Investigation of harvest index influenced by agrotechnical and botanical factors in hairy vetch (Vicia villosa Roth.)

In Hungary, hairy vetch was used as green forage at first, but it later became a green manure plant. Nowadays, it is used as a cover crop and its sowing seed has a good export market. In low fertile soils it is able to produce a big amount of green yield (25–40 t ha) even in spring while its seed yield could be 0.4–0.5 t ha at farm level. In addition to its morphological characteristics hairy vetch is grown mainly with a


INTRODUCTION
In Europe, hairy vetch was first produced in Germany in the middle of the 19 th century (Hanelt, 2001). Its original home is Asia Minor. It is an annual, overwintering species, general all over in Europe from the Mediterranean sea to the Scandinavian peninsula. Its domestic variety came from North-Caucasus to Carpathian basin in the 19 th century (Késmárki, 2005).
In Hungary its cultivation started only in the end of 1800 years mainly for green forage. Nowadays, it is grown as green manure and cover crop (Gondola and Szabóné, 2010). The biggest problem of Hungarian plant growing is the mass production and the simple crop rotation based on cereals. The troubleshooting is hard because of the dramatic decrease in number of animals and homeland consumption. In the past few years there was a decrease in sowing area of protein crops which raises crucial issues concerning crop rotation and land use. Therefore, wide range of alternative plants should be taken under close examination in order to establish biodiversity (Lazányi, 2010.) Among alternative plants hairy vetch is considered to be a first plant of sand soils. (Antal et al., 1966). Brown et al. (1993) found that hairy vetch which is a green manure crop is frequently used as a cover crop. It uses up only small amount of water and fixes nitrogen from the air. Therefore, as a previous crop is able to significantly increase the maize yield both in conventional and in no-tillage systems. Miko et al. (2012) found that biomass yield of green manure plants and their positive effect on soil fertility, under unfavourable ecological conditions, can be increased by adding 50 kg ha -1 nitrogen. Newly incorporation of green manure plants causes inadequate off-spring and slow early developing of after-crop. Therefore, 4-6 weeks should be kept between the incorporation and sowing. (Westsik, 1936;Ballenegger et al., 1936). Kahnt (1986) recommended the green manure application to farms where cereals are prevalent in crop rotation; nitrogen fertilizing is not intended or not possible. The group of green manure plant could be divided into two groups, papilionaceous and all the others. Papilionaceous are applied owing to nitrogen fixing ability of symbionta Rhizobium species while the others are applied due to their other favourable agronomic properties.
According to Dobránszki (2002) green yield of hairy vetch could be 25-45 t ha -1 , while its seed yield could be 500-800 kg ha -1 . Szabóné (2002) pointed out that hairy vetch is able to produce great amount of green yield in low fertile soil even in early spring. Seed yield potentially could be 1.5-2.0 t ha -1 , at farm level it is 0.4-0.5 t ha -1 . As for green yield 25-30 t ha -1 is reachable. Gondola and Szabóné (2010) reported that hairy vetch sowing seed has a good export market. Based on FAO data (Table 1) green yields vary between 4 and 63 t ha -1 , seed yields changes between 0.444 and 1.39 t ha -1 . Lazányi (1994) found that Hungary's ecological conditions give good opportunities to vetch seed production. As excellent green yield was reached with cultivar "Kisvárdai" in Germany, its sowing seed has a good market. This cultivar due to its favourable agronomic properties was registered in Germany under the mane of "Hungvillosa" in 1980.
Harvest index was first calculated to cereals and legumes in India, Western Europe and the USA and proved to be less useful for maize and tuber crops. Harvest index of modern cereal cultivars in high input farming systems is between 0.4 and 0.6, and is an important parameter in plant growing (Donald and Hamblin, 1976) calculated as seed yield divided with total above-ground yield (Donald, 1968).  (Jánossy, 1971). Its plumule elongates strongly and containing no chlorophyll. Later, leaf fundaments became green and emerge above the soil horizon. Pusztai et al (cit. Radics, 2012) says that hairy vetch develops strong root system with long side roots. It is climbing stems reach up to 1.5 m in height. Its stem is rectangular, ramified and procumbent. Its paripinnate compound leaves ending in a ramified tendril, with 6-11 pairs of narrowly elliptical leaflets. Stipules are eglandular. Flowers are middle in size; petals are blueish violet or purple sometimes white in colour. Calyx is short and dented, gibbous at the base. The pods are narrow, flattened and naked being 3-8 seeds in them. Seeds are black 3 mm in diameter, with a matte, long-shaped or ellipsoid hilum. Thousand kernel weight is 18-35 g.
Papilionaceous have favourable preceding crop effect due to nitrogen-fixing Rhizobium species living in root nodules (Vágvölgyi et al., 2018). Due to these bacteria hairy vetch is able to fix a large amount of nitrogen from the air. There are many different evaluations concerning nitrogen fixation, but vetch can fix 150 kg ha -1 nitrogen depending on weather conditions (Gondola and Szabóné, 2010).
Soil tillage should be adjusted to the needs of supporting plant, and should be started with stubblebreaking right after harvesting the preceding crop. (Radics, 2002). Its nutrient need is low. Vetch do not need nitrogen application, has a moderate phosphorus and microelement need but it makes return for higher phosphorus and potassium supply (Erhart, 1996).
According to Gondola and Szabóné (2010) optimal sowing time ranges from mid of September to end of September. Experimental results and farming practices bear clearly out the advantage of growing with supporting plants (wheat, triticale, rye) but for sowing seed purpose it could be grown solely. The suggested seed amount is 40-60 kg ha -1 (1-1.5 million seed) in sole cropping, and 35-40 kg ha -1 (0.8-1.0 million seed) in intercropping. The suggested sowing depth is 4-8 cm.
In soil of good agronomic conditions weeds cannot compete with hairy vetch although hard-to-control weeds need to be managed. Optimal harvesting time is the first part of July, when lower pods are ripen and the seeds could be touchable in them. Seed clearing, drying and de-weevilling is worth to be done at the same time with harvesting (Radics, 2002).

MATERIALS AND METHODS
Our field experiments were carried out in Training Farm of University of Nyíregyháza. The 250 hectare field located in Nyírtelek-Ferenctanya, where ecological farming (lacy phacelia, mustard, sunroot, lupin) is managed in 138 hectares, besides conventional crop growing. In 2018 our experimental site took place in nearly 12 hectare (Figure 1).  Table 2).
The soil is an acid, light (sandy silt texture) brown forest soil with alternating thin layers of clay substances having medium humus content. According to WRB it is called Lamellic Arenosol (Orthodystric) Previous crop was lacy phacelia. Cultivar of hairy vetch was Hungvillosa bred in Kisvárda. The valuable property of the variety is that it gives a large green mass on soils of low fertility early in the spring. It has a good overwintering, bushy and fertile ability. The supporting plant was the Titanium, triticale variety, which can be successfully grown on the fertile acidic sandy soils. Its yielding and tillering ability are excellent. Its height is moderate, its stem is strongly waxy. It is resistant to powdery mildew and yellow leaf foliage. Soil was prepared for sowing in September. Shallow ploughing was followed by seedbed combination. Mixed cropping and strip cropping was applied. In mixed cropping 30 kg hairy vetch seed and 70 kg triticale seed was applied per hectare in the end of September. In order to avoid the seed segregation hopper of sowing-machine was filled with 100 kg mixed seed. Triticale and vetch were sawn in different rows. Ratio of triticale and vetch rows was 6:2 both in strip cropping and in mixed-cropping. Since our experiment was carried out in an ecological farm, no fertilizer or pesticides were applied. Plots were harvested in 1 st July 2019. The 1 m 2 size plots were set up in four repetitions. Plants at early ripen stage were dig out, bound and roots were washed. Dried plant samples were processed in Plant Growing Lab of University of Nyíregyháza. The above-ground biomass yields and grain yields were measured (Figure 2). Statistic evaluation was carried out by SPSS software. The weather conditions of the experimental years are characterized by the precipitation and temperature data (Figures 3-4).
The meteorological data were recorded on the data of the DE AKIT Nyíregyháza Research Institute. The measured values are always compared to the 50-year average. The precipitation from October to April was 225.6 mm that is less than 50-year average and had a negative effect on early developing of hairy vetch greatly impeding rising and spring tillering. Under these circumstances shoot growing slowed down and only lower quantity of green biomass come off. Later, development of the stand speeded up due to the high amount of precipitation fallen in May and June.  At early developing stage of vetch air temperature was at around the 50-year average. In spring (from February to April) low precipitation and sudden up warming caused a remarkable water shortage.

RESULTS AND DISCUSSION
Data needed for counting the Harvest Index are showed in Table 3. In our experiments sole cropping means triticale, strip and mixed-cropping mean triticale plus hairy vetch stands.  Strip cropping reveals the highest above-ground biomass yield and the highest total seed yield. Harvest index of triticale cultivated in sole cropping was higher than that of in strip cropping and in mix-cropping. Differences between sole cropping and strip cropping were not significant. Nevertheless, differences between sole cropping and mixed cropping, and differences between strip cropping and mixed cropping were significant (p-value = 0.037) at p<0.1 level. Biomass yield components are showed in Table 4. The highest root yield was measured in sole cropping followed by strip cropping and mixedcropping. However, the lowest stem yield was observed in sole cropping. Grain yield in sole cropping and in strip cropping reveals almost the same value. Pulse seed yield in strip cropping and mixed-cropping was almost the same. Strip cropping reveals the highest above-ground biomass yield, and apart from root yield it showed higher figures in all the biomass yield components than sole cropping.

CONCLUSIONS
From our results we can conclude that there were no significant differences between the harvest indexes of sole and strip cropping. Harvest index in sole and strip cropping was significantly higher than in mixed cropping. As for above-ground biomass yields and seed yields there were no significant differences between the cropping systems. When data are evaluated it should be taken into account that cropping was carried out under extreme ecological circumstances.