Wet Growing Conditions Research Articles

Establishment of alfalfa interseeded into corn in response to one cycle of selection and hybridization

AbstractIntercropping alfalfa (Medicago sativa L.) in corn (Zea mays L.) can improve forage production, but wet growing conditions and high corn yields adversely impact alfalfa establishment. Therefore, we evaluated breeding alfalfa specifically for intercropping by selecting surviving plants from previous alfalfa varietal evaluations under corn and assigning them to five polycrosses to form cycle‐1 synthetics. Pollen from four polycrosses was also used to generate hybrid seed using a male‐sterility system. Corn was planted in May, intensively managed, and harvested for silage during September at Arlington and Prairie du Sac Wisconsin during 2019. Parental, polycross, and hybrid alfalfa entries were interseeded as swards between corn rows. Two subplots within each whole plot were treated with prohexadione, fungicide, and insecticide (PFI) or left as nontreated controls. Competition from high yielding corn combined with 43% above average precipitation during the growing season contributed to complete stand failure of nontreated alfalfa. Application of PFI improved foliar health, increased root mass, and enabled alfalfa establishment. Following corn silage harvest average stand density of PFI‐treated polycross entries was 35% greater than parental entries (105 vs. 78 plants m−2); broad‐sense heritability was 0.54. Overall, PFI‐treated polycross and hybrid entries had similar stand densities after corn, but posthoc comparisons indicated two hybrids had twofold greater stand density than parental entries. These results indicate plant selection can be highly effective for developing polycross and hybrid germplasm with improved survival under corn. Our findings should stimulate further breeding work to improve alfalfa and other forages for use in intercropping systems.

Performance of a semi-glossy onion hybrid in certified organic onion fields infested with Thrips tabaci and bulb-rot causing bacteria

More than one-third of the certified organic farms that produce dry bulb onions in the USA are in the Great Lakes region, while onion thrips, Thrips tabaci Lindeman, and bulb-rot causing bacteria are important onion production constraints. Onion cultivars with semi-glossy foliage have been reported to support fewer thrips and suffer less thrips damage and therefore may provide a non-chemical option for thrips management. However, inconsistent results regarding efficacy of semi-glossy onions to reduce thrips densities have been reported in field studies. Bacteria causing bulb rot can infect onion plants through wounds in leaves, but the relationship between thrips damage and bacterial bulb rot disease needs further investigation. In this study, the performance of a semi-glossy onion hybrid, ‘USDA Maia’, was compared with the commonly grown waxy, thrips-susceptible cultivar ‘Bradley’ on certified organic farms in New York and Wisconsin from 2019 to 2021. Results indicated that thrips abundance was not different between ‘USDA Maia’ and ‘Bradley’. Bacterial bulb rot incidence in ‘USDA Maia’ was either similar or lower than the incidence in ‘Bradley’ in four of six trials, but higher in the other two. Marketable bulb yield in ‘USDA Maia’ was similar to yield in ‘Bradley’ in four of seven trials, but lower in the other three. Positive relationships between thrips density and bacterial bulb rot incidence occurred in one of three trials for both onion cultivars. Similarly, negative relationships between thrips density and marketable bulb yield only occurred in one of three trials, regardless of onion cultivar. ‘USDA Maia’ did not reduce thrips infestations as anticipated, but it was similar in susceptibility to bacterial bulb rot disease and produced similar large bulb yields as ‘Bradley’. While high thrips abundance can potentially increase incidence of bacterial bulb rot disease, wet growing conditions during bulbing was more important.

Establishment and First Year Yield of Interseeded Alfalfa as Influenced by Corn Plant Density and Treatment with Prohexadione, Fungicide and Insecticide

Interseeding alfalfa (Medicago sativa L.) into a silage corn (Zea mays L.) companion crop can increase the yield and profitability of forage production and reduce the risk of nutrient and soil loss from cropland, but unreliable establishment of alfalfa hampers the adoption of this practice on dairy farms. This study evaluated plant survival, foliar health, and dry matter yields of two alfalfa varieties when established in corn sown at populations ranging from about 47,500 to 100,000 plants per ha−1 and when treated with prohexadione (PHD), PHD followed by fungicide and insecticide (PHD-FI), or not treated with agrichemicals. The plant density of alfalfa during establishment was adversely impacted by above average precipitation and high corn populations, but substantially improved by PHD-FI treatment, which limited alfalfa etiolation, disease, and defoliation. First-cut dry-matter yields of interseeded alfalfa after corn were maximized at a stand density of approximately 200 plants m−2 or 850 stems m−2 and total first year yield exceeded conventionally spring-seeded alfalfa by 59 to 75%. Overall, our results indicated that PHD-FI treatment promoted good establishment and subsequent forage production of interseeded alfalfa. Applications of PHD-FI must, however, be fine-tuned, and additional management practices must be developed to ensure both good yields of corn silage and reliable establishment of interseeded alfalfa, especially during wet growing conditions.

Waxing and waning slacks: The changing ecohydrology of interdunal wetlands/slacks in a Lake Michigan coastal dune complex during rising Lake Michigan-Huron levels

Since 2016 we have studied the largest interdunal wetlands/slack lying within a deflated parabolic dune east of Lake Michigan. Geologic cross-sections show ∼ 15 m of sand and gravel beneath the dunes, creating an aquifer hydraulically connecting Lake Michigan-Huron (MH) with the water table/shallow groundwater influencing the slack. Lake Michigan-Huron (MH) water levels have risen ∼ 1 m from 2016 to 2020, increasing water levels within and around the slack ∼ 1 m. Color-infrared images and vegetation quadrat sampling show water appearing, then significantly expanding with the main slack and upland/dune vegetation transitioning to wetland vegetation in response to this rise. Monitoring well data show slack water levels rise in spring as Lake MH rises. Levels drop as the growing season begins while Lake MH continues to rise through summer. Short-term slack water level increases occur due to local rain events, but significant water level declines follow due to evapotranspiration. Slack water levels begin to rise again in late summer and into fall as the end of the growing season arrives, evapotranspiration decreases, and heavier, more frequent rain events occur. Together, these factors push slack water levels to their highest point of the year while Lake MH levels are decreasing. In late fall–winter, slack water levels drop in concert with Lake MH levels. Climate change effects, increased transpiration from higher temperatures, summer drought, and greater variability in lake level fluctuations, may make it more difficult to maintain wet growing conditions for hydrophytic vegetation. Hence, climate change poses risks to the existence of this imperiled ecosystem.

The influence of abiotic factors on forming grain quality of bread winter wheat in the conditions of the Donetsk region

Purpose. To establish the dependence of grain quality formation of bread winter wheat on the effect of abiotic factors in the conditions of the Donetsk region. Methods. It was field research supplemented by analytical studies, measurements, calculations and observations in accordance with common methods and methodological recommendations in crop production. The research was carried out on experimental plots in field crop rotation of the State Enterprise “Experimental farm “Zaboishchyk” of the DSAES NAAS”. The years of the research were different by agroclimatic conditions during grain formation and filling: 2014 was wet, 2015 was dry, and 2016 was the optimal for the annual rainfall. Results. Weather conditions had the greatest impact on test weight (79.8 %) and 1000 kernel weight (61.8 %). The most of 17 winter wheat varieties studied formed the maximum 1000 kernel weight under increased rainfall and humidity during period of grain filling. The highest 1000 kernel weight (44.6 g) has been recorded in the variety Ihrysta. This index was the most stable in the varieties Yuzovska and Ihrysta (coefficient of variation 2.9 and 2.1, respectively). The degree of influence of variety characteristics on gluten indices (both quantity and quality) was 72.0 % and 67.9 %, respectively. Grain protein content almost similarly depends on the conditions of the year, and on the characteristics of the variety. Under high moisture protein content decreased, but variation of this index was insignificant. The varieties tested were quite stable in protein content and gluten quality. The minimum variability on test weight, gluten content and 1000 kernel weight was in the variety Ihrysta, whereas on protein content in the variety Yuzovska. To evaluate several indices simultaneously it is advisable to use one typical dimensionless scale with binary conversion of response 1 and 0 (meets or does not meet the normative requirements). This makes it possible to determine the abiotic conditions of growing when grain of given variety meets the requirements of regulatory documents established. So, the grain of the varieties Ihrysta and Peremoha corresponded to normative requirements (the value of complex quality index is 1) regardless of agroclimatic growing conditions, and grain of the variety Yuzovska did only under optimal and wet growing conditions. Conclusions. It has been established that gluten indices (quantity and quality) essentially depended on the variety. Weather conditions had the greatest impact on test weight and 1000 kernel weight. The dependence of the grain protein content is almost the same both on the year conditions and on the variety characteristics. The transition to the using complex quality index allows determining under what abiotic conditions the grain of given variety meets normative requirements.

The Impact of Weather Conditions on Response of Sorghum Genotypes to Anthracnose (Colletotrichum sublineola) Infection

Rainfall is a major climatic factor influencing anthracnose development. In this study, 68 sorghum accessions were evaluated for anthracnose resistance under dry and wet growing conditions at the Texas AM AJEA, 6(4): 242-250, 2015; Article no.AJEA.2015.083 243 Colletotrichum sublineola isolates 30 days after planting. Under dry growing conditions, three accessions showed a susceptible response across replications, whereas 41 accessions exhibited susceptibility under wet growing conditions. Also, 15 accessions that showed variation in susceptibility across replications under dry conditions were rated as susceptible across replications under wet growing conditions. Nineteen accessions consistently showed a resistant response under both dry and wet growing conditions. There was no significant correlation between weather variables and anthracnose development during the dry growing season, suggesting that climatic conditions were unfavorable for disease development. In contrast, there was a significant positive correlation between total rainfall and anthracnose infection and moderately significant relationships between number of days with rain and minimum relative humidity, with anthracnose infection during wet growing conditions. These results indicate that frequency and cumulative rainfall, as well as relative humidity are critical factors for disease development.

Location, Seeding Date, and Variety Interactions on Winter Wheat Yield in Southeastern United States

In the Southeast, winter wheat (Triticum aestivum L.) is typically planted from late October to early December. However, grain yield is reduced by an interaction of weather, soil, and plant factors. From 2009 to 2012 a study was conducted at three locations in Alabama to evaluate the seeding date effect on yield and yield components of three cultivars. The AGS 2060, AGS 2035, and Baldwin cultivars were evaluated within four seeding dates at approximately 15‐d intervals. Results showed that grain yield, spikes per m2, and kernel weight declined linearly with seeding delay; however, the impact changed among years and locations within a year. The variability of kernels per spike was location specific, in the north delayed planting resulted in a greater number of kernels per spike while the opposite occurred at the central and southern locations. At most location–year combinations, seeding 2 to 4 wk later than the Extension’s best seeding date resulted in yield losses; especially if warm and dry conditions were prevalent during winter and spring months at locations with sandy loam soils. Under warm and dry growing conditions, the impact of delayed planting on yield and kernel weight was the greatest for Baldwin and AGS 2035 and least for the AGS 2060. In contrast, when cold and wet growing conditions were prevalent, there were not significant planting date differences on yield and yield components. Cultivar and seeding date should be selected on a location basis due to the plant interactions with soil and weather factors.

Lentil Performance in Response to Weather, No‐Till Duration, and Nitrogen in Saskatchewan

Increased soil N in no‐till (NT) systems can interfere with biological dinitrogen fixation (BNF), stimulate vegetative biomass, and affect harvest index (HI) and yield of lentil (Lens culinaris L.). In the black soils of Saskatchewan, the effects of short‐term (5–7 yr: ST) and long‐term (28–30 yr: LT) NT practices on lentil were investigated in two experiments from 2006 to 2008. One trial tested the effects of NT duration on plant N and yield of five cultivars; the second examined the response of a late‐maturing cultivar to NT duration at four rates of N fertilization. In both studies, average grain yield in 2006 and 2007 (warm seasons) was 21% greater than in 2008 (cool season), although total rainfall and plant N content was similar in 2007 and 2008. Average soil available N over the years was 23% greater in LT than ST, but the cultivars had 33% less N and 28% less yield in LT than ST in a dry year (2006), and similar performance in LT and ST in the wet years (2007 and 2008). The 60 kg N ha−1 treatment in the second trial diminished the yield difference between LT and ST in 2006. The only BNF measurement in 2008 showed that the cultivars fixed 10% less atmospheric N2 in LT than ST in this year. Overall, cool and wet growing conditions stimulate vegetative biomass and lower HI and yield of lentil, whereas a possible reduction of lentil BNF in NT systems is less likely to affect lentil yield.

Comparing apparent electrical conductivity measurements on a paddy field under flooded and drained conditions

Every growing season, paddy fields are kept both flooded and drained for a significant period of time. As a consequence, these soils develop distinct physico-chemical characteristics. For practical reasons, these soils are mostly sampled under dry conditions, but the question arises how representative the results are for the wet growing conditions. Therefore, the apparent electrical conductivity (ECa) of a 1.4 ha alluvial paddy field located in the Brahmaputra floodplain of Bangladesh was measured in both dry and wet conditions by a sensing system using the electromagnetic induction sensor EM38, which does not require physical contact with the soil, and compared both surveys. Due to the smooth water surface under wet conditions which ensured increased stability of the sensing platform, the results of the survey showed considerably reduced micro-scale variability of ECa. Furthermore, the wet survey results more reliably furnished soil-related information mainly due to the absence of soil moisture dynamics. The differences between ECa under wet and dry conditions were attributed to differences in soil texture, mainly the sand content variation having considerable effect on soil moisture differences when flooded following drainage. Accordingly, the largest differences between ECa under wet and dry conditions were found in those parts of the field with a large sand content. Hence, the conclusion was that an ECa survey on flooded fields has an added value to precision soil management.

Preemergence Herbicides Effect on Growth and Yield of Early-Planted Mississippi Soybean

The objective of this research was to evaluate the impact of full and reduced rates of PRE herbicides, applied alone or in combination, on growth and yield of selected April-planted soybean varieties in the lower Mississippi River alluvial flood plain. Field studies were conducted in 2001 and 2002 at Stoneville, MS, to evaluate the effects of preemergence (PRE) herbicides on growth and yield of early-planted soybean. Main plot factor was PRE grass herbicide. Sub-plot factor was PRE broadleaf herbicide. Sub-sub-plot factor was soybean variety. Soybean injury 8 weeks after treatment (WAT) in 2001 under cool and wet growing conditions ranged from 11 to 31% when PRE broadleaf herbicides were applied alone. Pendimethalin alone caused 31% soybean injury 8 WAT. Soybean injury with PRE combinations of pendimethalin at 1120 g ai/ha and broadleaf herbicides ranged from 29 to 49%. Soybean injury with flumioxazin alone was 26 to 31% compared to 38 to 49% with mixtures of S-metolachlor and flumioxazin. Conditions after planting were warmer and drier in 2002 than 2001, but all herbicide treatments still resulted in noticeable soybean injury. Soybean injury from PRE broadleaf herbicides tended to be less with the sulfonylurea-tolerant soybean (STS) variety, especially in 2001. Averaged across PRE grass herbicides, soybean yield was reduced both years by metribuzin at 694 g ai/ha and sulfentrazone + chlorimuron at 231 + 38 g ai/ha. Averaged across PRE broadleaf herbicides, pendimethalin reduced soybean yield 4% in 2001 and S-metolachlor reduced soybean yield 3% in 2002.

Interaction of Flumioxazin with Dimethenamid or Metolachlor in Peanut (Arachis hypogaea L.)1

Abstract Field studies were conducted in various peanut growing regions of Texas and Georgia to study peanut response to flumioxazin alone or in combination with dimethenamid or metolachlor. In south Texas during 1997, flumioxazin plus metolachlor resulted in greater than 45% peanut stunt, while flumioxazin plus dimethenamid caused ≤20% peanut stunt. This stunting was attributed to cool, wet growing conditions. Peanut yields in flumioxazin plus metolachlor-treated plots were reduced 58% from peanut in the non-treated check. In 1999 and 2000, flumioxazin plus dimethenamid or metolachlor resulted in 15% or greater peanut stunt, but stunting was not constant across weather conditions or locations. In west Texas and Georgia no peanut stunting with flumioxazin was noted. At the Levelland, TX location, flumioxazin at 0.07 kg/ha plus metolachlor at 1.1 kg/ha reduced peanut yield 32% when compared with the non-treated check; while at the Pearsall, TX location, metolachlor or dimethenamid at 1.1 kg/ha, flumioxazin at 0.07 kg/ha plus dimethenamid at 1.5 kg/ha, and flumioxazin at 0.1 kg/ha plus dimethenamid at 1.1 kg/ha reduced peanut yield 24 to 48% when compared with the non-treated check. No yield reduction was noted in Georgia.

First Record of Botrytis Flower Blight Caused by Botrytis cinerea on Geraldton Waxflower in South Africa.

Geraldton waxflower (Chamelaucium uncinatum Schauer, family Myrtaceae), indigenous to western Australia, is cultivated commercially in South Africa as a cut-flower crop and exported to markets in the Northern Hemisphere. In September 2000, disease symptoms were observed on 4-year-old plants in a commercial orchard of C. uncinatum cv. Ofir in Philippe, in the Western Cape Province. The base of the petals and the calyxes of the waxflowers showed brown necrotic lesions. Eventually the calyx and all the petals turned brown, and the flowers shriveled and abscised. B. cinerea Pers.:Fr was consistently isolated from affected petal and calyx tissues. When placed in a moist chamber, conidia and mycelia formed on the surface of dead and infected tissue. Koch's postulates were confirmed by spraying flower stems of C. uncinatum cv. Ofir with a spore suspension (1 × 106 conidia per ml). Inoculated flower stems were placed in a bottle filled with water and enclosed in transparent plastic bags for 24 h at 21°C. Typical symptoms developed on the petals and calyx within 3 days after inoculation. B. cinerea was reisolated from affected tissues. Botrytis flower blight or gray mold, causing a flower petal disease, has been recorded on C. uncinatum in Australia (1), but this is the first record of Botrytis flower blight of C. uncinatum in South Africa. Because Geraldton waxflower is a major cut-flower crop grown for export, this disease can cause significant losses to the industry, especially under cool, wet growing conditions. Reference: (1) A. Tomas et al. Aust. Plant Pathol. 24:26, 1995.

First Report of Botrytis Blight, Caused by Botrytis cinerea, on Hibiscus in South Africa.

Roselle (Hibiscus sabdariffa L.) is an annual herb grown in China, Thailand, Mexico, and Africa. Different plant parts are used for cold and hot beverages, food ingredients, edible oil, and medicinal properties. In May 1999, a disease was observed in a commercial field of 6-month-old H. sabdariffa plants in Eshowe, KwaZulu-Natal, South Africa. Stems of diseased plants had brown, sunken lesions covered with green-gray spore masses. Infected stems collapsed. Lesions initiated on stems expanded rapidly under cool, humid conditions. In some cases, lesions developed on the flower stalk and expanded to the calyx, causing death of the calyx. Leaves had no lesions or sporulation, but as stem blight progressed, leaves wilted and fell off. Botrytis cinerea Pers.:Fr. (1) was consistently isolated from affected stem and flower stalk tissues. The pathogen produced profuse conidia and mycelia on the surface of dead and infected stems and calyxes, which resulted in a moldy gray appearance. The average size of conidia produced on naturally infected stems ranged from 5.5 to 8.0 × 6.0 to 13.0 μm (average 6.5 × 9.2 μm). On potato dextrose agar (1-month-old culture), conidia ranged from 5.0 to 9.5 × 6.5 to 12.5 μm (average 7.3 × 8.7 μm) based on 50 spore measurements. Microsclerotia were round or irregular and ranged from 1.2 to 3.0 × 1.0 to 2.5 mm (average 2.1 × 2.0 mm). Koch's postulates were confirmed by spraying potted, 6-month-old H. sabdariffa plants with a spore suspension (1 × 105 conidia per ml). Inoculated plants were enclosed in transparent plastic bags for 7 days at 15 and 20°C (night and day) in a glasshouse. Typical symptoms developed on stems and calyxes within 7 days after inoculation. B. cinerea was reisolated from affected tissues. Botrytis gray mold blight has been recorded on H. rosa-sinensis L. and Hibiscus sp. in Florida (2), but this is the first report of Botrytis blight on Hibiscus spp. in South Africa. Because the disease can result in plant death, Botrytis blight may have a significant impact on the establishment and yield of this crop in the field, especially under cool, wet growing conditions.

First Report of Botrytis Blight, Caused by Botrytis cinerea, on Hibiscus in South Africa

Roselle (Hibiscus sabdariffa L.) is an annual herb grown in China, Thailand, Mexico, and Africa. Different plant parts are used for cold and hot beverages, food ingredients, edible oil, and medicinal properties. In May 1999, a disease was observed in a commercial field of 6-month-old H. sabdariffa plants in Eshowe, KwaZulu-Natal, South Africa. Because the disease can result in plant death, Botrytis blight may have a significant impact on the establishment and yield of this crop in the field, especially under cool, wet growing conditions. Posted 10 June 2000.

Genetic Mapping of Quantitative Trait Loci in Maize in Stress and Nonstress Environments: I. Grain Yield and Yield Components

The utility of restriction fragment length polymorphisms (RFLPs) in detecting quantitative trait loci (QTL) in maize (Zea mays L.) populations has been established. Conflicting results have been reported on the ability to consistently detect the same QTL across environments. Grain yield is considered to be highly polygenic and strongly influenced by the environment. QTL mapping studies conducted in contrasting environments might increase our understanding genotype × environment interactions and improve selection response in maize breeding. Our objectives were to compare the QTL for grain yield and yield components detected in two diverse environments in an elite, adapted maize population and to investigate the relationship among the genetic factors controlling these traits. A population of 150 F2:3 lines was produced from the cross of elite inbreds Mo17 and H99. The lines per se were evaluated for 2 yr at the same location. The first year had relatively average growing conditions, but the second year with cool, wet growing conditions provided a stress environment. Grain yield and yield components were measured on replicated progeny each year. By using a linkage map of 111 loci, QTL determinations were made in the two environments and in the mean of the two environments. About 50% of all QTL detected across environments were detected in both enviromnents. These QTL were consistent in the magnitude of their effects and parental contribution. Determinations of QTL in the mean of the two environments were most informative in that 74% of all QTL and 82% of the QTL detected in each of the individual environments were identified in the mean environment. Most QTL identified regions associated with two or more yield components in a manner consistent with correlations among traits and parents phenotypes.

Response of four annual broadleaf crops to simulated imazamethabenz spray drift

Field experiments were conducted from 1992 to 1994 in southern Manitoba to investigate the tolerance of buckwheat, canola, field pea and lentil to simulated imazamethabenz spray drift. Imazamethabenz was applied at 0, 7.5, 15, 30, 60 and 120 g a.i. ha−1 2 wk after crop emergence when buckwheat and canola were in the two- to three-leaf stage and lentil and field pea vine length was 10 cm. Application rates corresponded to 0, 1.6, 3.1, 6.3, 12.5 and 25% of the recommended field rate for control of wild oat (482 g a.i. ha−1). At the dosages examined, buckwheat and canola leaf area index 2 and 4 wk after treatment, seed yield and thousand seed weight were unaffected. Lentil and field pea were severely injured by 60–120 g a.i. ha−1 of imazamethabenz. Injury consisted of foliar chlorosis, stunting, increased basal branching and delayed maturity. Field pea and lentil yields were reduced only at 60–120 a.i. ha−1 of imazamethabenz. At these rates, yield losses were 27–59% and 25–76% for lentil and field pea, respectively. Yield losses differed among years, with the highest percentage yield losses occurring under cold, wet growing conditions. Key words: Buckwheat (tame), canola, pea (field), lentil, spray drift, sublethal rates

Seed yield and yield stability of determinate and indeterminate autumn-sown white lupins (Lupinus albus) grown at different locations in France and the UK

SUMMARYThe seed yields and maturity dates of an indeterminate cultivar (Lunoble) and a determinate line (CH304/70) of Lupinus albus L. were measured at three locations in France (Lusignan, Dijon and Gotheron) and at Rothamsted, UK, in 1989/90 and 1990/91. Different combinations of sowing dates, plant densities and irrigation treatments were tested at some sites.Averaged over all sites, CH304/70 yielded more than Lunoble (3·26 v. 2·98 t/ha) but there were significant genotype × location interactions for yield and date of maturity. Both genotypes gave similar yields at the three locations in France (3·13 and 3·06 t/ha, respectively). But under the cool and wet conditions at Rothamsted, CH304/70 yielded 4·26 t/ha compared with only 202 t/ha for Lunoble. Yields of CH304/70 were more stable than those of Lunoble across locations and years; the coefficients of variation about the overall means were 14 and 22%, respectively. CH304/70 ripened up to 16 days sooner than Lunoble in France, and 6 weeks earlier than Lunoble in the cooler conditions of the UK.In wet growing conditions (Lusignan 1989/90, Rothamsted 1990/91) Lunoble had increased vegetative growth which decreased the proportion of yield produced by mainstem pods and correspondingly increased the proportion borne on second-order branches. This continued branching also delayed harvest, especially in the UK where the crop was not harvestable until early November. In these conditions, CH304/70 outyielded Lunoble at Lusignan (3·4 v. 2·7 t/ha) and at Rothamsted (4·3 v. 2·0 t/ha) and was harvested acceptably early in mid-September. However, under warm, dry conditions, Lunoble produced only one order of branches at Gotheron and two orders at Lusignan in 1990/91. At Gotheron, both genotypes matured at the same time but CH304/70 yielded slightly better (3·1 v. 2·8 t/ha) because it produced a higher proportion of its yield on the mainstem, whereas at Lusignan, Lunoble yielded better than CH304/70 (4·1 v. 3·4 t/ha) because of extra yield from pods on second-order branches.CH304/70 produced seeds of larger mean size and had greater stability of seed size across years and locations than Lunoble did. This was apparently the result of CH304/70's determinate structure, in which c. 75–100% of the yield was from pods on the mainstem and first-order branches, whose seeds were larger and less variable in size than those from pods on higher-order branches of indeterminates.The development of autumn-sown genotypes with a determinate structure that combine adequate yield and early harvest under cool conditions offers the prospect of extending the geographical range of lupins, grown for grain, both to the cool regions of northern Europe and to hotter and drier regions in southern Europe where summer drought limits the yield of conventional indeterminate types.