April Sowing Research Articles

チコリ（Ｃｉｃｈｏｒｉｕｍ ｉｎｔｙｂｕｓ Ｌ．）軟白葉の工場生産を前提とした根株養成適期

In order to establish a hydroponic blanching system for culturing Witloof chicory in Japan, seeds of five F1 hybrids were sown in different months to determine the optimum time of sowing. In 1991, seeds were sown in a cell tray and transplanted one month later. In 1992, seeds were sown directly in an open field.The minimum temperature in the greenhouse in March 1991 was 10°C. In the days following planting in the field in mid April, the average minimum temperature was 10°C, although for several days the minimum temperature fell to 2.4°C. In 1992, from mid April to May, minimum temperatures of less than 10°C were maintained for 6consecutive days.The bolting ratio 5 to 6 months after sowing was lowest for seeds sown in March and highest for seeds sown in April. Sowing after July resulted in only a small amount of bolting. The late season cultivars had a tendency to be late in flowering. In the transplanted culture in 1991, enlargement growth of the underground part of the plant was suppressed for plants sown in March and August compared with those sown in June. However, in 1992, there was no difference in root enlargement growth between plants sown in June and August. In 1991, enlarged roots of plants that were sown in June and that were cultured for 5 or 6 months were used for hydroponic blanching culture. The enlarged roots that were cultured for 5 months produced small (20-30g) blanched leaves (chicons), but those cultured for 6 months produced rather bigger chicons (50-80g). In 1992, enlarged roots of plants that were sown in June or August and cultured for 5 months were used for blanching culture. For three of the five cultivars, the plants sown in August produced bigger chicons (ca. 120g). For the other two cultivars, the chicon productivity was not affected by the sowing month.

A gene complex for annual habit in sugar beet (Beta vulgaris L.)

Annual habit in sugar beet has been shown to be controlled by a dominant gene, B, which induces bolting under long days without the cold requirement usually essential for biennial cultivars. The induction of bolting by B, however, is often influenced by both environmental and genetic factors. We studied the genetic basis for bolting suppression, caused by delayed planting, in lines derived from a cross between annual and biennial lines. The F2 progeny of a late-bolting F1 plant yielded an unexpected segregation ratio of annuality from monogenic inheritance when planted in late May, there being an excess of non-bolting biennials, although the expected segregation was observed in the late April sowing. Bolting suppression was caused by restricted daylengths due to delayed planting because the segregation was normal under artificially induced long days. The analysis with Idh1, an isozyme marker proximal to B, demonstrated that heterozygous B plants were more susceptible to bolting suppression due to delayed planting than homozygous B plants. The results suggest that bolting suppression was controlled by a number of genes responsible for long daylength requirement, one of which was closely linked to B and formed a gene complex for annuality. The annual habit was controlled singly by B under long days but modified by the genes for long daylength requirement under restricted daylengths.

A Study on to Determine of Favorable Sowing Date for Dry Bean in Tokat Ecological Conditions

The aim of this study whic was carried out in Tokat ecological conditions was to determine favorable sowing date for dry beans. The experiments were done in 1992 and 1993 years and Tokat Yerli, Horoz and Dermason cultivars were used. Sowing dates were 1 st and 23 rd April, 13 rd May and 7th June in the first year, 3 rd and 24 th April, 15 th May and 6th June in the second year. Trials were conducted split plots in randomized blocks with four replications. Cultivars were found differences statistically for plant height, the number of pod per plant, pod length, the number of seed per pod, the number of seed per plant and 1000 seed weight, while were not found differences statistically for biological yield, seed yield per plant, harvest index and seed yield per decare. Plant height, pod length, seed yield per plant, harvest index and seed yield per decare in both years and the number of seed per plant were influenced only the first year by showing. Total plant yield, the number of pod per plant, the number of seed per pod and 1000 seed weight were not influenced by sowing dates. The highest seed yield in per decare was obtained at 23-24 th April sowing dates.

The effect of seed pretreatment and sowing date on the nursery emergence of Sitka spruce (Picea sitchensis [Bong.] Carr.) seedlings

Sitka spruce seeds which had been: (1) untreated (U), (2) prechilled (P), or (3) prechilled and then redried and stored for 16 months (R), were sown into progressively warmer seed beds on four dates at monthly intervals from March to June. At each sowing date, samples of seed were germinated in the laboratory at optimum (20°C) and sub-optimum (10°C) temperatures. Prechilling and prechilling + redrying both increased the rate and total amount of germination compared with untreated seed at each test temperature. However in the nursery, the beneficial effects of pretreating Sitka spruce seed were restricted to sowing in March and April when soil temperatures were sub-optimal for the germination of untreated seeds. Pretreatment resulted in rapid seedling emergence at soil temperatures between 10°C and 15°C, whereas untreated seed germinated slowly and seedling emergence continued until high soil temperatures in June killed ungerminated seeds. The pattern of seedling emergence from the redried seed was similar to that from the prechilled seed, except for a lag in the start of seedling emergence probably due to the extra time needed for redried seed to imbibe water in the seed beds. Thus redrying caused insignificant loss of seed performance on the nursery. Seed sown in May and June experienced average temperatures close to the optimum for germination of 20°C, however daily maxima regularly exceeded 35°C resulting in the cessation of seedling emergence in all three seed treatments, and the loss of newly emerged seedlings. Periods of warm weather from June onwards were the main factors limiting the final number and size of seedlings.

Growth and yield response of barley and chickpea to water stress under three environments in southeast Queensland. II. Root growth and soil water extraction pattern

Root growth and water extraction of two barley cultivars, Corvette (early maturing), Triumph (late maturing) and one cultivar of chickpea (Amethyst at Redland Bay and Borwen at Hermitage) were compared under three environments: April sowing and July sowing at Redland Bay and June sowing at Hermitage Research Station, south-east Queensland. This work was designed to explain differences in dry matter production in terms of root growth and water uptake during the crop growth, which relied only on stored soil moisture. In the April sowing where all crops grew well during the early stages of growth, decline in soil water with time for the whole profile was similar among all crops. In the winter sowings (June, July), total water use was less in chickpea than in barley, particularly during early stages when chickpea growth was poor. Water extraction patterns of two barley cultivars were similar in all experiments, though the late-maturing Triumph extracted slightly more water than early maturing Corvette towards maturity. Water extraction front velocities of the three crops were similar in each experiment. At Redland Bay, the water extraction front velocities varied from 1.4 to 1.6 cm day-1 in the April sowing and 2.3 to 2.4 cm day-1 in the July sowing, while they varied from 2.0 to 2.3 cm day-1 at Hermitage. However, descent of the water extraction front commenced later in chickpea than in barley when sown in winter months, and this resulted in lower total water use in chickpea, particularly at Hermitage. In both sowings at Redland Bay total root length increased rapidly to about 60 days after sowing in barley, whereas the increase was slower in chickpea. Root length density was high in the upper soil layers, and this was associated with high extractable soil water. In deeper layers both root length density and extractable soil water decreased. For a given root length density chickpea extracted more water than barley. These results indicate that the differences in root growth and water extraction by the two barley crops were rather small and were unlikely to be the reason for the differences in total dry matter production. Chickpea on the other hand appeared to be susceptible to low temperatures during early stages of growth, and this caused poor growth of both shoots and roots.

Growth and yield response of barley and chickpea to water stress under three environments in southeast Queensland. I. Light interception, crop growth and grain yield

Two barley cultivars (early-maturing Corvette and late-maturing Triumph) and one cultivar of chickpea (Amethyst at Redland Bay and Borwen at Hermitage), were grown in well-watered and water stress trials in three experiments to determine how the effect of water stress on growth and yield of these crops was modified by other environmental conditions, particularly temperature. Two experiments (experiments 1 and 2) were conducted at one location (Redland Bay) with two times of sowing (April and July), while experiment 3 (June sowing) was conducted at Hermitage Research Station, which had much lower temperatures in winter. In water stress trials, rainout shelters were used to exclude rain from plots from crop establishment to approximately maturity. In both well-watered and water stress conditions, the barley crop produced a lower yield when sown in April than in mid-winter, as grain filling occurred in late winter/early spring, when radiation and temperature were low. Chickpea in the irrigated control, however, produced the lowest yield in the July sowing at Redland Bay, because of the rapid increase in temperature in spring which hastened maturity. In water stress trials chickpea produced the lowest yield at Hermitage, as water stress severely reduced crop growth after flowering. Early-maturing Corvette produced a higher grain yield than late-maturing Triumph in one water stress trial (experiment 1), when difference in maturity time was 40 days, but not in others when the difference in maturity was less than 15 days. In most crops, development of water stress was slow during early stages of growth, and severe stress developed after maximum light interception was achieved. In these cases, water stress had a small effect on light interception but a large effect on light use efficiency (total dry matter produced per unit of solar radiation intercepted). However, for the chickpea sown in April, water stress developed during leaf area expansion, and severely reduced light interception with little adverse effect on light use efficiency. The results thus suggest that whether water stress affects light interception or light use efficiency depends on the timing of water stress in relation to the canopy development.

Effect of sowing time on yield and agronomic characteristics of wheat in south-eastern Australia

The main environmental constraints to the yield of dryland wheat in south-eastern Australia are: a low and erratic rainfall throughout the growing season, the chance of frost at flowering time, and high temperatures during the grain-filling period. The aims of this work were threefold. Firstly, to determine which sowing period minimizes these constraints and results in the highest yields. Secondly, what is the optimum flowering time for a given sowing date so that maximum yield is achieved. The third aim was to determine whether any crop characteristic was associated with high yield or may limit yield in the different sowings. The experiments were conducted at three sites in New South Wales that were representative of dry (Condobolin) and cooler and wetter (Moombooldool, Wagga Wagga) sites in the south-eastern wheatbelt. In this study several sets of isogenic material, involving a total of 23 genotypes, that were similar in all respects except for flowering time, were sown early (mid-April and early May), normal (mid to late May) and late (June to mid July). Characteristics of the highest-yielding lines in each experiment are presented. The average flowering time of the highest yielding lines in all sowings had a range of only 12 days at the driest site, but a range of over 20 days at the coolest and wettest site. The optimum anthesis date (day of year, y) was related to sowing date (day of year, doy) at the cooler sites such that: y = 245+0.32 doy (r2 = 0.86) and at Condobolin, y = 253+0.19 doy (r2 = 0.91). Optimum anthesis date expressed in thermal time (�C days) after sowing (y) was related to sowing time (doy) as follows: y = 2709 -8-3 doy (r2 = 0.84). It is suggested that these relationships are likely to be quite robust and should hold true for similar thermal environments in eastern Australia. There was little variation in grain yield between the earliest sowing in mid-April (108 doy) and sowings throughout May (up to 147 doy). Grain yield declined 1.3% per day that sowing was delayed after late May. Aboveground biomass was substantially higher in early sown crops. However, this did not translate into higher yields. From the evidence presented it is argued that the principal reason that greater yields were not obtained in the early sowings, particularly in the April sowing, was the greater competition for assimilates between the growing spike and the elongating stem. It is suggested that a way of overcoming this competition is to genetically shorten the stems of winter wheats. This should capitalize on the considerable advantages in terms of water use efficiency that early sowing offers and result in greater yields. Barley yellow dwarf virus, although present at the cooler, wettest site in one year, was more frequent in the later sowings than in the early sowing and was not likely to have contributed to the lower than expected yields in the early sowings.

Seed and seedling studies of three Trifolium subterraneum var. brachycalycinum lines, in a predominantly summer rainfall environment

Field experiments were conducted in a predominantly summer rainfall environment to investigate burr burial, seed production, seed characteristics, seedling emergence and survival, and the effects of time of sowing on 3 Trifolium subterraneum var. brachycalycinum lines (cv. Clare and 2 local lines). Each line produced more surface than buried burrs; surface burrs were 59% (range 56-62%) of the total number of burrs recovered and produced 59% of the total seed number. Numbers of seeds per burr were similar for surface and buried burrs, however, buried seeds were 0.97 mg heavier (P<0.05) than surface seeds. Storage for 5 months at 25/60�C decreased hardseed content of surface seed by 50% and buried seed by 70%. Surface and buried seeds stored at 25/25�C for 3 months prior to sowing in trays had a total emergence of <10%, compared with 70% emergence for seeds stored at 25/60�C before sowing. These emergence differences reflected their levels of hardseededness. Numbers of seeds recovered from the soil were not significantly different among lines, declining from about 4200 seeds/m2 after initial seed set to 150 seeds/m2 by the following winter, a 97% decrease. Seed production in the second year increased seed reserves to about 8730 seeds/m2. With no further seed production, levels had declined by 93% in June 1990 and by 99% in May 1991. These data confirm the importance of annual seed production for persistence. Total seedling emergence in summer-autumn accounted for only 10% of the estimated seed production in each year. Seedling survival in summer-autumn 1988-89 was 92.7%, more than double the survival in 1989-90. The effect of sowing time on flowering was always significant, with time to first flower being highest (196 days) for the earliest sowing in March (P<0.05), progressively decreasing (P<0.05) to 108 days for the latest sowing in July. In March, April and May sowings, inflorescence numbers on the first day of flowering were similar at about 120/m2, but increased markedly (P<0.05) for sowing in June or July. However, for the March and July sowings, number of inflorescences at the 9 November 1990 count, were lowest (P<0.05). May or June sowings had the highest number of burrs and seeds (P<0.05), indicating that these may be the best sowing times for maximum seed production in these Trifolium subterraneum var. brachycalycinum lines.

The effects of timing and duration of floods on growth of yound plants of Phalaris arundinacea L. and Urtica dioica L.: an experimental study

A pot experiment was performed with ypung plants of Phalaris arundinacea L. and Urtica dioica L. cultivated from seeds sown in April. Seedlings of both species were flooded during the spring (May–June) or summer (June–August) or autumn (August–October). Flooding in spring did not affect the survival of P. arundinacea seedlings but increased mortality of U. dioica seedlings. Summer flooding reduced the growth of rhizomes and tillering in P. arundinacea, while none of the U. dioica plants survived more than 4 weeks of summer flooding. Plants of P. arundinacea flooded in autumn had a higher dry mass than those grown in mesis conditions, but their growth terminated earlier. All plants of U. dioica survived the whole period of autumn flooding (9 weeks) but their dry mass decreased as a result of leaf and root mortality. The response of the two species to flooding is discussed in relation to their establishment in floodplain habitats.

Soil biodegradation of imazamethabenz‐methyl and its acid metabolite in wheat crops and in sugar beet replacement crops

Summary: Résumé: ZusammenfassungThe effect of three organic fertilizers, green manure, pig slurry, and cow manure on the rate of soil degradation of imazamethabenz‐methyl under field conditions was investigated in a wheat (Triticum aestivum) crop sown in November. The herbicide was applied in March, 5 months after incorporation into the soil of the fertilizers. The half‐life of imazamethabenz‐methyl in the soil was 35 days in control plots, and 55, 66 and 85 days respectively in plots treated with green manure, pig slurry, and cow manure. In the same plots the half‐lives of the sum of imazamethabenz‐methyl and its herbicide acid metabolite were 61,98,127 and 172 days, respectively. The organic fertilizers thus increased the soil persistence of imazamethabenz‐methyl and its acid metabolite, i.e. the product generated by hydrolysis of the methyl ester function of imazamethabenz‐methyl. Towards the end of the cropping period, residues of both compounds became low in both fertilizer‐treated and control plots. Soil degradation of imazamethabenz‐methyl was also studied in sugar beet (Beta vul‐garis) replacement crops sown in April into land treated in November of the preceding year (as could occur with a treated winter wheat crop which subsequently failed). The rate of degradation in the sugar beet replacement crop was about half that of the same treatment applied in spring wheat. Dégradation biologique dans le sol de rimazaméthabenz‐méthyle et de son métabolite acide dans des cultures de hlé et de betterave à sucre de remplacement L'effet de trois fertilisants organiques (engrais vert, lisier de pore et fumier de bovin) sur la dégradation dans le sol de l'imazaméthabenz‐méthyle a été etudié au champ dans une culture de blé (Triticum aestivum) semé en novembre. L'herbicide a été appliqué en mars, 5 mois après l'incorporation des fertilisants. La demi‐vie de rimazaméthabenz‐méthyle dans le sol était 35, 55, 66 et 85 jours, respectivement dans les témoins et dans les parcelles ayant reçu l'engrais vert, le lisier de porc et le fumier de bovin. Dans les mêmes parcelles, la demi‐vie de la somme de l'imazaméthabenz‐méthyle et de son métabolite acide herbicide étaient respectivement 61, 98, 127 et 172 jours. Les fertilisants organiques ac‐croissaient done la persistance dans le sol de rimazaméthabenz‐méthyle et de son métabolite acide, c'est à dire le produit issu de l'hydrolyse de sa fonction méthylester. A la fin de la période culturale, les résidus de ces deux composés étaient faibles dans toutes les parcelles. La dégra‐dation dans le sol de l'imazaméthabenz‐méthyle a été aussi étudiée dans la betterave à sucre (Beta vulgaris) implantée comme culture de remplacement en avril dans un sol traité en novembre de 1'année précédente (cette situation peut se ren‐contreren casde retournement d'un blé d'hiver). La vitesse de dégradation de l'imazaméthabenz‐méthyle dans la culture de betterave à sucre était environ moitié moindre que chez le blé de printemps. Biodegradation von Imazamethabenz‐methyl und seinem sauren Metaboliten im Boden in Weizen und Zuckerrübe als Ersatzkultur Die Wirkung von 3 organischen Düngern (Gründüngung, Schweinegülle und Stallmist) auf die Abbaurate von Imazamethabenz‐methyl unter Feldbedingungen wurde in im November gesätem Weizen (Triticum aestivum) untersucht. Das Herbizid wurde im Mai ausgebracht, 5 Monate nach der Einarbeitung der Dünger. Die ‘Halbwertszeit’ für den Abbau des Herbizids im Boden war in der Vergleichsparzelle 35 Tage und in den organisch gedüngten Parzellen 55,66 bzw. 85 Tage. Für das Herbizid und seinen sauren Metaboliten zusammen lagen die ‘Halbwertszeiten’ in denselben Parzellen bei 61, 98, 127 bzw. 172 Tagen. Demnach verlängerten die organischen Dünger die Persistenz des Herbizids und seines Metaboliten (Hydrolyseprodukt der Methylesterfunktion) im Boden. Gegen Ende der Vegetationsperiode gingen die Rückstände der beiden Stoffe in allen Parzellen zurück. Det Abbau wurde auch auf Flächen untersucht, die nach einer Behandlung im November des Vorjahres mit Zuckerrübe (Beta vulgaris) bestellt waren (so als ob sie nach einem Ausfall der Weizenkultur eingesetzt würde). Die Abbaurate in dieser Ersatzkultur war etwa halb so hoch wie nach einer gleichen Behandlung in Sommerweizen.

Effect of sowing date and seeding rate on yield and yield components of irrigated canola (Brassica napus L.) grown on a red-brown earth in south-eastern Australia

Response of canola (Brassica napus) to factorial combinations of five sowing dates and seeding rates was investigated from 1987 to 1989. The experiments were conducted on red-brown earths in the Goulburn-Murray Irrigation Region of south-eastern Australia. Crops were sown at monthly intervals beginning in April each year. In 1987, seeding rates were 4.6, 7.0 and 14 kg ha-1, but in 1988 and 1989 the lowest rate was eliminated. The cultivar Marnoo was used each year and Eureka was included in 1989. There was no difference between yields of seed and oil for crops sown in April and May, but yields of seed and oil declined when sowing date was delayed beyond May. Oil contents were greater than 45% for the April, May and June sowings in 1988 and 1989. In contrast, seeding rates had no effect on yields of seed and oil. Marnoo produced a maximum seed yield of 398 g m-2 from the May sowing in 1987, and a minimum seed yield of 172 g m-2 from the September sowing in 1988. In 1989, Eureka out-yielded Marnoo in all but the August sowing. Eureka produced a maximum seed yield of 483 g m-2 from the April sowing and its lowest seed yield of 315 g m-2 from the August sowing. The number of pods per m2 was the major factor responsible for the significant changes in yield in all experiments. Seed yield was also strongly correlated (P < 0.01) with biomass, and to a lesser degree, with individual seed weight in all comparisons with the exception of Marnoo in 1989.

Use of linear models to predict the date of flowering in cultivars of subterranean clover (Trifolium subterraneum L.)

Time to flowering (f) of eight phenologically diverse subterranean clover ( Trifolium subterraneum) cultivars was measured on nine sequential outdoor sowings in one season at Launceston, Tasmania, and one sowing date and four seasons in Perth, Western Australia. Linear models were then used to relate the rate of progress towards flowering (l/f) to mean temperature and mean photoperiod prevailing between sowing and flowering. The models accounted for most (70-97%) of the variation observed in time to flowering within cultivars, consistent with all of these cultivars being quantitative long day plants and photoperiodic effects being modulated by temperature. Model parameter estimates varied between cultivars suggesting genotypic variation for sensitivity to both photoperiod and temperature. The models and respective parameter estimates were subsequently used to predict flowering behaviour of the same eight cultivars in seven sequential sowings at Katanning, Western Australia. Across all 56 cultivarxsowing combinations at Katanning, there was a close (1:1) agreement between observed times to flowering and those predicted, with the models accounting for most of the observed variation. The models were least effective where times to flowering were longest, viz. for April sowings of the latest-flowering cultivars, where flowering tended to occur later than predicted. The potential utility of the approach is discussed in relation to cultivar improvement.

Environmental control of lentil (Lens culinaris) crop development

SUMMARYThe lentil (Lens culinaris Medik.) cultivars Titore and Olympic were sown at Canterbury, New Zealand, on eight dates, from April to November in 1984 and in May and August in 1985. Of the four important physiological growth stages (sowing to emergence (S–E), emergence to flowering (E–F), flowering to physiological maturity (F–Pm) and physiological maturity to harvest (Pm–H)), the duration of all except E–F depended upon accumulated thermal time above 2 °C. The mean accumulated thermal times for E–F, F–Pm, Pm–H were 116, 565 and 293 °C days, respectively. Stage E–F required from 1165 °C days for an April sowing to 509 °C days for a November sowing. There was a highly significant positive relationship (r2 = 0·99) between the rate of development during E–F and mean temperature. Photoperiod also affected development rate.Neither of the two cultivars studied had a vernalization requirement for the induction of flowering. In both years, the development rate during E–F was highly dependent upon photoperiod-corrected temperature. The relationships presented show that development of lentil crops in Canterbury can be accurately predicted using accumulated temperature and photoperiod-corrected temperature.

The relationship between sowing date, infestation and damage by the maize stalk borer,Busseola fusca(Noctuidae), on maize in Awassa, Ethiopia

Abstract The relationship between sowing date and the maize stalk borer, Busseola fusca (Fuller) in terms of infestation rate, and crop damage was studied using ten successive sowing dates between April and July in 1985 and 1986. Different degrees of infestation by B. fusca were recorded from all sowing dates. Early sowing in April and the early part of May had significantly lower infestations of first generation larvae. Levels of infestation by second generation larvae were significantly higher on late sowing dates. High infestation by second generation larvae appeared to be connected with the high biotic potential of the moths of the first, non‐diapause generation. Second generation larvae caused crop loss ranging from 22–5 to 100% while it was only 0–22.6% due to the first generation. In conclusion, delay of sowing later than April may result in serious crop yield loss due to the second generation larvae of B. fusca in Awassa.

The relation between time of sowing of cereals and cereal cyst nematode (Heterodera avenae Woll.)

Many juveniles of Heterodera avenae Woll. were hatchable in April but hatching was inhibited by lack of water. Number of knots (infestations) per susceptible wheat plant in 1981 increased from less than 40 at the initial sowing in mid-May to a maximum of almost 80 in mid June sowings; in 1982, the maximum (80 knots/plant) was recorded at the initial sowing in late April. Loss in yield of grain of wheat and barley was minimal in crops sown in mid-May but rapidly increased to a maximum in crops sown in late May/early June, the optimum time of sowing for yield. This maximum loss changed little in crops sown up till early August and varied with the tolerance of the cultivar from 520 to 880 kg/ha. Early or late sowings reduced potential yield. Females with eggs first appeared on the roots 90 days (late July) after sowing, indicating that fallows to prevent reproduction of the nematode should begin in early August. Maximum numbers of females (16lplant) occurred in sowings at the optimum time for yield (late May/early June) and decreased in later sowings. Resistance in the host reduced numbers of females but applications of ethylene dibromide rarely did.

Seasonal occurrence of sorghum earhead bug,Calocoris angustatusLethierry (Hemiptera: Miridae) in southern India

Abstract The seasonal occurrence of the earhead bug Calocoris angustatus Leth. (Hemiptera: Miridae) in main and ratoon crops of two sorghum hybrids was studied in field experiments with fortnightly sowings. During April to June, 1984, early April sowings were severely infested and early June sowings had less infestation. Hybrid CSH 5 harboured more bug population than the other. A ratoon crop had a lower population than the main crop. In July to October, 1984, the crop sown in the first fortnight of September had the lowest population of 18 bugs per ten panicles and a higher population of 142–159 bugs in July sown crops. The main crop had a higher population in all the sowings with an average of 116 bugs per ten panicles whereas the ratoons of September and October had no infestation, a mean of 7 bugs per ten panicles. A third experiment sown during January to March 1985 differed from the others by having a lower population in the main crop (22 bugs) than in ratoon (72 bugs/10 panicles). In the main crop, the January sown crop had no population and crops sown in February and March were little infested, whereas ratoon crops had a higher population than the main crop in all sowings. In general, crops sown in February and March first fortnight, had a higher population. In all the sowings, of the four stages of observation, pre‐flowering, milky, dough and maturity stages, the dough stage had the maximum population of bugs except in crops sown during February and March 1985, where the milky stage had the highest population. Cultivar CSH 5 was always more attacked than K‐Tall.

The effects of grazing on components of grain yield in winter barley

Abstract A paddock-scale experiment was conducted over two seasons to determine whether winter barley will fit adequately into a fanning system that requires both feed and grain, and to investigate how grazing affects the grain yield components. The 6-row ‘Illia’ and 2-row ‘Priver’ cultivars produced 1.3–2 t/ha of DM by mid August when sown in April. Grazing to ground level in August reduced grain yields by about 10%, by reducing the ear population, despite the fact that mainstem apices were below soil level at thetime of grazing. Combine harvested grain yields ranged from 2.3 to 3.6 t/ha in seasons with below average rainfall.

The contribution of forage oats to annual feed production when grown after maize in a double cropping system

Abstract The cool season forage production of Florida oats (FO) was measured in a series of replicated small plot trials at the Ruakura Agriculture Centre over five successive seasons. The oats were grown as part of a double cropping system using maize as the complementary warm season crop. Combined annual forage maize/oats yields averaged 26 t dry matter (DM)/ha. Experiments in 1978 and 1979 showed that forage production of the earlier maturing FO was higher than that of New Zealand-bred oat and wheat cultivars (11–13 t DM/ha v. 9–11 t DM/ha) when sown in April and cut in early October (‘ensiling’ yield). Subsequent experiments from 1980 to 1982 measured the yield response of FO to three rates of nitrogen (N) fertiliser (O, 35 and 70 kg N/ha) applied during tillering, following direct drilling into maize stubble. ‘Ensiling’ yields were high (9–13 t DM/ha) but yield responses to N fertiliser were small except in 1981 when June and July were warmer than average. FO was capable of consistently high yields when grown between successive maize crops. Tolerance to Barley Yellow Dwarf Virus probably contributed to the high yield potential of FO. The annual yield from the double cropping system was restricted by summer moisture stress affecting maize yields and severe frosts affecting winter cereal yields. Despite the high production level from the double cropping system, present costs of its implementation in dairy systems are prohibitive.

Effect of time of sowing on grain yield, and nutrient uptake of wheats with contrasting phenology

Four wheat genotypes with varying vernalisation and daylength requirements were sown in the field on 5 occasions between early April and late June at Wagga Wagga and Temora, New South Wales, in 1974 and 1975. The period between sowing and heading decreased from 1068-1 324 degree-days (base temperature = 4�C) for crops sown in April to 660-841 degree-days for crops sown in late May. The genotype with the largest vernalisation response in this study (WW33G) produced the highest yields when crops were sown in early April. The cultivar Oxley, which has a small vernalisation response, produced the highest yields at almost all other sowing times. Shoot nitrogen (N) and phosphorus (P) uptake did not vary consistently in relation to the time of sowing. Grain protein concentration was higher at 3 of 4 sites with early sowing and grain P concentration was always significantly higher with early sowing dates. Higher concentrations of P were associated with higher concentrations of phytate. The concentrations of N and P were negatively correlated with yield and harvest index.

Lucerne seedling growth and first year productivity in south-eastern Australia as influenced by sowing date in autumn and early winter

A field experiment at Tatura, Vic., compared lucerne (Medicago sativa L.) seedling growth and first year productivity of 2 lucerne cultivars (cv. CUF101 and Dekalb 167) sown at monthly intervals from early autumn (March) to early winter (June). At the first hay cut in October, both delayed autumn sowing and the increased winter dormancy between cultivars resulted in significantly lower seedling DM and crop height. Total DM yield from 5 hay cuts during the first cutting season declined as sowing date was delayed. Yields were 18.5, 16.5, 14.5 and 13.1 t ha-1 for the March, April, May and June sowings, respectively. However, no differences in total yield occurred between cultivars despite better early growth of CUF101. During the first 20 weeks from each sowing, significant interactions occurred for seedling DM and crop height between sowing date and cultivar (P=0.05). At 20 weeks of age, seedling DM of the March sown CUF101 was significantly greater than for all other sowings at the same age. At 4 weeks, seedling DM of the June sowings were significantly lower than all others. However, at 20 weeks, seedling DM and crop height of the June sowings were significantly higher than for the April and May sowings. Seedlings of the May sowings remained small for the longest period. The greatest relative differences in seedling DM and crop height occurred at about 10 weeks after sowing where the March sown CUF101 and Dekalb 167 were 29 and 4 1 times greater than the May sown CUF101 and Dekalb 167 respectively. The comparison of seedling DM of the autumn sowings with spring (Sept. and Oct.) sown semi-winter-dormant lucerne (cv. Validor), showed that at 12 weeks of seedling age, seedling DM of the spring sowings was more than double that of the March sown Dekalb 167.