Management of Field Pea Under Irrigation

Introduction

Field pea acreage in Saskatchewan increased from 130,000 acres in 1990 to 1,150,000 acres in 1994. Acreage of pea under irrigation has also increased as producers take advantage of good yield potential and reasonable markets. Field pea offers a number of advantages in the crop rotation such as reduced nitrogen costs, spreading of the work load (especially at harvest), and as an option in extending cereal rotations.

Research on irrigated pea production was started at the Saskatchewan Irrigation Development Centre in 1987 as part of the specialty crops development program. The objectives are to identify suitable varieties, and to develop appropriate management practices. The results of trials conducted through to the 1991 season are summarized.

Results of the Trials

• Short semi-leafless pea varieties perform best under irrigation.
• Early Seeding produced high yields and larger seeds.
• A seeding rate equivalent to 55 seeds/m² (45 seeds/sq. yd.) is adequate for high yields.
• Peas require 300 to 350 mm ( 12 to 14 inches) of water as rain plus irrigation during the growing season.

Variety Evaluation

Short semi-leafless varieties perform well under irrigation. These types are less likely to lodge, helping to control yield loss due to disease (such as Sclerotinia stem rot), and due to poor seed fill. For more information refer to the CSIDC publication Crop Varieties for Irrigation.

Date of Seeding

Pea seedlings can tolerate frost to about -5°C. Seedlings that do suffer frost damage can regrow from underground buds. Therefore, peas can be sown early in the spring. Early seeding takes full advantage of cooler temperatures in spring and early summer. Another advantage to early seeding is an earlier harvest, especially with green peas which are susceptible to bleaching.

Seeding date studies were conducted by the CSIDC in 1989 and 1990 on large-scale, on-farm plots using commercial equipment. Early seeding produced higher yields and larger seeds compared to late seeding (Table 1).

Seeding Rate Studies

The recommended seeding rate for pea, based on dryland studies is 80 seeds/m2. Seeding rates of 55, 80 and 110 seeds/m2 were tested in 1989 and 1990 using Radley pea. There were no significant yield differences observed between seeding rates (Table 2). For irrigated pea production, the seeding rate can be reduced by about 30% from the current recommendation if weed control is adequate.

NS = no significant difference

Seeding Depth

A two year study with Radley pea sown at three depths (Table 3) showed that seeding depth did not affect plant stand or seed yield. Adequate soil moisture provided by irrigation allowed normal germination and emergence at all depths.

* Average of 3 years
NS = no significant differences within years

Irrigation Scheduling

Pea is sensitive to moisture stress at flowering. A good soil reserve is essential immediately prior to and during flowering, particularly for short varieties with a determinate growth habit.

An experiment was conducted to compare the effect of irrigation of pea varieties with different growth habits and different leaf types. Radley (semi-leafless, short), Tipu (semi-leafless, tall), Express (tare-leaf, short), and Century (standard, tall) peas were included in the test. The study was conducted under the linear irrigation system where individual plots can be watered precisely as required. Pea yields increased as water use rose to 300 to 350 mm (12 to 14 inches) as rain plus irrigation.

The tall and short types both responded similarly to different irrigation levels in the absence of disease. In a year of a high incidence of Sclerotinia stem rot, such as 1990, considerable yield loss in tall varieties were observed with increased irrigation.

Fungicides for Foliar Disease

Conditions were favorable for disease during 1990. Foliar fungicide application was effective in controlling disease and resulted in a yield increase (Table 4). There was no benefit to using a fungicide on pea in 1991, a year of low disease incidence.