1. Title: Identification of High Yielding, Root Rot Tolerant Sweet Corn Hybrids

Transcription

1 Report to the Oregon Processed Vegetable Commission Title: Identification of High Yielding, Root Rot Tolerant Sweet Corn Hybrids 2. Project Leaders: James R. Myers, Horticulture 3. Cooperators: Brian Yorgey, Food Science and Technology Cindy Ocamb, Botany and Plant Pathology 4. Project Status: Terminating 30 June, Project Funding: $21,721 total Funds were used for a major portion of the support of a vegetable technician, student labor, supplies, processing plant evaluation of moisture content, and research farm expenses. 6. Objective: Identify sweet corn hybrids released for the processing market for high and stable yields under heavy and light root rot pressure. 7. Report of Progress: Three trials were planted at two locations on 27 June to evaluate sweet corn hybrids for performance under root rot conditions. Two locations (Vegetable Research Farm and Botany Farm) with high root rot incidence were used. Both have had continuous corn for at least the past five years. The fields have slightly different histories in that the Vegetable Farm fields have had no additional inoculum added, whereas the Botany Farm field has had direct Fusarium inoculation and roots from infected fields added. Sugary/sugary enhanced and supersweet hybrids were grown in isolation from one another on the Vegetable Farm to allow the collection of ear quality data. At the Botany Farm, supersweet and sugary types were grown together, and only yield was evaluated. The Vegetable Farm trials consisted of four replicates with two row plots 30 feet in length, while only one row per plot was established at the Botany Farm. At the Vegetable Farm, one row of each plot was used to determine yield and for processing evaluation, while the other row was used for root rot evaluation and determining kernel moisture. Hybrids were planted with a belt planter then thinned to normal stand (nine inch spacing on 30 in. rows). Data collected included root rot on the primary, mesocotyl and adventitious roots, browning of the nodes, crown rot at harvest maturity, silking date, kernel moisture, and ear number and weight (including both cull and net weight). Kernel moisture was determined at the OSU Pilot Plant. Raw product evaluation was conducted on those hybrids for which seed company funding was obtained (this included all hybrids this year). Hybrids evaluated in trials are show in table 1. Five were supersweet and ten were sugary types. Performance over the locations was fairly uniform, with no variety by environment interaction, and entries showed similar ranking for yield and root rot parameters across trials. Average net yields were 6.9, 7.0, and 6.5, respectively for the Vegetable Farm supersweet, sugary, and Botany Farm combined trials. Several sugary hybrids (GH 6377, GH 4927, GH 6462, GH 8267, and GH 2171) equaled or exceeded Coho (tolerant check) for yield at both locations (Tables 2 & 3, Figure 1), with GH 6377 also having excellent ear quality and flavor (Table 5). The other

2 three hybrids in the sugary trial (Evita, GH 6487, and Tamarack) all seemed to be adversely affected by root rot, with yields similar to or worse than Jubilee (susceptible check). Again this year, GSS 1477 had the highest yield among supersweet types (Tables 2 & 4, Figure 1), but with ear and kernel variability this year that affected ear quality (Table 6). Of the other supersweet types, all three (Magnum II, Marvel, and CSH YP3-99) had yields higher than Supersweet Jubilee Plus in the Vegetable Farm plots (Table 4, Figure 1) but only Magnum II had statistically higher yields at the Botany Farm (Table 2, Figure 1). Root rot pressure was extremely severe at all three locations with an overall primary root rot of 99.3% (Table 7). Mean by trial for primary root rot was 99% at the Botany Farm (Table 8), 100% in the sugary Vegetable Farm trial (Table 9), and 100% in the supersweet trial at the Vegetable Farm (Table 10). Only Coho (tolerant check) showed statistically lower % infection at 87.5% at the Botany Farm location (Table 8). GSS 1477 did not differ significantly from Coho at the Botany Farm in the overall analysis for primary root infection, but all other varieties did. For all parameters, the check cultivars Coho (tolerant) and Jubilee (susceptible) showed relative ranking as expected. In the overall evaluation, one hybrid (Evita) had significantly less adventitious root rot compared to Coho, and two (GH 6462, Evita) were significantly better than Jubilee (Table 7, Figure 2). No hybrids had significantly less adventitious root rot than Coho when Botany Farm was analyzed alone, but 3 hybrids (GH 6377, GH 6462, and Evita) were better than Jubilee in this trial (Table 8). In the Vegetable Farm sugary trial, Evita, was significantly lower in adventitious root rot compared to Coho, and none were significantly worse (Table 9). Differences were not significant for any of the root rot parameters in the Vegetable Farm supersweet trial (Table 10). Root worm damage was higher this year than last, with higher readings at both locations. When root rot and yield parameters were subjected to correlation analysis, several moderate to strong significant associations were observed in the analysis of the overall data set (Table 11). Primary, mesocotyl and adventitious root rot, and crown rot, were all strongly correlated. Brown node was correlated with adventitious and primary root rot and crown rot, but not significantly correlated with mesocotyl root rot. The correlation between root worm damage and other root rot parameters was inconsistent. There was no significant correlation between yield (net ) and primary, mesocotyl or adventitious root rot this year, but brown node, crown rot and root worm damage were all negatively correlated with yield. Ear diameter and kernel depth also correlated negatively with brown node and crown rot, but not with root worm damage. Ear length was not correlated with any trait except net, where it showed a weak negative correlation. We would have expected ear length to be positively correlated with yield. When trials were analyzed separately correlations were weaker, but general tendencies held. In general, the lack of correlation of primary, mesocotyl and adventitious root rot with yield parameters may be the result of such high incidence, with little variation among hybrids for root characters. Reduction in yield from brown node and crown rot appears to be due mostly to reduced kernel depth. 8. Conclusions: A number of hybrids appear to have better performance under root rot conditions than Jubilee and Supersweet Jubilee. Several sugary hybrids appear to have potential as root rot tolerant replacements for Jubilee. Of these, GH 6377 had the best overall yield performance and very good ear quality.

3 Table 1. Sweet corn entries grown in trials on root rot infested ground at the Oregon State University Botany and Vegetable Research Farms, Corvallis, Company Type Color GH 2171 Syngenta su yellow GH 4927 Syngenta su yellow GH 6377 Syngenta su yellow GH 6462 Syngenta su yellow GH 6487 Syngenta su yellow GH 8267 Syngenta su yellow Jubilee Syngenta su yellow Tamarack Crookham su yellow Evita Crookham su yellow Coho Harris Moran su yellow GSS 1477 Syngenta sh2 yellow Magnum II Syngenta sh2 yellow Supersweet Jubilee Plus Syngenta sh2 yellow CSH YP3-99 Crookham sh2 yellow Marvel Crookham sh2 yellow

4 Table 2. Yield and ear measurements for selected sweet corn hybrids grown in a root rot trial on the OSU botany research farm, Corvallis, z Days to Harvest Plants /Plot Gross Net Ears /Plot Ears /Plant Lb/Ear Net Culls GH Coho GSS GH GH GH GH Magnum II Evita GH Tamarack Marvel Supersweet Jubilee Plus CSH YP Jubilee LSD 0.05 y NS z Planted June 27 in rows 30" apart, thinned to 9" between plants. Harvested plot length was 20'. Gross is the weight of all harvested unhusked ears. All values shown are means of 4 replications arranged in randomized complete blocks. All data except cull were obtained from typical husked good ears. y NS = Non-significant.

5 Table 3. Yield and ear measurements for selected sugary sweet corn hybrids grown in a root rot trial on the OSU vegetable research farm, Corvallis, z Days to Harvest % Moisture Plants/Plot Gross Net Ears /Plot Ears /Plant Lb/Ear Net Culls Ear Length (in.) Ear Dia. (in.) Kernel Depth (mm) GH GH GH GH Coho GH Evita Jubilee GH Tamarack LSD Tenderness z Planted June 27 in rows 30" apart, thinned to 9" between plants. Harvested plot length was 20'. Gross is the weight of all harvested unhusked ears. All values shown are means of 4 replications arranged in randomized complete blocks. All data except cull were obtained from typical husked good ears. For ear length and ear diameter, the value used for each replication was the average of 10 individual primary ear measurements. Tenderness value is the average of 10 individual primary ear measurements per replication, determined by a spring-operated puncture gauge; lower numbers indicate more tender pericarp.

6 Table 4. Yield and ear measurements for selected supersweet corn hybrids grown in a root rot trial on the OSU vegetable research farm, Corvallis, z Days to Harvest % Moisture Plants/Plot Gross Net Ears /Plot Ears /Plant Lb/Ear Net Culls Ear Length (in.) Ear Dia. (in.) Kernel Depth (mm) GSS Magnum II CSH YP Marvel Supersweet Jubilee Plus LSD 0.05 y NS NS Tenderness z Planted June 27 in rows 30" apart, thinned to 9" between plants. Harvested plot length was 20'. Gross is the weight of all harvested unhusked ears. All values shown are means of 4 replications arranged in randomized complete blocks. All data except cull were obtained from typical husked good ears. For ear length and ear diameter, the value used for each replication was the average of 10 individual primary ear measurements. Tenderness value is the average of 10 individual primary ear measurements per replication, determined by a spring-operated puncture gauge; lower numbers indicate more tender pericarp. y NS = non-significant.

7 Table 5. Ear quality evaluations for selected sugary sweet corn hybrids grown in a root rot trial on the OSU vegetable research farm, Corvallis, z Days to Harvest Shape Row Straightness Uniformity Tip Fill Ear Maturity Kernel Flavor GH Good yield GH Some culls have very large kernels; some half-filled ears GH Some curved ears; not sweet; uneven kernels Refinement Overall Score GH Coho GH Evita Jubilee GH Tamarack z Planted June 27. Scores based on a 1-5 scale, with 5 = best. Row No. Notes Small ears; very good flavor; good yield with many second ears Deep kernels; good flavor Good corn flavor but little sweetness Variable for maturity; poor tip fill Highly variable and yield is down; probably due to root rot infection Uniform; excellent quality; low yield may be due to root rot infection Small yellowing plants appear to be root rot infected; oval cobs; tapered shape

8 Table 6. Ear quality evaluations for selected supersweet corn hybrids grown in a root rot trial on the OSU vegetable research farm, Corvallis, z Uniformity Shape Row Straightness Tip Fill Ear Days to Harvest Refinement Maturity Kernel Flavor Overall Score Row No. Notes GSS Magnum II CSH YP Good yield; very sweet but not much corn flavor; best ears are nice but coarse and much variability; tough Highly variable; very large kernels; poor tip fill Pale color; mild flavor with "green" after taste Marvel Highly variable; curved ears Supersweet Jubilee Plus Somewhat variable--probably due to root rot infection z Planted June 27. Scores based on a 1-5 scale with 5 = best.

9 Table 7. Overall root disease ratings of sweet corn hybrids grown at the OSU Botany and Vegetable Research Farms, Corvallis, 2007 z Primary root rot (%) Mesocotyl root rot (%) Adventitious root rot (%) Brown Root node y Crown rot x worm w Evita GH Coho CSH YP Magnum II GH GH GSS GH SS Jubilee Plus Jubilee GH Marvel Tamarack GH LSD z Trials planted June 27. Plants dug and rated October 11. Combined data from 2 trials per entry, 4 reps per trial, 3 plants per rep. y Number of nodes above the soil line with brown discoloration. x Scale of with 0=no crown discoloration, 0.5=beginning of discoloration, 1=crown rot present with black discoloration. w Scale of 1-3 with 1=no evidence of feeding, 2=less than 75% adventitious roots with feeding, 3=more than 75% roots with feeding.

10 Table 8. Root disease ratings of sweet corn hybrids grown at the OSU Botany Farm, Corvallis, 2007 z. Primary root rot (%) Mesocotyl root rot (%) Adventitious root rot (%) Brown Root node y Crown rot x worm w Evita GH Coho GH CSHYP GH GSS Magnum II GH SS Jubilee Plus Jubilee Marvel Tamarack GH GH LSD z Trials planted June 27. Plants dug and rated October 11. Data from 1 trial, 4 reps per trial, 3 plants per rep. y Number of nodes above the soil line with brown discoloration. x Scale of with 0=no crown discoloration, 0.5=beginning of discoloration, 1=crown rot present with black discoloration. w Scale of 1-3 with 1=no evidence of feeding, 2=less than 75% adventitious roots with feeding, 3=more than 75% roots with feeding.

11 Table 9. Root disease ratings of sugary sweet corn hybrids grown at the OSU Vegetable Research Farm, Corvallis, 2007 z. Primary root rot (%) Mesocotyl root rot (%) Adventitious root rot (%) Brown Root node y Crown rot x worm w Evita GH GH Coho GH Jubilee GH GH Tamarack GH LSD z Trials planted June 27. Plants dug and rated October 11. Data from 1 trial, 4 reps per trial, 3 plants per rep. y Number of nodes above the soil line with brown discoloration. x Scale of with 0=no crown discoloration, 0.5=beginning of discoloration, 1=crown rot present with black discoloration. w Scale of 1-3 with 1=no evidence of feeding, 2=less than 75% adventitious roots with feeding, 3=more than 75% roots with feeding.

12 Table 10. Root disease ratings of supersweet corn hybrids grown at the OSU Vegetable Research Farm, Corvallis, 2007 z. Primary root rot (%) Mesocotyl root rot (%) Adventitious root rot (%) Brown node y Crown rot x Root worm w Magnum II CSH YP SS Jubilee Plus GSS Marvel LSD 0.05 v ns ns ns z Trials planted June 27. Plants dug and rated October 11. Data from 1 trial, 4 reps per trial, 3 plants per rep. y Number of nodes above the soil line with brown discoloration. x Scale of with 0=no crown discoloration, 0.5=beginning of discoloration, 1=crown rot present with black discoloration. w Scale of 1-3 with 1=no evidence of feeding, 2=less than 75% adventitious roots with feeding, 3=more than 75% roots with feeding. v ns=non-significant.

13 Table 11. Correlation among root disease and yield traits for sweet corn hybrids grown at three locations, Corvallis, Oregon, z Mesocotyl root rot Adventitious root rot Brown Node Crown rot Root worm Gross Net Ear Length Ear Diam Kernel depth Primary root rot 0.77 *** 0.24 ** 0.18 * 0.35 *** 0.10 ns ns 0.11 ns 0.01 ns ns Mesocotyl root rot ** 0.13 ns 0.29 ** 0.10 ns ns ns 0.02 ns 0.04 ns 0.05 ns Adventitious root rot *** 0.26 ** 0.24 ** * ns 0.04 ns ns ns Brown node *** 0.22 * * ** 0.10 ns * ** Crown rot ns ** *** * Root worm ns ** 0.08 ns 0.12 ns 0.05 ns Gross *** 0.14 ns 0.54 *** 0.47 *** Net * 0.11 ns 0.26 ** Ear Length ns Ear Diam *** z Significantly different at: + = 90%, * = 95%, ** = 99% and *** = >99.9% probability levels. ns = not significant.

14 Botany Veg su Veg sh Net Yield ( T/ A) GH 6377 Coho GSS 1477 GH 4927 GH 6462 GH 8267 GH 2171 Magnum II Evita GH 6487 Tamarack Marvel Supersweet Jubilee Plus CSH YP3-99 Jubilee LSD 0.05 Figure 1. Net yield for sweet corn hybrids grown at 3 locations, Corvallis, Oregon, Botany = Botany Farm, where both supersweet and sugary hybrids were grown; Veg su = Vegetable Farm sugary hybrid trial; Veg sh2 = Vegetable Farm supersweet hybrid trial.

15 Botany VF su VF sh Adventitious root rot (%) GH 4927 GH 2171 Tamarack Marvel Jubilee SS Jubilee Plus GH 8267 Magnum II GH 6487 GSS 1477 CSHYP3-99 GH 6377 Coho GH 6462 Evita Figure 2. Adventitious root rot of sweet corn hybrids grown at three locations, Corvallis, Oregon, Botany = Botany Farm where both supersweet and sugary hybrids were grown; Vegsu = Vegetable Farm sugary hybrid trial; Veg sh2 = Vegetable Farm supersweet hybrid trial.

16 Botany VF su VF sh No. brown nodes above soil GH 6487 Jubilee SS Jubilee Plus GH 4927 GH 6377 GH 6462 CSHYP3-99 GH 8267 Marvel Tamarack GH 2171 GSS 1477 Evita Magnum II Coho Figure 3. Number of nodes above the soil line with internal browning for sweet corn hybrids grown at three locations, Corvallis, Oregon, Botany = Botany Farm where both supersweet and sugary hybrids were grown; Veg su = Vegetable Farm sugary hybrid trial; Veg sh2 = Vegetable Farm supersweet hybrid trial.

17 Botany VF su Crown rot (%) Evita GH 6462 GH 6487 SS Jubilee Plus Jubilee GH 4927 Marvel GH 2171 CSHYP3-99 Tamarack GH 6377 Magnum II GH 8267 Coho GSS 1477 Figure 4. Crown rot rating for sweet corn hybrids grown at three locations, Corvallis, Oregon, Botany = Botany Farm where both supersweet and sugary hybrids were grown; Veg su = Vegetable Farm sugary hybrid trial. Crown rot rating was the same (1.00) for all hybrids in the Vegetable Farm supersweet trial..