Mid-season Cultivars Research Articles

COMPARISON OF SPRING FROST TOLERANCE AMONG DIFFERENT HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.) CULTIVARS

ISHS XXVI International Horticultural Congress: Berry Crop Breeding, Production and Utilization for a New Century COMPARISON OF SPRING FROST TOLERANCE AMONG DIFFERENT HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.) CULTIVARS

Genotypic differences for grain yield and nitrogen utilization in Indica and Japonica rice under Mediterranean conditions

The identification of the factors that determine grain yield and nitrogen utilization in rice production systems is necessary to optimize their productivity and reduce the pollution risk for the environment. A field study was conducted to analyze the various component traits that cause variation in grain yield, grain nitrogen yield and nitrogen utilization efficiency (NUE) of direct water-seeded Indica and Japonica rice, using yield and yield component analysis. Five rice cultivars, Olympiada and L-202 (Indica type) and Ispaniki A′, Melas and Dion (Japonica type), with contrasting traits were grown in a silty loam soil (Aquic Xerofluvents) in 1999 and 2000. Grain yield ranged from 6045 (Melas) to 8310 kg/ha (Olympiada). More than 50% of the total variation in grain yield among cultivars was explained by the variation in panicles per square meter, suggesting the importance of tillering ability of a given cultivar in obtaining high yields. The relative contribution of grains per panicle was moderate (35.2% in 1999 and 34.1% in 2000), while that of grain weight the lowest. Grain yield was significantly correlated with N concentration in vegetative parts at anthesis. NUE for biomass accumulation during grain filling period was generally similar or lower compared to that during vegetative period. Indica cultivars had lower NUE for biomass accumulation and higher nitrogen utilization efficiency for grain yield (NUE g) compared to Japonica cultivars, mainly due to the higher NHI. For a reliable comparison among cultivars, the agronomic traits of each cultivar should be taken into account. Short and late maturing cultivars had significantly higher NUE g than the tall and early or mid-season cultivars, respectively. NUE g was negatively correlated with grain and straw N concentration at maturity, suggesting that low grain or straw N concentrations may be indications of higher NUE g.

'Jintao', a Novel, Hairless, Yellow-fleshed Kiwifruit

'Jintao' is a new yellow-fleshed kiwifruit (Actinidia chinensis Planch) developed from the breeding program at the Wuhan Institute of Botany (WIB), in Wuhan, Hubei, People's Republic of China. 'Jintao' is a midseason cultivar that ripens three to four weeks before the standard commercial cultivar [A. deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson] 'Hayward'. It is sweeter than 'Hayward' and has a smooth skin. 'Jintao' was selected from A. chinensis and offers growers in warmer climates an alternative to 'Hayward', because of its higher productivity, better fruit quality, and improved heat tolerance. 'Jintao', which means golden peach in Chinese, is named in recognition of its yellow flesh and the common Chinese name, Mihou-tao, or monkey peach.

Occurrence of Botrytis cinerea and Monilinia laxa on nectarine and plum in Western Cape orchards, South Africa

The occurrence of grey mould (caused by Botrytis cinerea) and brown rot (caused by Monilinia laxa) in the major stone fruit regions in the Western Cape Province was studied over a 3-year period by sampling reject fruit from the Unifruco Quality Evaluation Scheme and from 11 stone fruit orchards. Flowers and fruit from the orchards were treated to facilitate disease expression by surface conidia and latent mycelia (unsterile vs. surface sterilised; untreated vs. paraquat-treated). B. cinerea was found to be the most important pathogen causing blossom blight and postharvest decay on stone fruit. The pathogen was most prominent on early and mid-season cultivars. Surface conidia and latent mycelia consistently occurred on fruit in each orchard, although at fluctuating levels. The amount of B. cinerea on fruits was generally higher during spring than summer. Disease expression on fruit was not governed by the amount of B. cinerea occurring on fruit, but by the ability of fruit to resist disease expression. Blossom infection did not contribute directly to postharvest grey mould. Brown rot was exclusively caused by M. laxa and no evidence was found that M. fructicola had been introduced into the Western Cape Province of South Africa. The pathogen was most prominent on the later maturing cultivars. Immature fruit were generally pathogen-free and disease expression only occurred on maturing fruit. Long-term latency therefore does not seem to play a prominent role in M. laxa fruit rot.

Dry matter and N accumulation and translocation for Indica and Japonica rice under Mediterranean conditions

Part of the dry matter and N accumulated by rice ( Oryza sativa L.) plants until anthesis is translocated to grain during the grain filling period. A field study was conducted to assess the dry matter and N accumulation and translocation of direct water-seeded rice and examine their association with grain yield. Five rice cultivars, Olympiada and L-202 (Indica type) and Ispaniki A′, Melas and Dion (Japonica type), with contrasting characteristics were grown in a silty loam soil (Aquic Xerofluvents) in 1999 and 2000. Cultivar dry matter translocation efficiencies ranged from 8.5 to 39.3% and N translocation efficiencies from 44.7 to 66.7%. Differences among Indica and Japonica cultivars in translocation efficiencies were found, but these differences depended mainly on the agronomic characteristics of each cultivar. Dry matter and N translocation were greater for short and late maturing cultivars compared to the tall and early maturing or mid-season cultivars, respectively. Greater amounts of dry matter and N content at anthesis resulted in a greater dry matter and N translocation to grain. Grain yield was positively and significantly correlated with dry matter and N translocation efficiency, suggesting that the sink strength could be involved in the translocation efficiency. The contribution of pre-anthesis accumulated reserves to grain weight ranged from 9.1 to 42.2%, indicating the importance of pre-anthesis storage of assimilates for attaining high grain yield of rice under Mediterranean conditions.

Susceptibility of Highbush Blueberry Cultivars to Larval Infestation by Rhagoletis mendax (Diptera: Tephritidae)

Eighteen highbush blueberry, Vaccinium corymbosum L., cultivars were evaluated for larval infestation by the blueberry maggot fly, Rhagoletis mendax Curran. Most cultivars were evaluated during 3 field seasons. Significantly fewer maggots were found in berries of early-ripening cultivars, ‘Earliblue’ and ‘Bluetta’, than in later maturing cultivars such as ‘Bluehaven’, ‘Coville’, ‘Darrow’, ‘Elizabeth’, and ‘Lateblue’. The oviposition period of R. mendax is synchronized with the ripening dates of mid-season cultivars (late July to early August) in Rhode Island. This results in more oviposition and higher larval infestations in mid- and late-season susceptible cultivars. Among the mid- to late-season cultivars, ‘Northland’ and ‘Herbert’ berries had consistently fewer maggots than other cultivars. These cultivars, along with Bluetta and Earliblue appear to be good candidates for inclusion into integrated pest management programs.

PEACH TEXTURE DURING RIPENING AFTER EXTENDED STORAGE

Peach texture during storage is affected by temperature, humidity, and oxygen level. Four cultivars, ‘Sentinel’, ‘Topaz’, ‘Parade’, and ‘Fairtime’, were stored at 0C for 28 days after which time texture tests were done for the next four days during the peach's ripening at 25C. A cylindrical peach specimen was penetrated with a wire probe installed in an Instron universal testing machine. From the force-displacement response, firmness parameters were determined and a fast Fourier transform frequency analysis was performed to determine the jaggedness of the curves. Effegi firmness, Instron peak force, and spectrum area changed the most during ripening. The lowest frequency ratio (0 to 0.19 Hz) changed more than any other frequency ratio during ripening. Significant decreases in Effegi firmness and in Instron peak force, steady state force, and frequency ratios were observed between the first and the second day of ripening but the changes were not significant thereafter. After one day of ripening, late season cultivars ‘Fairtime’ and ‘Parade’ were significantly less firm than ‘Topaz’. Most parameters indicated that ‘Sentinel’ an early season cultivar, was firm like ‘Topaz’, a mid-season cultivar. After two days, differences in firmness parameters among the four cultivars were not significant.

Production practices in Western Australia for wheats suitable for white, salted noodles

Wheat cultivars acceptable for the Noodle wheat segregation in Western Australia were compared with cultivars suitable for the Australian Standard White (ASW) grade over the period 1989–93. Yield and grain quality responses to sowing time, nitrogen fertiliser, soil type, and cropping history were examined to determine management practices most likely to result in wheat grain suitable for the production of white, salted noodles. Thirty experiments were conducted in the 300–450 mm average annual rainfall zone between Three Springs in the north (approx. 29° 30′S) and Newdegate in the south (approx. 33°10′S). The ASW cultivars, Spear, Kulin, and Reeves, outyielded the Noodle cultivars, Gamenya and Eradu, by 8–10% on average, but the yield difference was less at later sowings. The optimum sowing time was early May for most cultivars. The new cultivars, Cadoux (Noodle) and Tammin (potential Noodle, but classiffied General Purpose), tested in 1992 and 1993 in 12 experiments showed an optimum sowing time of late May, as did other midseason cultivars. Grain yields of May-sown crops were increased by 13 kg for every 1 kg of nitrogen applied, compared with 3 : 1 for June-sown crops. Previous legume history of the site and grass weed control in the crop also influenced the grain protein percentage. It was concluded that adoption of production guidelines that include sowing at, or near, the break of the season with about 40 kg/ha of nitrogen fertiliser, a rotation that includes 2-3 years of legume crop or pasture in the previous 5 years, and adequate grass weed control will result in an excellent chance (>80%) of producing grain proteins within the receival standards for the Noodle grade. Flour swelling volume (FSV), an indicator of noodle eating quality, was negatively correlated (not always significantly at P = 0·05) with grain protein percentage in 7 out of 8 experiments. FSV values were larger from sites located in the south of the study area and this appeared to be independent of protein and time-of-sowing effects. Small grain sievings (<2 mm) were increased by sowing after the end of May, especially in the longer season cultivars.

Influence of Training Systems on Tree Size, Yield, and Fruit Quality of 15 Peach Cultivars

A peach and nectarine cultivar and training trial was planted in 1989. Training methods were open center (OC) and central leader (CL). The orchard was divided into three sections for early, mid-, and late season peaches with 10 individual-tree replications. The following characteristics were measured from 1989 to 1994: trunk cross sectional area, fruit yield, number of fruit, and fruit color. Early season peaches, those ripening with and before `Salem' in the OC system had significantly greater TCSA at the end of the fifth growing season. At the end of the sixth growing season, however, there was a significant training cultivar interaction. There were no differences between the mid- or late season cultivars. Measurable yields were obtained in 1991 through 1993. In all years, greater yields per tree were observed from trees in the CL system, although not significantly different for the late season cultivars. `Redhaven' and `Newhaven' had the highest yields for the early season cultivars, `Glohaven' for the mid-season cultivars, and `Cresthaven' and Biscoe for the late season cultivars. Trees in the CL system tended to have higher tree efficiency than trees in the OC system. Fruit color at harvest varied by year and training system.

Ta Tao Peach Interstems Influence Cultivar Phenology, Vigor, and Fruiting in South Carolina

Twenty-six peach and six plum cultivars budded to 20–50 cm Ta Tao five or twenty-four interstems on Lovell rootstock were observed in four trials at two locations in South Carolina. The locations were in the Piedmont near Clemson and the Sandhills near Pontiac, S.C. The objective of growing peach cultivars on interstems was to delay scion phenology to reduce risk from late spring freezes. Data from these trials were collected from 1989 to 1996. Average bloom delay for peach cultivars on interstems was significant each year from 1991 through 1996 and ranged from 5 to 9 days later than the noninterstem controls. Bloom of plum cultivars on interstems was not significantly affected. Interstem peach trees had significantly smaller trunk cross-sectional areas and averaged from 32% smaller in 3-year-old trees to 35% in 7-year-old trees. Interstem trees also had fewer lateral vegetative budbreaks (i.e., blind wood). Fruit maturity was significantly delayed on most peach cultivars on interstems. Fruit of early cultivars (90 days past bloom) ripened 2–4 days later on interstems. Likewise, mid-season cultivars ripened 5–6 days later and late season cultivars (>130 days past bloom) 3-4 days later. Fruit size was smaller on interstem trees when trees were either inadequately thinned or drought-stressed.

Long-season wheats extend sowing opportunities in the central wheat belt of Western Australia

Wheat cultivars and crossbreds with different maturities were tested at a range of sowing times from 1989 to 1991 at 13 sites in the central wheat belt of Western Australia. The aim was to determine if long-season cultivars would allow sowing before mid May, the earliest period estimated by previous studies. Rainfall in the growing season ranged from 176 to 330 mm. Long season cultivars showed the potential to extend the sowing season from early May into late April without loss of yield. Mid-season cultivars reached their maximum yields from sowings in May and short-season cultivars yielded most from late May and early June sowings. The optimum flowering period for the study area over the 3 years was 2-22 September, a period similar to earlier estimates made using only short- and midseason cultivars. It was concluded that, despite considerable variability from year to year both within and between sites, the optimum flowering period did not vary greatly on average and was not greatly affected by the use of long-season cultivars. Sowing after the optimum time resulted in slightly increased grain protein percentages but losses in the value of grain yield would have more than offset increases in the value of grain protein. At the nitrogen rates used in the experiments (80 kg/ha), grain proteins over 11.5% [the minimum for the Australian Hard (AH) grade] were only achieved on average for the long-season AH cultivar Blade at sowing times later than its optimum for yield. The Australian Standard White cultivars, however, mostly achieved 10% protein, an acceptable minimum for that grade, from sowings made at their optimum time. Hectolitre weights fell below the delivery standard of 74 kg/hL in only 3 grain samples. These were all from short-season cultivars sown before their optimum time. Fifteen grain samples from 4 sites contained small grain sievings (2-mm slotted screen) above the delivery standard. Eleven of these samples came from cultivars sown outside their optimum sowing times.

Leaf development in relation to infection by Stagonospora nodorum and Septoria tritici in wheat

Disease and phenology were compared in 2 wheat cultivars (Aroona and Spear) differing in disease resistance and maturity, at early (April-May) to late (June) sowing dates in 1991 and 1992. The cultivars had similar rates of leaf development but the longer season cultivar Spear averaged up to one leaf more on the main stem than the midseason cultivar Aroona, depending on sowing date. The extra leaf production which delayed flag leaf emergence on Spear compared to Aroona at early sowings was associated with lower disease levels in 1991. The occurrence of leaf rust may have diminished this advantage in 1992. Resistance to Septoria tritici in Aroona did not affect disease progress compared to Spear. A comparison of disease over a segment of accumulated thermal time revealed that in 1991, under average seasonal conditions, the earliest sowing experienced the most disease. In 1992, above average late spring rainfall occurred and time of sowing had little influence on disease over the same segment of thermal time. We conclude that a cultivar appropriate for early sowing on the south coast should exhibit increasing leaf production in response to early sowing. This can result in a reduction of disease severity on the upper leaves through disease escape.

Resistance and associated yield losses from rust (Uromyces trifolii-repentis Liro) in midseason cultivars of Trifolium subterraneum L. var. subterraneum L. and var. yanninicum Katzn. et Morley

A field study was conducted to quantify the effect of rust on the herbage production and seed yield of 4 new midseason cultivars of Trifolium subterraneum (Denmark, Gosse, Goulburn, Leura) and to compare their performance with 8 current commercial cultivars. Leura, Gosse, and Goulburn were all resistant to rust, with Leura most resistant. Denmark was not resistant to rust, but was much less susceptible than Green Range and marginally less susceptible than Mt Barker. By the end of the season, rust had reduced herbage yield in Green Range, Junee, Karridale, and Seaton Park (32, 23, 22, 18%, respectively) but did not affect any new cultivar. Rust reduced the seed yields of all cultivars except Goulburn, Larisa, and Leura. Seed yields of Green Range, Woogenellup, Mt Barker, Seaton Park, Denmark, Esperance, Karridale, Gosse, and Junee were reduced by 75, 70, 58, 55, 49, 47, 40, 40, and 38%, respectively. Rust also reduced the size of seed in all cultivars except Goulburn.

Walnut Husk Fly (Diptera: Tephritidae) Pest-Free and Preovipositional Periods and Adult Emergence for Stone Fruits Exported to New Zealand

Walnut husk fly, Rhagoletis completa Cresson, adults were trapped in two of nine trap locations in walnuts in five counties in the San Joaquin Valley of California before the end of the pest-free period, 1 July 1992. Highest numbers of adults were collected in walnuts from 19 August through 8 October after early-season, midseason, and most late-season stone fruit cultivars had been harvested. Lowest numbers of adults were trapped in Kern County locations in the southern region of the San Joaquin Valley. Laboratory behavioral studies showed that earliest ovipositional punctures in walnuts occurred 9 d after and eggs were laid 11 d after adult emergence. The preovipositional period will reduce the risk of stone fruit infestations during atypical years when adults emerge before 1 July. Adults emerged from pupae reared in the previous year from peaches, nectarines, and walnuts, but no adults emerged from plums. The biological risk for accidental introductions of walnut husk fly into New Zealand through shipments of stone fruits from California is negligible.

A comparison of two mid-season and two late-maturing Satsuma mandarins with the standard industry cultivar ‘Silverhill’

Abstract The Satsuma mandarin (Citrus unshiu Marc.) cultivars ‘StuntFree’, ‘Tanikawa’, ‘Hayashi’, and ‘Ishikawa’ were compared with the standard industry cultivar ‘Silverhill’, over 7 years, at the Te Puke Research Orchard in the Bay of Plenty, New Zealand. ‘Silverhill’ proved to be the best cultivar, with fruit achieving soluble solids concentrations (SSC) of 9.3–9.8% and SSC/acid ratios (SSC:A) of 7.2–8.4. The mid-season cultivars ‘Stunt Free’ and ‘Tanikawa’ had a similar period of commercial maturity to ‘Silverhill’ but as they produced fruit of poorer quality and exhibited weaker tree vigour, they do not appear to have any commercial prospects. Fruit of the late-maturing cultivars ‘Hayashi’ and ‘Ishikawa’ were also of poor quality, with high acidity and low SSC: A ratios. Although mandarin fruit quality can be expected to be higher in districts with a warmer climate than Te Puke (and/or by the use of improved cultural techniques), it is unlikely thatthe late- maturing Satsuma cultivars ‘Hayashi’ and ‘...

Evaluation of new cultivars of triticale as dual-purpose forage and grain crops

Two newly registered cultivars of triticale, Tiga and Empat, were compared with existing commercial cultivars of triticale, cereal rye and forage oats, for grain yield and dry matter production. Their performance was evaluated at Armidale, New South Wales, over 3 years with varying defoliation regimes (uncut to grain yield, cut in late autumn, cut in autumn and winter, and cut in winter only). Phenological observations confirmed that Tiga and Empat were midseason cultivars, intermediate between Coolabah and Blackbutt oats. Autumn and winter forage production and organic matter digestibility of Tiga and Empat were equal to those obtained from Cooba and Blackbutt oats. Grain yields (up to 4.0 t/ha) of the highest yielding triticale cultivar (Empat) were equal to, or greater than, the best oats cultivar (Blackbutt). Generally, the highest winter growth rates, dry matter yield at maturity and grain yield were recorded from uncut plots, except in the early oats cultivar Coolabah which, in 1 experiment, lodged in spring if left undefoliated through autumn and winter. Cutting only in autumn had small effects (negative) on grain yields, but cutting in both autumn and winter reduced total dry matter yields at maturity by 30% and grain yields by 50%. Cutting only in winter resulted in higher vegetative forage yields than a double cut (autumn and winter), but the single winter cut subsequently produced lowest dry matter yields at maturity. The high grain yields of triticale were linked to rapid spring growth. Harvest indices of triticale cultivars were generally lower than those of the oat cultivars. The results indicate the potential of triticale, especially cv. Empat, as a dual-purpose forage and grain crop.

Response to sowing time of three contrasting Australian cultivars of oilseed rape (Brassica napus)

SUMMARYSerial sowings of three cultivars of oilseed rape were made from autumn (May) to spring (October) at two sites, one in the north and one in the south of Tasmania, in 1981. The highest seed yields at both sites exceeded 5 t/ha from early sowing, ranging down to c. 2 t/ha from late sowing at a site where irrigation was adequate and to < 1 t/ha where late-sown crops suffered from water stress. The midseason cultivar Marnoo gave the highest yields at both sites, resulting from a combination of substantial (800 g/m2) top growth before flowering, excellent seed survival, a long period for grain filling and high oil content. The early-flowering line RU1 made much less growth before flowering; while this was partly made up for in later growth, nearly as many seeds per pod being retained as in Marnoo, oil content was low. The later-flowering cultivar Wesbell made more growth before flowering than the other cultivars, but when sown early it tended to grow tall, lodge and lose many pods in the dense, tangled canopy. This, combined with generally fewer seeds per pod, resulted in a much less efficient crop in allocation of dry matter to seeds and oil. Wesbell failed to flower uniformly from the late sowings, indicating segregation for vernalization response. The many immature seeds at harvest gave a low overall oil content. All three cultivars responded to vernalization and longer photoperiod in a pot experiment. While photoperiod appeared to be the main factor controlling the development rate to flowering in the field, there were interactions with vernalization response andtemperature.

Increasing wheat yields in a high rainfall area of Western Australia

Average commercial wheat yields in the southern, high rainfall area of Western Australia have seldom exceeded 1.5 t/ha and wheat is not widely grown. However, the average annual rainfall and length of growing season (>400 mm and >6 months) are conducive to much larger yields. Thirteen factorial experiments with mid and long season cultivars (Aroona and Osprey), 2 levels of applied nitrogen (N) (40 and 80 kg N/ha), 2 seed rates (50 and 100 kg/ha) and with or without fungicide were conducted at 8 sites over 2 seasons. The experiment was done to investigate combinations of cultivar and agronomic practices suitable for increased wheat production in long season environments in Western Australia. Largest grain yields (>4 t/ha) were obtained where wheat followed a grass-free break crop, and the mid season cultivar was used with 80 kg N/ha and 100 kg/ha of seed. Increases due to cultivar and seed rate were more consistent than those due to N, and increases from application of fungicide were less consistent. It is suggested that the optimal wheat production 'package' will include sowing in May in rotation with a grass-free break crop, seed rate of about 100 kg/ha and, when all other factors are optimal, N rates of over 40 kg/ha. The greatest yield increases were associated with the sites where wheat followed a grass-free crop. Increases due to other factors were relatively smaller. Hectolitre weight and percentage of small grain (<2 mm) often reached levels that would have entailed downgrading in commercial deliveries. However, in the most productive crops where root and leaf diseases were minimal, these quality parameters were seldom deficient and grain protein contents exceeded 10% at yields of up to 4 t/ha.

Flowering times of wheats in south-western Australia: a modelling approach

The time of flowering is important for the yield of wheat crops in south-western Australia, where the risk of frost damage and the onset of drought can occur in the same month. Relationships to predict the time from sowing to flowering were derived by linear regression of duration on mean temperature and photoperiod for 11 cultivars. The models were tested against independent observations of flowering measured in time-of-sowing experiments conducted at five locations over three years. The model accounted for 71-95% of the variation in the independent observations of duration from sowing to flowering. The slopes of the regressions of observed versus predicted values were always less than 1.0, significantly so for four cultivars (P<0.01). The mean deviation of the predicted from the observed varied from 2 to 10 days, depending on the cultivar, site and year. The model was used to examine the effects of seasonal variation, sowing time and location on the flowering times of early, mid-season and semi-winter cultivars in south-western Australia. Predictions over sites, sowing dates and years demonstrated that widely differing developmental patterns may be required to exploit the range of environments and sowing dates in the Western Australian wheatbelt. The durations from sowing to flowering for mid-season and semi-winter cultivars were less affected by the variation in temperature than cultivars with rapid development patterns, and the variation in flowering times between cultivars was smaller at cool locations than at warm sites. The use of the model for farmers and breeders is indicated.

Coastal Russet: A mid-season Russet-skinned potato cultivar

Coastal Russet: A mid-season Russet-skinned potato cultivar