Exploring Winter Lentil and Winter Pea Production in the Northeastern United States

Winter Lentil Seeding Rate Trial

In the first year, the on-farm lentil trial was challenged by poor winter survival as well as annual weed competition, issues that also arose in a neighboring production winter lentil field. On-farm lentil plots were harvested with great effort, but weights were not recorded due to stand inconsistency and weed binding in harvest equipment. The first-year research station lentil seeding rate trial was also heavily infested with chickweed after planting, compromising results by affecting population establishment.

No significant difference in stand count, grain yield, lentil biomass, or weed biomass was detected in the research station trial (Table 2), likely due to extensive weed pressure.

Table 2. Results of one-way analysis of variance by seeding rate in trial of 'Morton' winter lentil sown at five seeding rates. NS indicates no significant difference among varieties.

Trait means in the research trial varied numerically among seeding rate treatments but without explicable trend (Table 3). For example, stand count and lentil biomass were numerically (though not significantly) higher using the lowest seeding rate of 25 lbs/ac, while a much higher seeding rate of 47.5 lbs/ac showed much lower stand count and lentil biomass. It seems that weed pressure overwhelmed the effect of seeding rate treatments, so our approach for 2023-24 focuses on mitigating weed pressure through use of biculture with oat.

Table 3. Trait means by seeding rate in trial of 'Morton' winter lentil sown at five seeding rates.

Winter Lentil Trait Means 2022-23

As a result of collaboration surrounding this project, Martens and researchers decided to use an oat nurse crop (target 60 lbs/ac) interplanted with lentil in 2023-24, in an effort to suppress weeds and aid winter survival by increasing surface residue. Nurse crops have been used successfully by researchers for improving weed suppression and winter survival in hairy vetch, and we hypothesize that this technique holds promise for winter lentil as well. Though not a formal research question of the proposed work, experimentation with a cereal nurse crop for winter lentil is a potentially valuable learning outcome in the case of this novel winter legume crop for our region. If successful, this technique will facilitate better trial data and improved commercial production in future seasons.

Winter Pea Variety Trial
While some deer browsing was apparent in the research station winter pea variety trial, significant differences were found among varieties for all traits except weed biomass (Table 4). For fall vigor, grain yield, pea biomass, and protein, statistical analysis served to identify one or two lower-performing varieties (e.g. Windham for fall vigor, grain yield, and pea biomass and FP6101 for grain yield, pea biomass, and protein) but did not show significant distinction among the top-ranking 7 or 8 varieties. For spring vigor, one variety (KeystoneIcicle) emerged as significantly more vigorous than several others: FP6101, Icicle, Vail, and Windham. 

Table 4. Results of one-way analysis of variance by winter pea variety.

***, **, and * indicate one-way fixed effect ANOVA tests significant at p<0.001, p < 0.01, and p < 0.05, respectively. NS indicates no significant difference among varieties. Significance for grain yield, pea biomass, and weed biomass calculated using square root transformed data. Stand count data not shown due to deer browsing.

A means table sorted by grain yield shows that varieties sorted into three general groups (Table 5). A group comprising Blaze, Vail, and Goldenwood shows numerically higher yield and protein content from shorter, more heavily tillered plants. A second group -- KurtWood, KeystoneIcicle, and Keystone showed moderately high yield from taller, less tillered plants with numerically lower protein content. Finally, a third group composed of Icicle, FP6101, and Windham showed lower yield and biomass with varied plant stature.

Table 5. Trait means by winter pea variety in research station trial, sorted by grain yield.
Winter Pea Trait Means 2022-23

On-farm variety trial plots established well and reflected trends observed in the research station trial (Table 6). As in the replicated trial, Blaze, Goldenwood, and Vail showed the highest grain yield, and Goldenwood yielded less biomass than Blaze or Vail. Similarly, both replicated and on-farm trials showed Keystone and Kurtwood to be intermediate for yield but strong for biomass production. Finally, both trials revealed Icicle and FP6101 as poorer-yielding varieties.

Table 6: Trait values by winter pea variety in on-farm trial, sorted by grain yield.
On-Farm Winter Pea Variety Trial Trait Values 2022-23

Trait correlations from the research station trial suggest trends in the way pea plant architecture and vigor associate with yield traits (Figure 1). Spring vigor shows a modest but significant correlation with both grain yield and pea biomass (r=0.36, p < 0.05 for both traits), but fall vigor is not significantly correlated with either yield trait. This illustrates a known tradeoff between fall vigor and biomass in cold climates. A high, very significant correlation (r=0.87, p < 0.001) between grain yield and biomass suggests that both traits may be selected for concurrently and that similar varieties could suit both grain and forage / cover crop applications.

Our results show high, very significant correlations between stem count and two yield variables: grain yield and pea biomass (r=0.74 and 0.64, p<0.001, respectively). This indicates, unsurprisingly, that varieties with more stems are more productive for both grain and biomass. While plant height is significantly and inversely correlated with stem count (r=-.40, p<0.05), plant height itself is not significantly correlated with grain yield or pea biomass. Thus, stem count – regardless of plant height – is the trait most strongly associated with both grain and biomass yield. However, plant height does show a significant inverse correlation with protein content (r=-0.46, p<0.01), suggesting that short-stature pea varieties may offer higher protein content than longer-vining varieties. 

Figure 1: Trait correlations from 2022-23 winter pea variety trial.
Winter Pea Variety Trial Trait Correlations 2022-23 

This winter pea variety trial was designed to compare multiple grain pea varieties against Keystone, which is the variety most commonly used by grain pea growers in the Northeast. We are interested and gratified that several varieties -- most notably shorter varieties Blaze, Vail, and Goldenwood -- showed numerically higher performance than Keystone for both grain yield and biomass. Finally, grain peas are generally bred for monoculture production, but our trial uses biculture with a small grain, creating an environment of resource competition. We note that varieties with abundant tillers performed well in this environment, and we are curious whether these results will be reflected in the trial's second year.