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© 2006 Plant Management Network.
Accepted for publication 7 April 2006. Published 21 June 2006.

Seeding Date, Plant Density, and Cultivar Effects on Chickpea Yield and Seed Size in Eastern Oregon

Stephen Machado, Assistant Professor, Crop and Soils, Columbia Basin Agricultural Research Center, P.O. Box 370, Oregon State University, Pendleton 97801; Christopher Humphreys, Columbia Basin Agricultural Research Center, P.O. Box 370, Oregon State University, Pendleton 97801; Brian Tuck, Professor, Crop and Soils, Wasco County, 400 E. Scenic Drive, Suite 2.278, Oregon State University, The Dalles 97058; and Mary Corp, Associate Professor, Crop and Soils, Umatilla County, Umatilla Hall, P.O. Box 100, Oregon State University, Pendleton 97801

Corresponding author: S. Machado. stephen.machado@oregonstate.edu

Machado, S., Humphreys, C., Tuck, B., and Corp, M. 2006. Seeding date, plant density, and cultivar effects on chickpea yield and seed size in eastern Oregon. Online. Crop Management doi:10.1094/CM-2006-0621-01-RS.

Abstract

The effects of seeding chickpea (Cicer arietinum L.) cultivars Dwelley and Sinaloa at different dates, row spacing, and rates were evaluated at the Columbia Basin Agricultural Research Center (CBARC) near Pendleton, OR. Highest seed yields and largest seeds were produced when both cultivars were seeded in early April. Delaying seeding until late April resulted in yield reductions of up to 6 lb/acre/day. Sinaloa produced significantly higher yields and larger seed than Dwelley at all the seeding dates. The optimum seeding rate for Sinaloa and Dwelley was 4.7 plants/ft² and 3.4 plants/ft², respectively. Dwelley produced higher yields in wider (12-inch) than in narrower (6-inch) rows and Sinaloa produced higher yields in narrower than wider rows. At the lowest plant population (2.1 plants/ft²), row spacing did not affect yields at all seeding dates. When seeded in early April, high chickpea yields were obtained when seeded in narrow rows at 3.4 plants/ft² or in wider rows at 4.7 plants/ft². Higher seeding rates increased yields in late seeded chickpeas when moisture was not limiting.

Introduction

Chickpea (Cicer arietinum L.) is a cool-season annual pulse crop that is grown in tropical, subtropical, and temperate regions of the world (1,3,6). Small, angular, and colored seeds are known as desi types and large, ram-head shaped and beige-colored seed are known as kabuli types (4,6). The desi types predominate in the Indian subcontinent. Kabuli types dominate American production because of their high value for use as an ingredient in salad bars. However, there is a potential for desi export markets if production is expanded (2).

Chickpea is a relatively new commercial legume crop to eastern Oregon. Information on cultivars, seeding dates, plant density, fertility, and inoculation is lacking for this region. Eastern Oregon has a Mediterranean-type climate that is characterized by wet winters and dry summers. Thus, chickpeas, seeded in the spring, mature when water supply and residual moisture are decreasing. If soil temperature and field conditions are suitable, early spring seeding should ensure adequate moisture for optimum plant growth and yield. If seeding is delayed by wet soil conditions, it is likely that the results will be shorter plants, late-formed flowers and pods, and reduced seed yield (5). It is well documented that flower and pod abortion increase if flowering and pod set coincide with hot, dry weather (1,5). It is not clear whether late-seeded chickpea should be seeded at higher seeding rates to compensate for pod abortion. High plant populations under limited soil moisture conditions may induce water stress if canopy development increases accordingly. Increasing row spacing may alleviate water stress caused by high plant populations by delaying complete canopy cover and maximum daily water use during stressful periods. The effects of management decisions on seed yield and size are not known. Therefore, the objective of this study was to determine optimum seeding dates and plant density for commercially available chickpea cultivars in eastern Oregon.

Field Procedures

This experiment was conducted at the Columbia Basin Agricultural Research Center (CBARC), Pendleton located at 45.7°N, 118.6°W, with elevation of 1439 ft. The soil is a coarse, silty, mixed, mesic Typic Haploxeroll (Walla Walla silt loam). The average annual crop-year (September 1 to August 31) precipitation is about 16 inches. To determine the optimum seeding date and plant density of chickpeas, two kabuli cultivars, 'Dwelley' (Ascochyta blight resistant), and 'Sinaloa' (Ascochyta blight susceptible), were sown in early, mid, and late April in 2002 and 2003. Both 'Dwelley' and 'Sinaloa' have upright plant architecture but differ in leaf type with 'Dwelley' producing unifoliate-type leaves and 'Sinaloa' producing fern-type leaves. The chickpeas were sown in two spacing treatments (6- and 12-inch) at a target seeding rate of 1.5, 3, and 4.5 seeds/ft² (equivalent to 75, 160, and 240 lb/acre, respectively for Dwelley and 81, 162, and 243 lb/acre, respectively for Sinaloa). Seeding rates were adjusted (based on germination tests) to ensure that target populations were achieved. The experimental design was a split-split-split plot arrangement in a randomized block design (4 replications) with year as a whole plot factor, seeding dates as sub plots, row spacing as sub-sub-plots and cultivar and seeding rate factorial as sub-sub-sub-plots.

Chickpeas were planted following winter wheat each year and seeding was done with a Hege plot seeder (Hege USA, Colwich, KS) in sub-sub-sub plots that were 5 ft × 20 ft. Plant population, days to flowering, days to maturity, pod and seed fill duration, seed yield, and seed size were recorded for each plot. Plant population was determined 14 days after emergence by counting the number of seedlings in two, 3-ft row lengths in each plot. Date of flowering was recorded when the first flowers opened in 50% of the plants. Date of maturity was recorded when pods dried in 50% of the plants. Podding and seed filling duration was described as the period when first pods were observed to maturity. A Hege plot combine (Hege USA, Colwich, KS) was used to harvest plots to obtain seed yield. Seeds were cleaned and graded for size using a sieve technique. Seeds that did not pass though a 22/64 sieve were classified as "A" grade and those that passed a 22/64 sieve but not through a 18/64 sieve were classified as "B" grade. Data on plant growth, seed yield and seed size, were analyzed by PROC GLM procedures in SAS (SAS Institute Inc., Cary, NC).

Growth and Development

The number of plants/ft² in the low, medium, and high population treatments was 2.1, 3.4, and 4.7, which were 0.6, 0.4, and 0.2 plants/ft² above the target plant population of 1.5, 3.0, and 4.5 plants/ft², respectively. Both cultivars took 57 to 59 days to flowering when seeded in early or mid April. When seeded in late April, the chickpeas took only 50 days to flower. Chickpeas seeded in early, mid, and late April reached maturity in 113, 104, and 94 days, respectively. Podding and seed filling duration was 56 days for chickpeas seeded in early April and about 44 days for chickpeas seeded in mid and late April. Late seeded chickpeas emerged and grew under increasing temperatures and higher evaporative demand (Fig. 1) resulting in short vegetative and reproductive phases.

Fig. 1. Precipitation, temperature, and evapotranspiration distributions at CBARC, Pendleton in 2001-2002 and 2002-2003 crop-years.

Seed Yield and Seed Size

There were interactions between year, seeding date, and cultivar; year, row spacing, and cultivar; year and seeding rates; cultivar and seeding rates; and seeding date, row spacing and seeding rates on chickpea seed yield (Table 1). Seed size was influenced by interactions between year, seeding date, and cultivar; seeding date, row spacing, and cultivar; and seeding date, row spacing, and seeding rates (ANOVA not shown).

Table 1. Anova table: Seeding date, plant density, and cultivar effects
on seed yield of Chickpeas in 2002 and 2003 at CBARC, Pendleton, OR.

Year, seeding date, and cultivar effects. The effects of year, seeding date, and cultivar on seed yield are shown in Table 2. On average, seed yield was highest when the two chickpea cultivars were seeded in early April. Delaying seeding to mid April and late April reduced yield by 99 and 190 lb/acre, respectively. This is equivalent to a yield reduction of about 3.6 and 6.3 lb/acre/day, respectively. Reduction in seed yield could be attributed to increasingly hot and dry conditions experienced by late seeded chickpeas. In 2002, chickpeas seeded in early April were attacked by Fusarium solani, F. oxysporum, and bean leafroll and alfalfa mosaic viruses. Since the highest yields were produced by chickpeas seeded in early April, yield losses due to disease incidences could not be estimated.

Table 2. Year, seeding date, and cultivar effects on chickpea yield and seed size (2002 and 2003) at CBARC, Pendleton, OR.

 ^x Means with same letters within a column are not significantly different at the 5% level of probability. The letters do not compare means in rows.

In both years, Sinaloa produced higher yields than Dwelley at all seeding dates. On average, Sinaloa produced 150, 58, and 205 lb/acre more seed than Dwelley when seeded in early, mid, and late April, respectively. Dwelley yields were reduced when seeded in late April of 2002, and in mid and late April of 2003. In contrast, there were no significant differences in yield when Sinoloa was seeded either in mid or late April. The reduction in yield with delay in seeding was more drastic in Dwelley than in Sinaloa in 2002, a drier year than 2003. This may indicate that Sinaloa was better adapted to drier conditions than Dwelley.

Seeds were larger in 2003, a wetter year, than in 2002, a drier year. Seed size followed trends in yield and decreased as seeding was delayed (Table 2). The decrease in seed size with delay in seeding was more drastic in Dwelley than in Sinaloa. Sinaloa had significantly larger seeds than Dwelley. Large seeds were significantly correlated with seed yield in 2002 (r = 0.75, P < 0.01) and in 2003 (r = 0.42, P < 0.01).

Year, row spacing, and cultivar effects. In 2002, there were no significant differences in seed yield for both cultivars when seeded in 6- or 12-inch rows (Table 3). In 2003, Dwelley produced higher yields in the wider rows. The opposite was true for Sinaloa. The reasons for the differences were not clear but this was probably attributed to leaf structure. Sinaloa has a fern-type leaf structure that may allow light penetration into the canopy making this cultivar less sensitive to crowded conditions in narrow rows. Row spacing had no effect on seed size in both years in both cultivars (Table 3).

Table 3. Year, row spacing and cultivar effects on chickpea yield and seed size in 2002 and 2003 at CBARC, Pendleton, OR.

 ^x Means with same letters within a column are not significantly different at the 5% level of probability. The letters do not compare means in rows.

Year and plant population (seeding rate) effects. Seed yield increased with increasing plant population in both years (Table 4). However, there were no further significant increases in yield when plant populations increased above 3.4 plants/ft² in 2002 probably because it was a dry year. In 2003, a wetter year, the highest yields were produced at the highest plant population of 4.7 plants/ft². Increasing plant population did not affect seed size in either year (Table 4).

Table 4. Year and plant population effects on chickpea yield and seed size in 2002 and 2003 at CBARC, Pendleton, OR.

 ^x Means with same letters within a column are not significantly different at the 5% level of probability. The letters do not compare means in rows.

Cultivar and plant population (seeding rate) effects. Increasing plant population increased seed yield of both cultivars (Table 5). However, there were no further significant increases in yield of Dwelley when plant population increased above 3.4 plants/ft². For Sinaloa, the highest seed yield was produced at the highest plant population of 4.7 plants/ft². Seeding rates did not influence seed size in either cultivar (Table 5).

Table 5. Cultivar and plant population effects on chickpea yield and seed size in 2002 and 2003 at CBARC, Pendleton, OR.

 ^x Means with same letters within a column are not significantly different at the 5% level of probability. The letters do not compare means in rows.

Seeding date, row spacing, and plant population (seeding rate) effects. Chickpea yields generally decreased as seeding was delayed from early to late April at all seeding rates and row spacings (Table 6). At each seeding date, chickpea yields increased as seeding rates increased in both narrow and wide rows. The increase in yield was higher in early than late seeded chickpeas. When seeded in early April, row spacing did not influence chickpea yield at a low plant population (2.1 plants/ft²). At this seeding date, increasing row spacing decreased chickpea yield when plant population was 3.4 plant/ft² and increased chickpea yields when plant population was 4.7 plant/ft². When chickpea was seeded in mid or late April, row spacing had no effect on yield, suggesting that as yield potential declines, management has less influence on yield outcomes.

Table 6. Seeding date, row spacing, and plant population effects on chickpea seed yield and seed size in 2002 and 2003 at CBARC, Pendleton, OR.

 ^x Means with same letters are not significantly different at the 5% level of probability. Letters in the same line with means compare means between row spacings at each seeding date. Letters in boldface and below means compare means between plant populations within a row spacing.

Delaying seeding from early to late April decreased seed size (Table 6). When chickpeas were seeded in early or late April, increasing plant population did not affect seed size in both narrow and wide rows. Furthermore, there were no significant differences in seed size between the narrow and wide rows at each plant populations. When chickpeas were seeded in mid May, seed was larger in wide rows when plant population was 2.1 plants/ft² and smaller in wide rows when plant population was 4.7 plants/ft². At 3.4 plants/ft², there were no differences in seed size between wide and narrow rows.

Conclusions

Results indicated that highest chickpea yields were produced when chickpeas were seeded in early April. Given that crops in the Pacific Northwest rely mainly on residual moisture from winter precipitation, it is highly likely that higher yields could be expected in chickpeas seeded earlier than April as long as soil temperatures are not too low for germination, field conditions permit seeding, and diseases incidences are low. Seeding earlier than April should be investigated.

Both cultivars performed best when seeded early. Sinaloa was, however, better yielding than Dwelley when seeded late in April. Sinaloa seeds were larger than seeds of Dwelley at all seeding dates. Larger seeds fetch higher prices on the market. Based on yield and seed size, Sinaloa is best suited for eastern Oregon. In areas where Ascochyta blight is prevalent, it would be recommended to seed Dwelley that is resistant to this disease. Increasing seeding rates increased yields. The optimum seeding rate for Dwelley and Sinaloa was about 3.0 and 5.0 seeds/ft², respectively. However, higher seeding rates may not be economical. The decision to use high or low seeding rates will depend on seeding date and row spacing. At low seeding rates, narrow or wide rows did not affect yields at all seeding dates. If seeded in early April, chickpeas produced high yields when seeded in 6-inch rows at 3.4 seeds/ft² or in 12-inch rows at 4.7 seed/ft². In late seeded chickpeas, row spacing appears to have no effect on yield at both seeding rates. However, when seeded later than the first week of April, higher seeding rates increased yields when moisture was not limiting.

Acknowledgments

Contribution of Oregon State University, Columbia Basin Agricultural Research Center, PO Box 370, Pendleton, OR 97801.

The authors would like to thank Karl Rhinhart and Erling Jacobsen for their help in this experiment. This research was supported by the Oregon Department of Agriculture and STEEP.

Literature Cited

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