaf area index by 34% under irrigation compared to the rainfed conditions. The different cultivars showed different response under the two water regimes. Based on the intercropping indices, the mixture ‘Yecora E’ - ‘Isard’ is favoured under irrigation while the combination ‘Elissavet’ - ‘Isard’ under low water availability. There was interaction between cultivars and irrigation and using different cultivars in intercropping can have higher yield advantage than monocropping by exploiting the environmental resources more efficiently. Therefore, the use of appropriate cultivars in mixtures can affect the growth, biomass yield and competition between the two species leading to higher yield and greater economic return.

The 4C approach considers intercropping performances as the result of joint 4C effects. ● Partial land equivalent ratios indicate which effect(s) are the major one(s). ● A major effect of complementarity is related to a better capture of abiotic resources. Modern agriculture needs to develop transition pathways toward agroecological, resilient and sustainable farming systems. One key pathway for such agroecological intensification is the diversification of cropping systems using intercropping and notably cereal-grain legume mixtures. Such mixtures or intercrops have the potential to increase and stabilize yields and improve cereal grain protein concentration in comparison to sole crops. Species mixtures are complex and the 4C approach is both a pedagogical and scientific way to represent the combination of four joint effects of Competition, Complementarity, Cooperation, and Compensation as processes or effects occurring simultaneously and dynamically between species over the whole cropping cycle. Competition is when plants have fairly similar requirements for abiotic resources in space and time, the result of all processes that occur when one species has a greater ability to use limiting resources (e.g., nutrients, water, space, light) than others. Complementarity is when plants grown together have different requirements for abiotic resources in space, time or form. Cooperation is when the modification of the environment by one species is beneficial to the other(s). Compensation is when the failure of one species is compensated by the other(s) because they differ in their sensitivity to abiotic stress. The 4C approach allows to assess the performance of arable intercropping versus classical sole cropping through understanding the use of abiotic resources.

Intercropping is an old and commonly used agricultural practice and involves the cultivation of two or more crops in the same area of land at the same time and may improve yield, the use of the environmental resources, product quality, and soil health. The objective of the present study was to study the effect of water availability of wheat-pea intercrops using agronomic and physiological characteristics. The experiment was conducted at the farm of Aristotle University of Thessaloniki, Greece during two growing seasons 2017–2018 and 2018–2019 using two different cultivars from pea (Isard and Olympos) and wheat (Yecora E and Elissavet) and two irrigation regimes. The availability of water increased grain yield and affected most of the characteristics that were studied. In terms of total Land Equivalent Ratio (LER) there was a yield advantage of intercrops over monocrops, which indicates the efficiency of intercropping for using the environmental resources. Both wheat cultivars, the pea cultivar Olympos and their intercrops indicated high adaptation capacity to rainfed conditions, whereas Isard and its intercrops performed better under irrigation. Therefore, the intercropping of wheat with pea uses the water resources of the environment more efficiently and can be used in dry land conditions for higher yield.

Plant yield efficiency (PYE) reflects the ability of the single-plant to respond to additional inputs and is fully expressed at the nil-competition regime (an ultra-low density to preclude inter-plant interference for inputs). The purpose of this study was to determine if PYE could prevent the erratic optimum plant density-yield interaction effect in maize (Zea mays L.). Seven hybrids were evaluated across five environments at four densities, under both the normal-input regime (NIR) and low-input regime (LIR). Plant yield efficiency was measured at the lowest density approaching the nil-competition regime (0.74 plants m(-2)), while crop (per area) yield potential was estimated at the highest density corresponding to the typical farming density in the NIR (8.89 plants m(-2)). In terms of optimum density, the hybrids varied extensively in the NIR (6.64-8.81 plants m(-2)) but performed similarly in the LIR (5.11-5.61 plants m(-2)). The hybrid displaying the highest PYE also had high harvest index (HI) and low anthesis to silking interval (ASI) and was proved the most stable according to various stability statistics including the genotype and genotype by environment (GGE) biplot model. In conclusion, crop yield by density interaction is a matter of hybrid. Hybrids with low PYE have inconsistent optimum density, which is a causal factor of yield loss in rainfed maize. High PYE improves hybrid flexibility and performance at low densities ultimately enhancing crop resilience to extremely fluctuating environments.

Liquid dairy cattle (Bos taurus) manure effect on corn (Zea mays L.) yield and nutrients’ uptake and soil fertility were studied, in comparison to the crop’s common and recommended inorganic fertilization, by means of a 5-year field experiment. The treatments applied each year in the same plots were: (i) manure, (ii) common inorganic fertilization, (iii) recommended inorganic fertilization, and (iv) no fertilization. Each year from each plot, surface soil samples were collected before sowing, corn aboveground biomass was collected at silage, they were analyzed, and grain yield was determined at harvest. Upon all kinds of fertilization, corn silage yield increased in comparison to control and ranged between 51 and 194, 50 and 190, and 39 and 189% for the manure, recommended, and common inorganic fertilization treatment, respectively. Similarly, grain yield and the macro- and micronutrients’ plant uptake were increased. Soil fertility improved regarding the NO3-N, which upon organic or inorganic fertilization increased 10–46% in comparison to the control. Manure application significantly increased K by 32–81%. However, in the case of P, an excessive increase was observed, which was two to three times higher than the inorganic fertilization (30–44 mg kg−1). Consequently, repeated annual applications of liquid cattle manure to soil can enhance crop yield, nutrients’ uptake, and soil fertility, at levels higher or similar to the common or recommended inorganic fertilization for the crop. However, the possibility of P build up should also be considered.

Intercropping is an eco-friendly agricultural practice for achieving higher quantity and quality of forage crops. The present study was aimed to evaluate the forage quality, quantity and ecological indices (monetary and competition) of maize in intercropping with different legumes at two different growing years (2017–2018) in the north west of Iran. The treatments were monoculture of two maize hybrids (KSC301 and KSC704), grasspea (Lathyrus sativus L.), berseem clover (Trifolium alexandrinum L.), bitter vetch (Vicia ervilia L.), hairy vetch (Vicia villosa L.) and additive intercropping of two maize hybrids with the above mentioned legumes. The highest and lowest total forage yield and crude protein yield (CPY) was achieved in intercropping of KSC301 with hairy vetch and maize monocultures. Also, the highest value of total digestible nutrients (TDN), dry matter digestibility (DMD), dry matter intake (DMI) and net energy for lactation (NEl) was observed in intercropping of KSC301 with grasspea. In addition, acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents in maize monocultures increased by 19% and 29% compared with intercropping patterns. Averagely, the highest RVT was calculated in the intercropping of KSC301 with grasspea and KSC301 with hairy vetch. The maximum LER was achieved in intercropping of KSC301+ hairy vetch and KSC704+ hairy vetch. Generally, based on the forage quantity, quality and monetary indices, intercropping of KSC301 with grasspea and KSC301 with hairy vetch was superior to maize monocultures and can be suggested, as an eco-friendly and cleaner production method, to farmers instead of monoculture systems.

Three oat (Avena spp.) and three field pea [Piston sativum subsp. arvense (L.) Asch.] cultivars were grown in pure stands and interspecific, binary mixtures under Mediterranean conditions for two growing seasons (2011-12 and 2012-13). The aim of the work was to identify traits contributing to the complementary use of soil nitrogen (N) and water in intercrops. Such traits could be used as putative selection criteria for cultivars well-adapted to intercropping systems. The N-15 natural abundance method was used to assess the percentage of N derived from N-2-fixation (%N-dfa) in pure stands and intercrops and the percentage of N transferred from pea to oat (%N-trans) in intercrops. Carbon isotope discrimination (Delta(pea), Delta(oat)) was used as an assessment of water use efficiency. Isotope determinations were conducted when 30% of pea flowers were open. Dry matter yield (DM) of pure stands and intercrops was estimated at forage silage maturity of peas, and forage quality traits (protein, fat, ash, crude fiber, and nitrogen free extracts concentrations) were measured. Intercropping either increased or decreased %N-dfa depending on the cultivars included in the mixtures. High %N-dfa by pea in mixtures was associated with a high contribution of pea in the mixture and high crude protein concentration in DM. High amounts of fixed N and N accumulated in pea were necessary to maximize protein concentration and protein yield in intercrops. These amounts were calculated to be 72.0 and 94.4 kg N h(-1) for protein concentration and 124.2 and 160.8 kg N ha(-1) for protein yield. Oats in intercrops seemed to affect the N niche of peas. Delta(oat) values were positively correlated with %N-dfa, the amount of fixed N in pea and the amount of N accumulated in pea. A plausible explanation for this is that high Delta(oat) values were indicative of a better access to soil water and nitrate (NO3-N) sources through a deeper and denser rooting system, thus increasing the competition on the companion pea which led to higher percentage of N-2-fixation and consequently to higher amounts of N fixed by and accumulated in pea. High-Delta oats were less dependent on N transferred from pea as was indicated by a negative correlation between these two traits. As a consequence, high Delta(o)(at) values were associated with high protein concentration and protein yield. In contrast, Delta(pea) values were negatively correlated with protein concentration and protein yield. Peas, having a less competitive rooting system compared to oats, were adaptive to intercropping when they had a more conservative use of soil water (lower Delta(pea)), and thus avoided competition. Land equivalent ratios for dry matter yield (LERDM) and protein yield (LERCPY) were affected by growing seasons. LERDM was < 1.00 (0.88) in 2012-13 growing season indicating that intercropping was not favored. This season was characterized by lack of precipitation during December 2012 and January 2013, high precipitation in February ( > 62% of season's water input) and mild temperatures during winter (November to February). The very early, moderately tall oat cultivar Flega had the highest LER values, regardless of the companion pea cultivar. This was an indication that Flega was favored by growing in intercrops, however, Flega's mixtures were not among the high-yielding mixtures.

Doubled-haploid is an effective method to produce 100% homozygous lines in asingle generation accelerating the release of new varieties and reducing thecorresponding expenses. However, the existing problem in cases where theadequate quantity of seeds is limited is the inability to evaluate new germplasm inreplicated experiments. In his attempt to confront this problem, Petersen proposedin 1985 the evaluation of new germplasm to be based on its division in blocks andselection to be performed regarding the yield of the randomly repeated control ineach block. The aim of the present study was to use the aforementioned method toevaluate preliminary 37 doubled-haploid lines (DHL). The parental varieties of theDHLs,Greek cultivars “Acheloos” and “Vergina”, were used as controls. For thepurpose of the study, 35 main spikes, one form each DHL and control, were used.The length of the spikes was measured, the number of spikelets was counted, andthe 1000 kernel weight and total yield were recorded. The data analysis revealedthat only one line exceeded the mean number of spikelets of the controls, oneexceeded the mean yield of the controls and two exceeded the mean 1000 kernelweight of the controls (one was even better than the best control). The reportedresults indicate the presence of valuable genetic variability among the DHL aftercrossing cultivars “Acheloos” x “Vergina”. Further research is needed, after DHLsmultiplication, using more plants and locations to draw more reliable conclusions.

Reducing interspecies competition and enhancing complementarity through cultivar selection in intercrops is important for achieving sustainable intensification. Under Mediterranean conditions, pea-oat intercrop has shown high land-use efficiency (LER). Field experiments were established under rainfed conditions in two locations in Greece for two growing seasons (2011-12 and 2012-13) to assess agronomic traits [date to flowering, plant height at stem elongation BBCH32, fmal plant height, and lodging], dry matter yield (DM), quality traits (protein, fat and ash concentrations, nitrogen free extracts), crop protein yield (CPY), and the competitive ability of three oat and three field pea cultivars in intercrops and Sole crops. The intercrops produced on average 6.7% less DM than the oat sole crops, but had 27% higher CPY. However, interactions were found for the DM between the two locations, regarding species, cultivars and cropping systems, indicating that cultivars performed differently in sole crop and intercrops. Across locations, a pea-oat combination was the most consistent, showing the highest values of LER and monetary advantage index (MAI) that indicated its wide adaptation. Moreover, a second pea-oat combination showed specific adaptation to the warm and soil N-poor location. One testing environment favoured the high competitive ability of peas, whereas the other favoured the oat, possibly due to higher N-NO3 availability. Intercropped oat flowered later, was shorted at the stem elongation stage, and lodged more than sole crops. On the other hand, peas flowered later and were taller at stem elongation stage, as well in final plant height in comparison to their peers in sole crop. Overall, the results highlighted the need of multi environment trials to assess the effects of genotype x environment interactions in order to select compatible cultivars for maximizing the productivity and stability of the pea-oat intercrops.

Water stress is one of the most important environmental stresses around the world for many crop species and especially for maize. In addition, climate changes and increasing population pose serious challenges to crop improvement for increasing crop yield. Tolerance to drought is a complex quantitative trait controlled by several small effect genes or QTLs and is often confounded by differences in plants phenology. The present study aimed to investigate the tolerance of inbred lines and their correspondent hybrids using agronomic and physiological characteristics. Therefore, we used thirty one maize inbred lines under ultra-spaced and highly dense conditions and under two different water regimes (normal and drought conditions) in three different areas in Greece during the 2012 growing season. After the first year of experimentation the inbred lines were divided into three different groups tolerant, moderate sensitive and sensitive to water stress and specific hybrids from the combination of the different groups were evaluated under two water regimes and under ultra-spaced and highly dense stands and in three locations during the 2013 growing season. The inbred lines and the hybrids were evaluated using a number of physiological (gas exchange parameters, chlorophyll meter readings, chlorophyll fluorescence, water potential, relative water content) and agronomic traits (grain yield, harvest index and yield components). The results showed that assimilation rate was reduced by the water stress at all locations and in inbred lines and also in hybrids. In addition, harvest index, instantaneous water use efficiency, and anthesis to silking interval were affected by the water stress in both the inbred lines and the hybrids. There was a clear sign that some physiological and agronomic characteristics can be used for the selection of stress-adaptive genotypes and may allow the development of new maize hybrids from specific crosses that can be grown under different conditions addressing the climate change scenarios.

Drought is a major cause of yield loss for many important crops including maize. Therefore, the development and release of drought tolerant varieties that will yield well under a broad range of environmental conditions is an important breeding goal. Several stress indices have been developed, aiming to assist identification and selection of stable, high-yielding, drought tolerant genotypes. A novel equation (B value) that predicts crop yield potential of a genotype at normal farming densities has been also suggested1. The estimation of B value relies on plant yield potential at ultra-low densities and on the coefficient of variation (CV) of individual plants. The present study aimed to investigate the tolerance of inbred lines and their correspondent hybrids using stress tolerant indices and compare them with the B values. Therefore, we used thirty one maize inbred lines and their correspondent hybrids under ultra-spaced and highly dense and under two different water regimes (normal and drought conditions) in three different areas in Greece during the 2012 and 2013 growing season, respectively. The inbred lines and the hybrids were evaluated using grain yield and for each genotype, B value and nine other stress indices based on their yield under normal and water stress conditions were calculated, including stress susceptibility index (SSI), mean relative performance (MRP), stress tolerance (TOL), mean productivity2 (MP), relative efficiency index (REI), stress tolerant index3 (STI), geometric mean of productivity (GMP), yield index (YI) and harmonic mean4 (HM). It was found a strong and positive correlation (P<0.001) of B values with all indices, except SSI, for all experimental locations. These results suggest that B value matches the ability of the other stress indices to identify drought sensitive and tolerant genotypes and is an effective selection criterion for high yielding genotypes with stable performance under variable environmental conditions.

Plant yield efficiency reflects the single‐plant yield at low density that precludes interplant interference for resources. The role of plant yield efficiency in adaptation to water deficit was investigated in maize ( Zea mays L.). Also investigated was whether yield of space‐planted environments is transferable to densely seeded situations. Further, the correlation and genotype by environment (G × E) interaction of spaced and densely seeded plots were investigated. Thirty‐one lines and 31 crosses among them were tested in three locations under dense stand and the ultra low density of 0.74 plants m −2 as well as in normal and deficit irrigation treatments. The dense stand was 4.44 plants m −2 in the water deficit regime and 6.67 plants m −2 (lines) and 7.84 plants m −2 (hybrids) in the normal water treatment. Hybrids of greater plant yield efficiency were less sensitive to water shortage. Among four hybrids yielding the same at normally irrigated dense stand (11.50 Mg ha −1 ), yield loss due to water shortage was 46% for that of the lowest plant yield efficiency (645 g plant −1 ) and 17% for that of the highest plant yield efficiency (880 g plant −1 ). Correlations between hybrid plant yield efficiency and gas exchange water‐use efficiency in dense stand were significant. The low density ensured G × E interaction in the quantitative aspect only and thus was of higher heritability, placing emphasis on parental yield per se. Plant yield efficiency is a key element of hybrid ability to withstand water shortage and cope with environmental heterogeneity.

The present study aimed to investigate whether chlorophyll meter readings (SPAD) can be used as criterion of singleplant selection in maize breeding. Experimentation was performed at the ultra-low density of 0.74 plants/m in order the potential yield per plant to be fully expressed. R-31 honeycomb experiments were conducted in three different areas in Greece (Thessaloniki, Giannitsa and Florina) using 30 inbred lines at well-watered and water-stressed conditions during the 2012 growing season. The chlorophyll meter readings had higher rates at dry conditions, except location of Giannitsa where differences were not significant. Genotypes of highest chlorophyll meter readings were consistent across areas, emphasizing on the character’s stability. A positive correlation between the chlorophyll meter readings and grain yield was strengthening over time and culminated at the physiological maturity stage. There was a clear sign that the chlorophyll meter readings has the potential to be used for the selection of stress-adaptive genotypes and may permit modern maize to be grown at wider range of environments addressing the climate change scenarios. Keywords—Drought-prone environments, honeycomb breeding, SPAD, Zea mays.

This study was undertaken to compare doubled haploid (DH) lines produced from high yielding F3 barley plants selected at two plant densities {i.e., 1.15 plants m-2 (PD1) and 4.61 plants m-2 (PD2)} for two generations (F2 and F3) to the F6 lines produced from the same cross (Niki x Karina) after phenotypic pedigree selection for five generations. These lines were evaluated for three years at farmers' plant density. During the first season (2005-2006) 178 F6 and 17 DH lines were evaluated in rows using adjacent control. The two parents (Niki and Karina) of the F1 barley cross were used as controls. Mid- parent heterosis (MP) (% yield as compared to the mean of the two controls) was estimated, and finally 26 pedigree and 6 DH lines exhibiting 45% and 26% or higher MP heterosis, respectively, were selected. In the next growing season (2006-2007) a randomized complete block design was established to evaluate these lines. From the 32 genotypes studied the 29 were superior to the mean of the two parents in grain yield, whereas 18 of them (i.e. 10 from PD1, 5 from PD2 and 3 DH lines) exhibited 30% or higher MP heterosis. These 18 genotypes were further evaluated during the third growing season (2007-2008). Finally 9 lines (i.e. 4 PD1, 3 PD2, and 2 DH) yielded significantly higher than both of the controls. However, four advanced pedigree lines (2 PD1 and 2PD2) yielded significantly higher than the best DH line. It was concluded that a combination of honeycomb early generation selection for two generations (F2 and F3) and the production of DH lines from high yielding F3 plants could be considered as a beneficial alternative approach only in the case where a comparable number of DH lines are produced and evaluated.

A 2 year field experiment was conducted in northern Greece to study the biomass effects of four oregano (Origanum vulgare) biotypes, used as incorporated green manure, on the emergence and growth of barnyard grass (Echinochloa crus‐galli), bristly foxtail (Setaria verticillata), common purslane (Portulaca oleracea), cotton (Gossypium hirsutum), and corn (Zea mays). The oregano biotypes were selected on the basis of their high phenolic content. The phytotoxic potential of the oregano biotype extracts also was determined in the laboratory by using a perlite‐based bioassay with cotton, corn, and barnyard grass. The bioassays indicated that the germination, root elongation, and fresh weight of cotton, corn, and barnyard grass were reduced by the oregano biotype extracts. In the field, the emergence of common purslane, barnyard grass, and bristly foxtail was reduced by 0–55%, 38–52%, and 43–86%, respectively, in the oregano green manure treatments, as compared with the oregano green manure‐free treatments (the controls). At harvest, the cotton lint and corn grain yields in the oregano green manure treatments were 24–88% and 5–16%, respectively, greater than those in the corresponding green manure‐free, weedy treatments. These results indicated that when the biomass of the oregano biotypes with a high phenolic content were incorporated into the soil as green manure, they could be used to suppress barnyard grass, bristly foxtail, and common purslane in cotton and corn and consequently to minimize herbicide usage.

A field experiment was conducted under semiarid conditions to investigate the effect of cattle manure (20 and 40 t ha -1 ), zeolite (250, 500 and 750 kg ha -1 ), and leonardite (250, 500 and 750 kg ha -1 ) applications on hay yield and nutrient quality of annual ryegrass. Application of manure, leonardite, and zeolite increased ryegrass hay yield by 4, 24 and 47%, respectively compared with the control. In all fertilizer levels, the crude protein (CP) content was greater than the control and increased as the level of each fertilizer was increased. Most fertilizer treatments (except from the first level of cattle manure) gave higher CP yield than the control. All fertilizers increased the content of K, S, Ca, Mg, Fe, Mn and B of ryegrass hay as compared with the control, whereas they had no significant effect on Cu and Zn content. The content of most minerals increased as the amount of manure and leonardite applications increased. In conclusion, all fertilizers (especially zeolite) showed great potential for use in organic agriculture as they can improve plant growth and soil conditions in the long term.