A. S. Lithourgidis

Sustainable production of barley and wheat by intercropping common vetch

Intercropping legumes with cereals for forage production is a sustainable technique showing several environmental benefits. We studied yields, quality and the growth rate of a 2-year experiment including (1) sole crops of common vetch, barley and winter wheat, and (2) intercrops of common vetch with barley and winter wheat using seeding ratios of 55:45 and 65:35. Our results show that the greatest dry matter yields were obtained with wheat and barley sole crops. The lowest yield was obtained with common vetch sole crop. The intercrops produced about 13–30% more dry matter than the common vetch sole crop, but 12–23% less than cereal sole crops. Further, the growth rate of common vetch and cereals was greater when species were grown as sole crops than in intercrops. Quality components indicated an advantage for the sole crop of common vetch followed by its intercrop with barley at the 65:35 seeding ratio, which exhibited higher crude protein yield than the sole crop of cereals and the other intercrops. The results of this study indicate that common vetch intercrops with barley or winter wheat produced higher dry matter than common vetch sole crop. In addition, the intercrop of common vetch with barley (65:35) provided higher forage quality than the other intercrops. Our study highlights that vetch-cereal intercropping can be used as an alternative cropping system which combines sustainability due to N fixation from common vetch, and high yield and forage quality.

COMPETITIVE ABILITY OF WINTER CEREAL–COMMON VETCH INTERCROPS AGAINST STERILE OAT

Intercropping cereals with legumes for forage or food production is extensively used as a cropping practice in many parts of the world. A 2-year field study was conducted using common vetch ( Vicia sativa ), winter wheat ( Triticum aestivum ), triticale (× Triticosecale ), barley ( Hordeum vulgare ) and oat ( Avena sativa ) sole crops as well as common vetch intercrops with each of these cereals in a 35:65 cereal:common vetch ratio based on seed numbers, to determine their ability to compete with sterile oat ( Avena sterilis spp. sterilis ). At nine weeks after planting, fewer sterile oat plants emerged in common vetch sole crop than in cereal sole crops. Intercropping of cereals with common vetch generally did not affect sterile oat stem number and biomass compared with cereal sole crops. At harvest, cereal sole crops provided greater total dry biomass (DB) than the common vetch sole crop. However, triticale and oat produced more DB than winter wheat and barley. In most cases intercropping reduced total DB compared with cereal sole crops. The results of this study indicated that intercropping of the four winter cereals with common vetch did not provide any significant competitive advantage against sterile oat. However, common vetch sole crop showed the greatest suppressive ability against sterile oat among the sole crops or intercrops studied.

Anther Culture Response of Barley Genotypes to Cold Pretreatments and Culture Media

The embryoid formation and plant regeneration in anther cultures of three barley (Hordeum vulgare L.) cultivars (Niki, Karina, Thermi), one F1 hybrid (Niki × Thermi), two F2 populations (Niki × Thermi, Niki × Karina), and two F3 populations (Niki × Thermi, Niki × Karina) were investigated in two solid induction media after cold pretreatment for 14 and 28 days at 4°C . The media used (N6 and FHG) differed in their composition and source of energy (maltose in FHG vs. sucrose in N6). Embryoid frequency and green plant regeneration depended on both the induction medium composition and cold pretreatment. The combination of the FHG induction medium with 28-day-long cold pretreatment was the most efficient in haploid embryoid formation and green plant production. In addition, the green plant production was genotype-dependent. Cv. Thermi and F1 hybrid Niki × Thermi exhibited the highest frequency of green plant production. The parent with high or even moderate frequency of embryoid formation in anther culture could lead to the effective production of green plants from the F1 hybrid or the F2 generation for breeding purposes.

Growth dynamics and agronomic-economic benefits of pea–oat and pea–barley intercrops

Abstract. Pea (Pisum arvense L.) is an important legume in many areas of the world, which is used for forage and grain production and could be used in intercropping systems. Intercropping of pea with oat (Avena sativa L.) and barley (Hordeum vulgare L.), in two seeding ratios 60 : 40 and 80 : 20, was compared with pea and two cereal monocrops for two growing seasons (2008–10), at the Aristotle University of Thessaloniki, Greece. The effect of the intercropping systems was determined on growth rate, plant height, chlorophyll content, DM, and N yield. Also, several competition and economic indices were used to evaluate the intercropping systems, such as land equivalent ratio (LER), relative crowding coefficient (K), aggressivity (A), competitive ratio (CR), actual yield loss (AYL), system productivity index (SPI), monetary advantage index (MAI), and intercropping advantage (IA). Growth rate of pea and cereals was lower by an average of 39 and 64%, respectively, in the intercrops than in the monocrops. DM yield was the highest in barley monocrop (13.00 Mg ha–1) followed by P80O20 intercrop (11.73 Mg ha–1). Pea monocrop, and P80O20 and P80B20 intercrops showed the highest crude protein (CP) concentration (137, 132 and 130 g kg–1 DM, respectively), whereas P80O20 intercrop also produced the highest CP yield (1552 kg ha–1). The LER, K, and AYL values (average 1.09, 1.75 and 0.29, respectively), were greater for both pea-oat intercrops compared with the pea-barley intercrops (average 0.98, 0.92 and 0.06, respectively), indicating that in these systems there was an advantage of intercropping for exploiting the resources of the environment. The A, CR, and partial AYL values in all intercrops were greater for oat and barley than pea, which indicated that cereals were more competitive partners than pea. The highest MAI, IA, and SPI values were recorded for P80O20 followed by P60O40 intercrops indicating that these intercropping systems were the most profitable. The results from this study showed that both pea-oat intercrops were more productive with high CP yield, and also they showed the best land-use efficiency.

Adaptability to organic farming of lentil ( Lens culinaris Medik.) varieties developed from conventional breeding programmes

The development of organic agriculture has raised the demand for crop varieties well-adapted to organic farming systems. Most of the varieties presently cultivated in organic agriculture were developed from conventional breeding programmes. The objective of the present work was to study the adaptability to organic farming systems of lentil ( Lens culinaris Medik.) varieties developed from conventional breeding programmes. Twenty varieties were evaluated over five environments under organic and conventional farming systems from 2005 to 2007. Genotype×system interactions (GSI) for grain yield were significantly different in four out of the five environments and GSI explained 0·03–0·17 of the variance. Spearmans rank correlation index of the 20 varieties between the conventional and organic system ranged from 0·27 to 0·93 in the five environments. Direct selection of the top five varieties in organic systems resulted in significantly higher grain yields than indirect selection in one out of the five environments. However, among the top five varieties, the highest yielding varieties under conventional farming systems were not always the highest yielding varieties under organic farming systems. These results indicate that the demands of organic agriculture for yield performance could be only partially satisfied by varieties developed under conventional breeding programmes.

Conservation tillage: a promising perspective for sustainable agriculture in Greece.

Conservation tillage has been widely implemented in the last decades in several parts of the world as an attractive alternative to conventional tillage due to its potential to protect soils from erosion and compaction, to conserve soil moisture, and to reduce production costs. Significant savings in fuel, labor, and machinery costs are realized with conservation tillage, mainly because fewer trips over the field are required during seedbed preparation. Conservation tillage in Greece has been tested on a limited scale by a minority of farmers on an empirical basis or on an experimental basis by research institutes. Research thus far has shown that, despite some disadvantages in certain cases, conservation tillage can be attractive to farmers because it can provide equal or even greater yields than conventional tillage and also because of its potential for reduced production costs. From this view point, conservation tillage should receive more attention among Greek producers, becoming a viable alternative to conventional tillage and gaining wide acceptance because of its multiple benefits for both the farmer and the environment. Education, technical assistance, and financial assistance to farmers will play a dominant role in this effort.

Estimation of Leaf Area Index and Foliage Area Index of Rice using an Indirect Gravimetric Method

The aim of this study was to present a gravimetric method for the estimation of leaf area index (LAI) and foliage area index (FAI) of rice. The method estimates indirectly the LAI-FAI variation during the growing season using simple measurements during harvest, based on a module of predetermined relations among agronomic parameters. The method confronts the limitations of other methods under specific conditions, such as (a) high plant densities and high LAI-FAI values, where indirect optical methods are restricted and (b) experiments related to crop modeling applications where direct destructive methods are not allowed because they alter the initial design of the experimental setup. The method was applied for the high-yield cultivar (Oryza sativa L. ssp. indica, cv. Thaibonnet) during 2-year evapotranspiration experiments in lysimeters. The method identified the differences between the replicate lysimeters, and LAI-FAI estimations were significantly correlated with the final grain yields and the crop factors obtained from evapotranspiration measurements.

FORAGE YIELD, PROTEIN CONCENTRATION AND INTERSPECIFIC COMPETITION IN RED PEA-CEREAL INTERCROPS

Red pea (Lathyrus cicera L.) is an underutilized protein crop with broad adaptability. Intercrops of red pea with winter cereals have not been studied. A two years field study was conducted with the objective to determine the productivity of intercropping systems of red pea with barley (Hordeum vulgare L.) and triticale (xTriticosecale Wittmack) in two seeding ratios (60:40 and 80:20). Growth rate, dry matter yield, protein content and yield were determined. Several indices were used to evaluate the intercropping systems and analyse competition and interrelationships between mixture components. Growth rate of cereals was lower in the mixtures than in the monocrops. Dry matter yield were the highest in barley monocrop and its intercrop with red pea at 60:40 seeding ratio. Red pea monocrop showed the highest crude protein concentration followed by its intercrops. The land equivalent ratio, relative crowding coefficient (K), actual yield loss (AYL) and system productivity index values were greater for the red pea-barley 60:40 mixture, indicating an advantage of intercropping. The partial K, aggressivity, competitive ratio and partial AYL values indicated red pea as the dominated species in the intercrops. The highest monetary advantage value was recorded for the red pea-barley mixture (60:40). The results indicate that red pea-barley mixture (60:40) was the most productive and produced better forage quality and thus could be adopted by the farmers as alternative option for forage production.

MODELLING YIELDS OF NON-IRRIGATED WINTER WHEAT IN A SEMI-ARID MEDITERRANEAN ENVIRONMENT BASED ON DROUGHT VARIABILITY

SUMMARY Regression models for the prediction of grain yields of non-irrigated winter wheat in a semi-arid Mediterranean environment were developed based on drought variability. Twenty-five years (1980–2004) of climate data and yield data from four soils (sandy loam, clay, clay loam and sandy clay loam soil) in northern Greece were used for this purpose. Two variables were selected as explanatory variables of the models: (a) the monthly precipitation versus the monthly reference evapotranspiration ratio (P/ETo), which describes the monthly drought and consequently the water deficit conditions during the wheat-growing season and (b) the mean observed yield (¯ ) of each soil, which indirectly describes the intrinsic fertility of the soils. A resampling technique using subsets of the data (bootstrapping) was applied to estimate the coefficients of the models, to assess the uncertainty of the selected explanatory variables and to validate the models. The models showed adequate predictive ability of wheat yields, defining the time and intensity of drought effects. The most crucial period for winter wheat was found to be primarily the vegetativereproductive stage period between late winter and mid-spring (i.e. February to April). Soil clay content was found to be the most representative parameter in describing most of the physico-chemical parameters and properties of the soils and consequently the mean yield, indicating that yield is non-linearly correlated with most soil properties. With the proposed models, yield gap (YG) predictions between two growing seasons of the selected soils presented 84% accuracy in all years in the identification of the correct signal (+ or −) of yield increase or decrease, respectively, and adequate performance in the prediction of the mean YG.

Evaluation of lentil varieties and farming system effect on seed damage and yield loss due to bruchid (Bruchus spp.) infestation

Abstract. A major constraint of lentil (Lens culinaris Medik.) cultivation is yield reduction due to field infestation by the seed beetles Bruchus spp. (bruchids). The aim of the study was to assess seed loss (SL) and yield loss (YL) due to bruchid infestation under organic and conventional farming, and to investigate genotypic variability for seed yield of 20 lentil varieties in response to bruchid damage. Field experiments were established over three consecutive years in two areas of central and northern Greece. SL was determined as the percentage of damaged seeds, whereas the weight of the damaged seeds was estimated as YL. Farming system was the main source of variation for both SL and YL. Mean SL under organic farming was 15% and mean YL was 0.13 t ha–1. SL and YL were 2.6- and 8.4-fold higher, respectively, under organic than conventional farming. Valuable genotypic variability was observed with respect to both SL and YL. Early flowering and small seed size were traits associated with low SL and YL. Among varieties, mean SL ranged from 8.5% to 29.2% and YL from 0.06 to 0.31 t ha–1. Evaluation for high yield potential, indicating bruchid tolerance, revealed two types of promising varieties: varieties with high yield and low seed bruchid damage due to phenological escape, and varieties with high yielding potential despite the high SL and YL.