Perennial Grasses

Classification

According to the type of shoot formation, perennial grasses are classified into:

• rhizomatous, in which the rhizome, i.e., the underground part of the stem, is located underground at a depth of 5-20 cm; new shoots are formed from buds located on the rhizome and at the base of old shoots, for example, smooth brome, creeping wheatgrass, Kentucky bluegrass;
• loose-tufted, in which the tillering node is located at a depth of 1-5 cm; new shoots depart at an acute angle from the mother shoot, forming a loose tuft, for example, timothy, meadow fescue, orchard grass;
• dense-tufted, in which the tillering node is located above the soil surface or at a depth of 1-2 cm; new shoots grow straight upward, closely adjacent to the mother shoot, forming a dense tuft;
• rhizomatous-loose-tufted, which have features characteristic of rhizomatous and loose-tufted grasses, i.e., some shoots have rhizomes, while others form a loose tuft, for example, meadow foxtail, red fescue.

According to stem height and foliage character, Poaceae grasses are divided into:

• tall-growing, i.e., tall with good foliage;
• low-growing, i.e., weakly foliated with shortened shoots in the ground layer;
• semi-tall, occupying an intermediate position between the first two.

Biological features

All species of perennial grasses, except smooth brome, are characterized by the following biological features.

Each developed stem of the plant lives for one year; therefore, when mowing Poaceae grasses for hay, the second cut is formed by vegetative shoots.

Loose-tufted grasses tiller continuously. The most intensive tillering occurs in early spring and autumn. Young shoots formed in the soil during vegetative renewal consume moisture and nutrients through the root system of the mother shoot. Thus, in young shoots, for example of timothy, the synthesizing action of the sucrose enzyme is observed only on the 15th day of life, which means that a shoot formed from a reserve bud feeds at the expense of the mother plant for 2 weeks, and only then does the productive work of the leaves of the new shoot begin.

Each new shoot forms its own root system. All loose-tufted Poaceae grasses have a so-called critical mowing zone, i.e., a height below which mowing leads to the death of the vegetative shoot. The critical mowing zone coincides with the location of the growth point of the vegetative shoot. If the mower blade cuts the growth point completely or partially, the shoot stops further growth and dies. For most perennial grasses, the critical zone is located at a height of 5-6 cm from the soil surface. This biological feature is taken into account when mowing grasses in order to ensure a good second-cut yield.

The maximum increment of the above-ground part for all Poaceae grasses occurs in the period from the beginning of booting to the completion of the heading or panicle emergence phase. This period corresponds to maximum consumption of nutrients and water from the soil.

Grasses are especially responsive to the application of nitrogen fertilizers.

Under optimal conditions, productivity can be maintained for 5-10 years of cultivation in one place. Under dry-land conditions, the life duration, for example for timothy, is 4-5 years; in the lower third of a slope or on lowland meadows, it is 8-10 years. For this reason, loose-tufted grasses in seed-growing farms specializing in grass seed production are included in crop rotations in which perennial grasses account for up to 80% of the rotation area. Thus, for the Non-Chernozem zone, the following crop rotation schemes are recommended:

• 1 — Poaceae grasses (cover-crop-free sowing); 2-4 — Poaceae grasses for seed; 5-6 — row fodder crops and potatoes; 7 — Poaceae grasses with undersowing of clover; 9 — clover for seed;
• 1 — Poaceae grasses (cover-crop-free sowing); 2-4 — grasses for seed; 5-6 — row crops (potatoes, fodder root crops, maize).

Perennial Poaceae grasses form a powerful root system. The ratio of the mass of underground organs to the mass of above-ground organs in the flowering phase is 0.81 for meadow fescue, 0.82 for orchard grass, and 1.08 for smooth brome (VNII of Forages). This biological feature promotes the accumulation of organic matter in the soil when cultivating perennial Poaceae grasses.

Main crops

Perennial grasses include:

• smooth brome (Bromus inermis);
• wheatgrass (Agropyron sp.);
• meadow fescue (Festuca pratensis);
• timothy (Phleum pratense);
• orchard grass (Dactylis glomerata);
• ryegrass (tall (Arrhenatherum elatius), multi-cut (Lolium multiflorum), pasture (Lolium perenne)).
• slender wheatgrass (Elymus trachycaulus);
• Siberian wildrye (Elymus sibiricus);
• meadow foxtail (Alopecurus pratensis).

Importance

Perennial grasses are grown in mixed sowings with leguminous grasses. Joint sowings of Poaceae and leguminous grasses make it possible to level out yields by year, increase the duration of use of grass stands, and balance the nutritional qualities of grass mixtures.

100 kg of dry matter of perennial grasses harvested in the heading (panicle emergence) phase contain 70 feed units and 8 kg of protein; in the flowering phase, 45 feed units (VNII of Forages named after V. R. Williams).

Protection of seed crops from diseases, pests and weeds

In sowings of perennial grasses intended for seed, to control helminthosporiosis, the crops are sprayed with Tilt, Atlant, Titan, Titul 250, Titul 390.

To control the ear fly, spraying is carried out in the phase of hidden formation of the spike with Diazolin.

To control annual dicotyledonous weeds, the crops are sprayed with 2,4-D, Dezormon, Aminopelik, Octapon Extra, Agritox.

References

1. Vavilov P. P., Gritsenko V. V., Kuznetsov V. S. et al. (1986). Crop Production. Edited by Vavilov P. P. 5th ed., revised and enlarged. Moscow: Agropromizdat.
2. Kolomeichenko V. V. (2007). Crop Production/Textbook. Moscow: Agrobiznescenter.
3. Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Farming and Crop Production. Moscow: Bylina.