**Influence of Degree Infestation with**  *Echinochloa crus–galli* **Species on Crop Production in Corn**

Teodor Rusu and Ileana Bogdan *University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Romania* 

#### **1. Introduction**

452 Herbicides – Properties, Synthesis and Control of Weeds

Ye, B., Faltin, H., Ben-Hayyim, G., Eshdat, Y. and Gressel, J. (2000). Correlation of

194.

glutathione peroxidase to paraquat/oxidative stress resistance in *Conyza*: determined by direct fluorometric assay. *Pestic. Biochem. Physiol.,* 66: 182–

> Corn continues to be globally one of the main crops, ranking third, after wheat and rice. In Romania it is the main agricultural plant, whose economic importance, especially in the private sector is growing. Given the particularities of this culture, with particular reference to the high sensitivity at infestation with weeds, especially in the early stages of vegetation, corn crop is feasible only if weeds are controlled through various methods. The damage caused by weeds in maize crop are mostly of 30-70% (Sarpe, 1975; Budoi and Penescu, 1996; Oancea, 1998; Bilteanu, 2001; Berca, 2004; Gus et al., 2004; Bogdan et al., 2005; Rusu, 2008) and when the infestation is strong, culture can be fully compromised. The presence in a culture of a small number of weeds is not harmful, but damage caused by weeds grow along with increasing the degree of infestation, depending on the species and age of occurrence of weeds, soil and climate conditions and the moment when weeds are combat (Paunescu, 1996; Bosnic and Swanton, 1997; Perron and Legere, 2000; Bogdan et al., 2001; Fukao et al., 2003; Clay et al., 2005; Rusu et al., 2009). Therefore, specifying the economic threshold of pest is difficult to establish considering the fact that the number of researches in this field until now, is reduced.

> *Echinochloa crus-galli* is one species with a large requirement to water being able to behave as mesophita*,* mesohygrophita*,* hygrophita and hygrohelophita (Anghel et al., 1972; Bogdan et al., 2007). It is especially met on the luvosoils, fertile and wet soils, being wide-spread in all the country but in the north sides it has a lower abundance and general dominance than in the south ones. *Echinochloa crus-galli* is met growing on a large variety of soils and grains, from clay sand or sandy clay soils to medium hard soils. The soils with a relative big capacity of water holding and large fertility insure an ideal sublayer.

> *Echinochloa crus-galli* is a weed with a fascicular, powerful root which is hardly drawn by weeding and it easily sprouts after mowing or while weeding. The seeds get to maturity progressively and they can keep the germinal sufficiency till 8-9 years, germinating by installment. They do not support the flooding (Dimancea, 1967).

> The success of this weed can be imputable to a very low number of seeds generation, easily dispersed from the plant, owning a latent state of the seeds, a fast development and capacity of blooming in a large range of photoperiods (Păunescu, 1997). The number of seeds made

Influence of Degree Infestation

productivity's characters variation.

plant.

with *Echinochloa crus–galli* Species on Crop Production in Corn 455

July and August. The observations were made every 10 days between rising and maturity. We analyzed the rising period according to the sowing date; the leaves appearance, the sprouting and the stem elongation, the panicle appearance and the flourishing beginning, the plants' maturation, the caryopsis' maturation and the dissemination and the

In each lot the plants were rarefied, the observations regarding the productivity elements being done upon a number of 3 plants on surface unit. We chose this density for the reason of the necessary space protection for the *Echinochloa crus-galli* growing in order to touch the maximum values of the productivity parametres according to the biological potential of the

2004: 405.7 mm (excessively wet climate) and 17.6 oC (normal temperatures conditions); 2005: 349.6 mm (excessively wet climate) and 18.05 oC (normal temperatures conditions); 2006: 455.4 mm (excessively wet climate) and 18.5 oC (warm temperatures conditions); 2007: 167.5 mm (excessively dry climate) and 18.8 oC (warm temperatures conditions).

Year Specification The daily average temperature, 0C Rainfall, mm <sup>2004</sup>Value 14.88 562.4

<sup>2005</sup>Value 16.1 505

<sup>2006</sup>Value 16.83 572

<sup>2007</sup>Value 16.98 250.6

The normal values 15.63 358 Table 1. The climate conditions during the 1st of April and the 30th of September in Cluj.

on each lot so that the rising of the plants to be assured for the beginning of May.

medium values of the parameters obtained in the variant of density 3 plants/m².

tillering, panicles length, number of seeds (production).

Deviation - 0.75 + 204.4

Deviation + 0.47 + 147

Deviation + 1.2 + 214

Deviation + 1.35 - 107.4

**2.2 Productivity elements variation of** *Echinochloa crus-galli* **in accordance to density**  In order to follow the variations of productivity parameters to *Echinochloa crus-galli*, the experiences were fixed on the field, in 4 random repetitions, after blocks method, on 1m² lot surface. In the last decade of April there were seeded 200 caryopsis of *Echinochloa crus-galli* 

After the plants rising and the forming of two first leaves, there was done their spacing in order to achieve the density of 50, 20, 10, 5, 3, 2 plants per m². The rating of the plants growing parameters and plants productivity was done in the last decade of July – first decade of August – when the plants were mature enough having as goals: plants height,

The results interpretation was done by means, percents, statistical elaboration (variance analyzes). In order to analyze the values that were obtained there were used control data,

The years of experiment with climatic specific (May 1 – August 31)

by a plant varies between 200 and 10,000. Chirilă (1967) establishes as limits of seeds number/plant from 150 to 10,000. The medium mass of 1,000 bobsleighs is 2.48 g. (Anghel et al., 1972; Berca, 1996). The reserve of *Echinochloa crus-galli* seeds that can be found in the soil can reach impressive values, correlative with the production potential of the species and the vegetative conditions specific to the infestation areas. The number of seeds found by Kott (1953) reported to the surface of one hectare gets to 1-2.5 billion *Echinochloa crus-galli* seeds. Berca (1996) referring to the seeds of this species and their germination, shows that germination happens after one year of seeds forming, by instalment both as structure and life. The germination happens all over the year, especially in the spring time, 1-2 cm depth when the temperature is over 10 ºC. The *Echinochloa crus-galli* seeds have a post maturation period that happens into the soil, especially the upper side of the soil. The length of seminal rest depends by a lot of internal and external factors (Berca, 1996).

The period of germination-rising starts for *Echinochloa crus-galli* in April, depending by the temperature provided by the soil, the minimum germination temperature is 8ºC, and it ends in September. The maximum germination is between May and June, after this period there comes an attenuation of germination proportion and plants rising, so that in October it is accomplished to a very low level.

The elongation of the *Echinochloa crus-galli* plants is in a strong connection with the temperature. In the spring time when the temperature is low the elongation is a slow one but in the summer time when the temperature is high the plants grow very fast (Păunescu, 1997; Rusu et al., 2010). At the beginning the plants grow slowly, after 2-3 weeks after their rising starts the tillering period after that the plants start a very fast growing if the conditions of light, humidity and nutritive substances are assured (Berca, 1996). After the floral branches cutting of this weed, or after the first fructification they sprout again during the same year and fructify for the second time (Staicu, 1969).

*Echinochloa crus-galli* belongs to the yearly monocotiledonate weeds class with late spring germination very harmful for the corn cultures. Growing very fast it asphyxiates the corn crop and infamies the crop.
