Open-pollinated Cultivars Research Articles

Hybrid rye as a good crop component to enhance yield stability in a winter cereal mixture

The knowledge on yield stability and variability of hybrid cultivars cultivated in a mixture with triticale over the years is limited. Therefore, a two-factorial experiment with the cropping system (pure vs. mixture) and the cultivar type (hybrid vs. open pollinated) as factors was conducted on chernozem soil in continental conditions (47°24′N, 7°19′E, 300 m a.s.l.) in three seasons to assess the effect of yield and yield stability of two cereal mixtures. Four approaches to yield stability calculations were used. Lower stability was noted for mixtures with open-pollinated rye cultivars compared with hybrid cultivars. The adjusted coefficients of variation (aCV) indicated that the yield was more stable in mixtures with the hybrid variety. The yield Stability Index Delta (<i>SI</i><sub>Delta</sub>), which provides information about yield stability across the years, depends on the mixture components and weather fluctuation. The highest value of <i>SI</i><sub>Delta</sub> was obtained for the hybrid cultivar in the mixture (<i>SI</i><sub>Delta</sub> = 2.95), compared to the open-pollinated rye cultivar in the mixture (<i>SI</i><sub>Delta</sub> = 0.47). The yield stability analyzed using linear regression (Y<sub>exp</sub><sub></sub> against Yobs for each crop mixture) indicated slope values less than one for the hybrid rye, suggesting higher mean grain yields in intercrops (observed yield) compared to the corresponding two sole crops (expected yield) across the three study years. The cultivation of the Palazzo hybrid rye in a mixture with triticale (cv. Borowik or Borwo) showed higher yield stability compared with that of the open-pollinated Amber cultivar. The study confirms that the inclusion of hybrid cultivars of winter cereals in mixed crops is justified by increased yield stability in comparison with open-pollinated cultivars. The use of hybrid rye as a component of mixed crops should be considered, as it shows higher productivity and greater yield stability than open-pollinated cultivars.

Genetic diversity and selection using an ideotype in a Formosa papaya population

Ideotype is a combination of traits to be sought in a breeding program, supporting the selection process. However, there must be sufficient genetic variability to be explored to ensure success in this process. Thus, this study aimed to evaluate the genetic diversity of a population of Formosa papaya from the cultivar Rubi Incaper 511, maintained by farmers, and the use of an index based on the genotype-ideotype distance for preserving the original traits of the cultivar. A population of 250 individuals, maintained for approximately 10 years, was evaluated for 13 quantitative morpho-agronomic descriptors. Genetic divergence was estimated from the dissimilarity matrix using the mean Euclidean distance, and the dendrogram was formed using the hierarchical method of unweighted pair groups method with arithmetic averages (UPGMA). The index based on the genotype-ideotype distance was used for plant selection, with the cultivar Rubi Incaper 511 being the desired ideotype. The new means of the selected individuals and the selection differential were obtained after this selection. The individuals had fruit mass ranging from 0.73 to 1.99 kg, soluble solids content between 9.63 and 12.68 °Brix, and number of commercial fruits per plant ranging from 23 to 90. The dendrogram divided the genotypes into five groups. The selected individuals exhibited favorable selection differentials for ten traits and were closer to the selected ideotype. The management of this population by the farmers proved to be efficient in maintaining the genetic variability of the cultivar, and the selection through the index based on the genotypeideotype distance can be used to restore the phenotypic pattern of open-pollinated cultivars.

Irrigation Management Strategies to Enhance Forage Yield, Feed Value, and Water-Use Efficiency of Sorghum Cultivars.

Water scarcity is a major obstacle to forage crop production in arid and semi-arid regions. In order to improve food security in these areas, it is imperative to employ suitable irrigation management techniques and identify drought-tolerant cultivars. A 2-year field experiment (2019-2020) was conducted in a semi-arid region of Iran to assess the impact of different irrigation methods and water deficit stress on forage sorghum cultivars' yield, quality, and irrigation water-use efficiency (IWUE). The experiment involved two irrigation methods, i.e., drip (DRIP) and furrow (FURW), and three irrigation regimes supplied 100% (I100), 75% (I75), and 50% (I50) of the soil moisture deficit. In addition, two forage sorghum cultivars (hybrid Speedfeed and open-pollinated cultivar Pegah) were evaluated. This study revealed that the highest dry matter yield (27.24 Mg ha-1) was obtained under I100 × DRIP, whereas the maximum relative feed value (98.63%) was achieved under I50 × FURW. Using DRIP resulted in higher forage yield and IWUE compared to FURW, and the superiority of DRIP over FURW increased with the severity of the water deficit. The principal component analysis indicated that, as drought stress severity increased across all irrigation methods and cultivars, forage yield decreased, while quality increased. Plant height and leaf-to-stem ratio were found to be suitable indicators for comparing forage yield and quality, respectively, and they showed a negative correlation between the quality and quantity of forage. DRIP improved forage quality under I100 and I75, while FURW exhibited a better feed value under the I50 regime. Altogether, in order to achieve the best possible forage yield and quality while minimizing water usage, it is recommended to grow the Pegah cultivar and compensate for 75% of soil moisture deficiency using drip irrigation.

Evaluation of Chili Nazla IPB as An Ornamental Chilli for Releasing Variety

Chili (Capsicum annuum L.) exhibits a wide range of variations in terms of crown shape, fruit shape, fruit color, leaf color, leaf shape, and taste. While chili is commonly known as a food plant, it also serves as an attractive ornamental plant. Specifically, ornamental chili plants are desired to possess specific traits, such as compact growth, high fruit yield, and a variety of fruit colors within a single plant. This study aims to comprehensively describe the quantitative and qualitative superiority of the Nazla IPB variety in terms of its characteristics. The research was conducted in the Leuwikopo Darmaga experimental garden's greenhouse, located in Bogor, utilizing a randomized complete block design with four replications. The Nazla IPB variety, which is an open-pollinated (OP) cultivar, stands out due to its short plant height, ranging from 17.83 to 26.42 cm, making it highly suitable for ornamental purposes. Furthermore, the chili plants of the Nazla IPB variety possess a compact crown shape, enhancing their visual appeal, coupled with their short stature (ranging from 21.83 to 26.69 cm). The primary distinguishing features of the ornamental chili variety Nazla IPB include: 1) the color of the leaves, which transition from green (Green 137 C) to purple (Purple N186 A); 2) the black color of the young chili fruit (Black 203 A); 3) the fruit shape of Nazla IPB, which can be described as moderately triangular; and 4) the fruit undergoes a color transformation from black to dark green and finally to red. Nazla IPB has potential to serve as an attractive decorative plant option.

Pomological evaluation and GT-biplot analysis of promising open-pollinated genotypes of apricot (Prunus armeniaca L.)

Apricot is an important stone fruit species with different cultivars cultivated worldwide. Therefore, breeding programs are necessary for developing new varieties with various fruit quality and sensory traits. The present study evaluated morphological and fruit-quality attributes of thirty-seven apricot genotypes selected from several Iranian and Italian open-pollinated cultivars together with Shahroudi cultivar (control) during two growing seasons (2019–2020) using the UPOV descriptor and GT-biplot analysis. The results showed great variability in fruit size among all apricot genotypes studied. Most genotypes showed medium-sized fruits while large and small fruits were observed in eight and four genotypes, respectively. The highest yield was recorded in G-464, G-432, G-588, Shahroudi and G-571. Genotypes G-432, G-464, G-571, G-573, and G-576 had higher fruit weight than Shahroudi. In addition, G-450 and G-553 had the highest TSS (18.2°Brix) and TSS/TA (25.4), respectively. The GT-biplot analysis revealed that fruit weight and dimensions along with pH and TSS could be indicators for selecting superior genotypes. According to the present study, G-464, G-571 and G-450 can be introduced as superior genotypes and it is expected that the inter-crossing of these three have the potential to produce cultivars with sweet fruit, high yield and large fruit size.

Determination of the optimal plant population and rapeseed genotype (Brassica napus L.) in western Iran

This study was conducted to determine the most suitable plant population and genotype of rapeseed at the Eslamabad-e-Gharb Research Station in western Iran during 2018-2020. The experiment was a factorial based on a randomized complete block design (RCBD) with three replications. Factors included four plant populations (20, 40, 60, and 80 plants m-2), and seven genotypes included four hybrids (Natalie, Rohan, Neptune, and Marathon) and three open-pollinated cultivars (Nafis, Nima, and Nilufar). The results show that the effect of the year was significant for all traits due to the difference in weather parameters over the two years of the experiment. ANOVA results shows that the effects of the plant population significantly affected plant height, the number of branches, the number of grains per pod, grain yield, grain oil, and oil yield. The effect of the genotype was also significant for all traits except oil yield. The effect of the interaction between the plant population and genotype on plant height, the number of branches, the number of grains per pod, the number of pods per plant, and 1000-grain weight was also significant. In general, open-pollinated cultivars at 60 plants m-2 and hybrid cultivars at 40 plants m-2 had higher grain yields.

ESTIMATING MAIZE EAR GRAIN YIELDS ON FARM

Crop growth modelling is one of the important sciences in field crop sciences for it helps to reduce time and effort in searching for a fact or result. This article was dealed with a formula to predict maize ear grain weight when plants still standing on farm. Two genotypes of maize were used in this trial, a hybrid of feed maize was used in 2018 and an open-pollinated cultivar of pop corn in 2019. Ear length and diameter were measured on 50 randomly taken plants of full seed – set before harvest .Ears were harvested later, air dried ,threshed and weighed, then yield adjusted to 15% moisture .Ears were considered as cylinder ,and volumes of each ear were calculated .Date of observed ear grain weights and their volumes were analyzed for their correlation and regression ,they were fit in both years .The expected ear grain weight in 2018 formula was: expected dry ear grain weight (g) = - 0.1342 + 0.4871 ear volume (cm3) and in 2019 , the formula was : expected dry ear grain weight(g) = +0.3509 + 0.4776 ear volume (cm3). Date of observed and expected dry ear grain weights was analyzed by t- test. The results showed high similarity between observed and expected ear weights, indicating that these two equations will be helpful to estimate dry ear grain weight of maize, while plants still on farm.

Multivariate techniques for identifying potential carrot hybrids

The adaptation of carrot cultivars to the environment is a fundamental factor for the cultivation. This study aimed to evaluate the agronomic potential of carrot genotypes cultivated in two periods by the hierarchical and optimization methods. The experiments were set as completely randomized block design. The treatments consisted of four experimental hybrids (Hybrid 8, 12, 14 and 17), three open-pollinated cultivars (Brasilia, BRS Planalto and Suprema), and a commercial hybrid (Verano), carried out at two cropping seasons. The unweighted pair-group using arithmetic averages (UPGMA), Tocher, and graphics of dispersion methods were applied. The UPGMA method and the graphic of dispersion enabled better separation of the genotypes evaluated in the growing seasons. The genotypes hybrid 12, cultivars Suprema and Verano presented a similar performance in both growing seasons. The cultivar Alvorada presented the greatest carrot yield (26.6 t ha-1) and leaf fresh mass (1538.6 g plant-1) in the spring-summer season, while hybrid 27 presents great potential for a great production (37.6 t ha-1) of carrots in the autumn season

The Influence of Flower Head Order and Gibberellic Acid Treatment on the Hydroxycinnamic Acid and Luteolin Derivatives Content in Globe Artichoke Cultivars.

Flower head orders and the use of GA3 (gibberellic acid) treatment could be two influencing factors determining the bioactive compound levels in artichoke, but little to no information is available about their effects. In this study, we have therefore evaluated the influence of these factors on the hydroxycinnamic acid and luteolin derivative levels in three categories of artichoke: Seed-propagated open-pollinated cultivars; vegetatively propagated cultivars; and seed-propagated hybrids. The hydroxycinnamic acids and luteolin derivatives were quantified by RP-HPLC-DAD. The average flower head weight was the lowest in tertiary heads and GA3-treated artichokes, followed by secondary and main heads. Moreover, the hydroxycinnamic acid and luteolin derivatives levels were significantly higher in tertiary heads than in secondary or main heads. In addition, the GA3 treatment significantly reduced the hydroxycinnamic acid content and, in contrast, improved luteolin derivatives levels. These effects depended on the flower head order and cultivar. Knowledge of the effects of flower head order and GA3 treatment is therefore key in order to achieve the greatest health-benefits from artichoke consumption.

Yield response of watermelon (Citrullus lanatus Thunb.) cultivars to varied fertilizer rates in Rwanda

The choice of cultivar and adequate nutrition are vital for good watermelon (<i>Citrullus lanatus</i>) production. This study evaluated the yield performance of four watermelon cultivars: ‘Sugar Baby’, ‘Crimson Sweet’, ‘Sukari F1’ and ‘Julie F1’ under four different NPK fertilizer rates: 50, 75, 100 and 125 % of the recommended dose (RD) (90:60:60 kg ha^-1 of Nitrogen (N): Phosphorus (P): Potassium (K). The experiment was laid out in a split-plot design, with cultivars in the main plots, fertilizer in the subplots and three replications. The experiment was conducted in two seasons: 2017A and 2017B at two sites; Karama and Rubona. A higher number of fruits per plant (5.1-5.8) was obtained with ‘Julie F1’ + 75 or 100 % of RD at both sites and in both seasons, followed by ‘Sukari F1’ + 100 % of RD and the open-pollinated cultivar A higher fruit weight (4.4-5 kg) was obtained with ‘Julie F1’ and ‘Sukari F1’ under 125 % of the RD. Plots planted with ‘Julie F1’ and treated with 75 % or 100 % of RD recorded higher fruit yield per plant (20.9-27.5 kg) and higher fruit yield per ha (104.2-137.3 t). From these results, it can be concluded that the high yield performance of watermelon in the study area can be obtained with ‘Julie F1’ using 75 % (67.5: 45: 45 kg ha^-1) of the recommended dose of NPK fertilizer.

Yield response of watermelon (Citrullus lanatus Thunb.) cultivars to varied fertilizer rates in Rwanda

The choice of cultivar and adequate nutrition are vital for good watermelon (<i>Citrullus lanatus</i>) production. This study evaluated the yield performance of four watermelon cultivars: ‘Sugar Baby’, ‘Crimson Sweet’, ‘Sukari F1’ and ‘Julie F1’ under four different NPK fertilizer rates: 50, 75, 100 and 125 % of the recommended dose (RD) (90:60:60 kg ha^-1 of Nitrogen (N): Phosphorus (P): Potassium (K). The experiment was laid out in a split-plot design, with cultivars in the main plots, fertilizer in the subplots and three replications. The experiment was conducted in two seasons: 2017A and 2017B at two sites; Karama and Rubona. A higher number of fruits per plant (5.1-5.8) was obtained with ‘Julie F1’ + 75 or 100 % of RD at both sites and in both seasons, followed by ‘Sukari F1’ + 100 % of RD and the open-pollinated cultivar A higher fruit weight (4.4-5 kg) was obtained with ‘Julie F1’ and ‘Sukari F1’ under 125 % of the RD. Plots planted with ‘Julie F1’ and treated with 75 % or 100 % of RD recorded higher fruit yield per plant (20.9-27.5 kg) and higher fruit yield per ha (104.2-137.3 t). From these results, it can be concluded that the high yield performance of watermelon in the study area can be obtained with ‘Julie F1’ using 75 % (67.5: 45: 45 kg ha^-1) of the recommended dose of NPK fertilizer.

Effect of the planting season on carrot cultivars growth and yield in the brazilian semiarid region

In regions with high temperatures, carrot cultivation is impracticable, as high temperatures tend to reduce yield and quality of the product. However, with the advent of summer cultivars, carrot cultivation in these regions has become viable. The aim of this work was to evaluate the performance of ten carrot cultivars in different planting seasons. The experiments were carried out at the Rafael Fernandes Experimental Farm of the Federal Rural Semiarid University (UFERSA). The experiments were carried out in May, June, July and August of 2017. The experimental design was a randomized block with ten treatments and four repetitions. The characteristics that were evaluated were the root classification (long, average and short roots); commercial, non-commercial and total yield; dry plant weight and root fresh weight. Both the planting season and the cultivar played important roles in agronomic performance throughout the experimental period. In May and June, the highest average yields and plant growth were obtained (43 and 45 t ha-1 yield, respectively). Hybrid cultivars showed better performance than open-pollinated cultivars in terms of yield. The Brasília, BRS Planalto, and Kuronan varieties showed poor performance in all the evaluated characteristics.

Population improvement and synthetic cultivar production in forage kale (Brassica oleracea L.)

Experimental results are brought together to demonstrate that forage kale population improvement involving full-sib and selfed families can be done on an annual cycle, followed by production of a synthetic cultivar. Furthermore, this new breeding method compares favourably with the two successful methods used to date, namely triple-cross hybrid cultivars from inbreeding and crossbreeding programmes and open-pollinated cultivars from population improvement programmes. The key findings were that natural vernalization of kale in south east Scotland occurred by mid-December so that plants could be pollinated in a glasshouse with heating and lighting by the end of February and seed harvested by the end of May. The resulting full-sib or selfed families could be assessed in a field transplant trial in the same year, from June to November, thus completing an annual cycle. Self-pollination resulted in shorter plants with lower fresh-weight, dry-matter and digestible organic-matter yields, and undesirably higher contents of S-methylcysteine sulphoxide, the haemolytic anaemia factor, and the goitrogenic thiocyanate ion. As a consequence of digestible organic-matter yield being reduced by as much as 22%, the estimated optimum number of selfed parents in a synthetic cultivar was four to eight. Synthetic cultivars are expected to yield as well as triple-cross hybrids as there was no reduction in yield when the latter were open-pollinated.

Genetic diversity structure of western-type carrots

BackgroundCarrot is a crop with a wide range of phenotypic and molecular diversity. Within cultivated carrots, the western gene pool comprises types characterized by different storage root morphology. First western carrot cultivars originated from broad-based populations. It was followed by intercrosses among plants representing early open-pollinated cultivars, combined with mass phenotypic selection for traits of interest. Selective breeding improved root uniformity and led to the development of a range of cultivars differing in root shape and size. Based on the root shape and the market use of cultivars, a dozen of market types have been distinguished. Despite their apparent phenotypic variability, several studies have suggested that western cultivated carrot germplasm was genetically non-structured.ResultsNinety-three DcS-ILP markers and 2354 SNP markers were used to evaluate the structure of genetic diversity in the collection of 78 western type open-pollinated carrot cultivars, each represented by five plants. The mean percentage of polymorphic loci segregating within a cultivar varied from 31.18 to 89.25% for DcS-ILP markers and from 45.11 to 91.29% for SNP markers, revealing high levels of intra-cultivar heterogeneity, in contrast to its apparent phenotypic stability. Average inbreeding coefficient for all cultivars was negative for both DcS-ILP and SNP, whereas the overall genetic differentiation across all market classes, as measured by FST, was comparable for both marker systems. For DcS-ILPs 90–92% of total genetic variation could be attributed to the differences within the inferred clusters, whereas for SNPs the values ranged between 91 to 93%. Discriminant Analysis of Principal Components enabled the separation of eight groups cultivars depending mostly on their market type affiliation. Three groups of cultivars, i.e. Amsterdam, Chantenay and Imperator, were characterized by high homogeneity regardless of the marker system used for genotyping.ConclusionsBoth marker systems used in the study enabled detection of substantial variation among carrot plants of different market types, therefore can be used in germplasm characterization and analysis of genome relationships. The presented results likely reveal the actual genetic diversity structure within the western carrot gene pool and point at possible discrepancies within the cultivars’ passport data.

Japanese Bulb Onion: Production, Consumption, and Cultivars

Abstract Bulb onion is an ancient vegetable crop that has been cultivated for at least 5,000 years. In Japan, this cultivation has only 150 years of history, but nowadays, it ranks fourth in total production, fourth in cropping acreage, and second in consumption among vegetables grown domestically. Until the 1970s, open-pollinated onion cultivars were predominantly cultivated throughout the country; they were selected mainly from old US cultivars. Over the past three decades, these open-pollinated cultivars have been replaced with F1 hybrid cultivars that offer higher yield, better disease resistance, uniformity at maturity, and high bulb quality. In this review, an attempt is made to characterize the commercial production and consumption of Japanese bulb onion as well as agronomic characteristics of representative cultivars.

Oil productivity and adaptability of new sunflower open-pollinated cultivars

Oil productivity and adaptability of new sunflower open-pollinated cultivars

Comparative study on in vitro micropropagation response of seven globe artichoke [Cynara cardunculus var. scolymus (L.) Fiori] cultivars: open-pollinated cultivars vs F1 hybrids

Globe artichoke [Cynara cardunculus var. scolymus (L.) Fiori] growing has gained commercial importance in recent years due to its consumption as food. It has also started to attract attention in pharmaceutics. Due to globe artichoke’s stated importance, growers need large amount of pathogen-free, healthy starting materials for production. Stated material will maximize the yield while minimizing the costs. Hybrid cultivars have uniform in height and maturity and could be harvested concurrently; on the other hand, an open-pollinated cultivar would have useful potential that could be smoothly produced locally at a lower cost. In vitro micropropagation enabling these goals as it serves large scale, fast, reliable and realistic alternative method to classic propagation via offshoots. The aim of the present study was to comparatively evaluate the micropropagation efficiency of two important local open-pollinated (OP) cultivars (‘Bayrampaşa’, ‘Sakız’) and five F1 hybrid cultivars (‘Olympus’, ‘Madrigal’, ‘Sambo’, ‘Green Globe’, ‘Imparator’), on the basis of total subcultures they were subjected to. Various plant growth regulators at various combinations were assessed for in vitro micropropagation and subsequent in vitro rooting. 3/4 basic MS medium supplemented with 0.05 mg L-1 BA + 0.005 mg L-1 IBA was determined as the best media combination for in vitro micropropagation, while 10.0 mg L-1 IAA + 1.0 g L-1 activated charcoal adding to 1/2 basic MS medium had positive effects on in vitro rooting. According to results, the micropropagation efficiency varied based on cultivar differences and number of subcultures regardless of being OP or F1 hybrid. The present study demonstrated that in vitro propagation of globe artichoke could be a valuable process for assessing mass propagation regardless of using F1 or OP cultivars. Considering the OP cultivars are cheap in terms of price in a comparison to F1 hybrid cultivars, OP cultivars could be also recommended to be used for in vitro mass propagation.

A Multi-Criteria Evaluation of the Effectiveness of Nitrogen and Sulfur Fertilization in Different Cultivars of Winter Rapeseed—Productivity, Economic and Energy Balance

This article presents the results of a three-year experiment involving a multi-criteria evaluation (productivity, economic and energy balance) of the effectiveness of nitrogen (N) and sulfur (S) fertilization in different cultivars of winter oilseed rape (open-pollinated, semi-dwarf hybrid, long-stem hybrid) grown in north-eastern (NE) Poland. The yield of the semi-dwarf cultivar was 11% lower than the yield of the long-stem hybrid cultivar and 18% higher than the yield of the open-pollinated cultivar. In all cultivars, N fertilization improved yields up to a rate of 180 kg ha−1 and up to a rate of 230 kg ha−1 in years with low precipitation in spring and summer. Seed yield increased in all cultivars in response to S fertilization at 40 kg ha−1. Higher rates of N fertilizer decreased the content of crude fat and glucosinolates (GLS) and increased the concentration of total protein in all cultivars. Sulfur fertilization increased the content of total protein (in long-stem cultivars) and GLS (in all cultivars). Production costs ranged from €542–624 ha−1 (≤130 kg N ha−1) to €619–697 ha−1 (≥180 kg N ha−1). The demand for energy in the production of winter rapeseed ranged from 14.5–19.3 GJ ha−1 (≤130 kg N ha−1) to 22.4–27.0 GJ ha−1 (≥180 kg N ha−1).

Mining for Candidate Genes Controlling Secondary Growth of the Carrot Storage Root.

Background: Diverse groups of carrot cultivars have been developed to meet consumer demands and industry needs. Varietal groups of the cultivated carrot are defined based on the shape of roots. However, little is known about the genetic basis of root shape determination. Methods: Here, we used 307 carrot plants from 103 open-pollinated cultivars for a genome wide association study to identify genomic regions associated with the storage root morphology. Results: A 180 kb-long region on carrot chromosome 1 explained 10% of the total observed phenotypic variance in the shoulder diameter. Within that region, DcDCAF1 and DcBTAF1 genes were proposed as candidates controlling secondary growth of the carrot storage root. Their expression profiles differed between the cultivated and the wild carrots, likely indicating that their elevated expression was required for the development of edible roots. They also showed higher expression at the secondary root growth stage in cultivars producing thick roots, as compared to those developing thin roots. Conclusions: We provided evidence for a likely involvement of DcDCAF1 and/or DcBTAF1 in the development of the carrot storage root and developed a genotyping assay facilitating the identification of variants in the region on carrot chromosome 1 associated with secondary growth of the carrot root.

Management practices that maximise gross margins in Australian canola (Brassica napus L.)

Farm gross margins for canola are directly tied to yield, yet growers miss out on ∼40−50% of water-limited potential yields (YW). Many factors including weather variability can limit returns on production expenditure and lead growers to moderate inputs that also limit yield. The purpose of this study was to identify management practices that growers could use most profitably under differing seasonal conditions. Canola crop yields were simulated with APSIM at seven diverse Australian locations in a factorial array of management practices including sowing date, sowing density, cultivar, rate of cultivar development and nitrogen fertiliser rate. The implication for growers of input costs for the different management combinations was evaluated in terms of the extent that costs were recovered (ratio of gross margins to variable costs) and magnitude of variable input costs for gross margins. A regression-tree data-mining approach was used to identify the most profitable and highest yielding combinations of management practices. Environmental conditions (defined here by combinations of date of sowing and ‘perfect knowledge’ of growing season rainfall) had greatest impact on gross margins and few profitable management practices could be identified unless environmental conditions were first accounted for. When crop management practices were tailored to rainfall and sowing date to maximize gross margins, yields were up to 2 Mg ha−1 greater than the average yield achieved by industry. Yield generally increased in response to increasing variable costs but gross margins tended to plateau; after this point higher variable input costs were matched but not exceeded by revenue from increased yield. Gross margins changed in response to individual management factors: for sowing date, gross margins decreased with progressively later sowings from mid-March. For N fertiliser rate in all sowing dates, it was more profitable to use higher N fertiliser rates for higher rainfall deciles, and to use lower N rates as sowing was delayed. Cultivars with slow to medium rates of development were most profitable for early sowings up to the end of April, except where rainfall was low (in low rainfall deciles or for locations in low rainfall zones). Hybrid and conventional open-pollinated cultivars had similar gross margins, which were greater than for the Triazine-tolerant open pollinated cultivar due to its lower yield potential. Selection of most profitable practices was enhanced with knowledge of seasonal rainfall, but time of sowing matched with rate of development and a non-TT-OP cultivar could be selected to maximise gross margins without knowledge of rainfall. Nevertheless, high costs of production may hinder the most profitable selection of management practices.