Normal Planting Dates Research Articles

Yield and Germinability of Seed from Irrigated and Nonirrigated Early‐ and Late‐Planted MG IV and V Soybean

Drought stress in the midsouthern USA reduces yield of soybean [Glycine max (L.) Merr.] planted in May and June and sometimes affects germination of harvested seed. Irrigation often increases yield, and may also increase seed germinability. Field experiments were conducted on Sharkey clay (Vertic Haplaquept, very‐fine, montmorillonitic, termic) in 1992, 1993, and 1994 at Stoneville, MS. The objective was to determine the effects of earlier‐than‐normal (April) and normal (May) planting dates on yield and germinability of harvested seed of Maturity Group (MG) IV and V soybean cultivars grown in nonirrigated (NI) and furrow‐irrigated (I) environs. In 1992, germination of seed of all cultivars harvested from the NI (14–73%) and I (36–77%) 15 April plantings was lower than that of seed harvested from the 27 May plantings. In 1993 and 1994, germination of all harvested seed averaged more than 90%. Without irrigation, seed yield from the April plantings exceeded that from the May plantings every year. The difference was greatest in 1992 (3170 vs. 2190 kg ha−1) and least in 1993 (1432 vs 1295 kg ha−1). In 1992, the 4195 kg ha−1 average yield with irrigation from the 15 April planting exceeded the 2979 kg ha−1 average yield from the 27 May planting. In 1994, yield of all irrigated cultivars in the 21 April planting equalled or exceeded the yield of the same cultivars planted on 13 May. Yields of MG V cultivars were equal to or greater than those of MG IV cultivars in both I and NI plantings in all years. These results demonstrate that April vs. normal May plantings of both MG IV and V cultivars can increase yields when grown with and without irrigation in the midsouthern USA.

Cultivar and planting date effects on soybean root growth

To avoid late summer drought, soybean [Gylcine max (L) Merrill] producers in many southern and border states of the USA modify their cropping systems. Options include use of unadapted cultivars and changing planting dates. Because root function is important to plant health and yield, this study was conducted to determine if planting date and soybean cultivar affect root growth and distribution. Seeds of one cultivar from each of four maturity groups (MG III, IV, V, and VI) were sown in mid-April, mid-May, and mid-June in 1992 and 1993 on a Tiptonville silt loam near Portageville, MO. Root observations were performed 30 and 60 days after emergence (DAE) using a minirhizotron system. Cultivars differed for root length density (RLD) only in the 15 to 28 cm depth in 1992 and in the 15 to 28 cm and 29 to 42 cm depths in 1993, but differences were not related to maturity classification of cultivar. Average RLD was 1.02 cm−3 for MG III and IV cultivars and 1.21 cm cm−3 for MG V and VI cultivars. Average RLD for the mid-June planting date was 1.65 cm cm−3 but only 0.73 cm cm−3 for the mid-April planting date. An increase in RLD between 30 and 60 DAE occurred at all soil depths. For both years, MG V and VI cultivars produced higher yields than the MG III cultivars. Earlier than normal planting dates inhibited early root growth, but did not reduce yield. Cultivars differed only slightly for the rooting characteristics measured in this study. These rooting characteristics may not be important criteria for cultivar selection.

Wheat Planting Date Effects on Soil Water Extraction and Grain Yield

AbstractDue to a wide range of irrigated and dryland production systems and highly variable weather, planting date of winter wheat (Triticum aestivum L.) grown in the Southern High Plains varies from August to November. A 2‐yr field study was conducted at Bushland, TX, to evaluate planting date effects on soil water extraction and grain yield. ‘TAM 107’ wheat was planted in late August to simulate a grazed production system, early October to represent an optimum date for grain production, and early November on preirrigated Pullman clay loam soil (fine mixed thermic Torrertic Paleustoll) and grown to maturity without further irrigation. Gravimetric soil water content to 3.6 m depth was determined at the beginning and end of winter dormancy and at anthesis. Water extraction prior to winter dormancy occurred to a depth of 1.8, 0.9, and 0.15 m for the early, normal, and late planting dates, respectively. Depth of water extraction at anthesis was 2.4, 2.4, and 1.2 m for the three dates. The fraction of total preanthesis soil water extraction that occurred during a critical 60‐d period immediately prior to anthesis was 0.22, 0.59, and 0.91 for the early to late planting dates, respectively. Planting in August greatly increased depth and amount of soil water extraction prior to winter dormancy; however, water deficits in the spring contributed to low head density and grain yield. Wheat planted in early October extracted as much soil water as the August planting by anthesis and produced high grain yield. Wheat planted in early November rooted only one‐half as deep, extracted two‐thirds as much water, and yielded two‐thirds as much grain as the October planting date. In conclusion, planting in August as compared with October did not increase soil water extraction at anthesis and grain yield was reduced because the period of major soil water extraction was shifted from spring to fall. Planting in November reduced grain yield because of insufficient rooting to fully extract soil water from below 1.2 m.

Relationship of Insect Damage and Other Factors to the Incidence of Speckback, a Site-Specific Lesion on Kernels of Milled Rice

Speckback, a small imperfection that occurs on the dorsal surface (the surface opposite the germ) of kernels of rice (Oryza sativa L.), is characterized by a variety of lesions, not all of which are discernible by the unaided eye and, therefore, are unlikely to be detected by inspectors in industry. Speckback has been known for years but was so rare and inconspicuous that it was not considered a problem. A sudden, dramatic increase in the incidence of speckback coincided with the release of the high-yielding, semidwarf, long-grain cultivars Lemont and Gulfmont. The superficial resemblance to peck, damage associated with the rice stink bug, Oebalus pugnax (F.), fostered suspicion that insects caused speckback. This imperfection, far more abundant in ‘Lemont’ and ‘Gulfmont’ than in other cultivars, was unaffected by chemical control of insects in commercial fields or test plots, by confining heavy infestations of insects with piercing-sucking mouthparts on rice panicles, by deliberate exclusion of all insects, or by stress (sheath blight) induced by the disease. Excessive or Iluctuating levels of irrigation water increased the incidence of speck back somewhat but was not the sole determining factor. Regardless of insect infestation or control, speck back was 3.8 times more abundant in ratoon-crop and 5.9 times more abundant in late-planted rice than in main-crop rice seeded on a normal planting date. There was no evidence that speck back was caused by or associated with insects.

Plastic mulch increases cotton yield, reduces need for preseason irrigation

Preseason irrigation of cotton has been identified as the single largest contributor to the drainage problem in the central San Joaquin Valley. By applying plastic mulch at earlier than normal planting dates, we conserved soil moisture that would have normally been lost to the atmosphere. The mulch also raised soil temperatures, resulting in rapid germination and early plant growth. Yields of Pima S-6 and Acala SJ-2 were 39% and 8% higher than nonmulched plots, respectively. Net profit increased by about $450 per acre for Pima because it attracted a higher price.

THE EFFECT OF ROW COVERS ON THE YIELD OF THREE TOMATO CULTIVARS

Three tomato varieties were evaluated for early and total yield using row covers. Tomatoes were planted three weeks earlier than the normal planting date and row cover treatments included; 1) slitted, clear polyethylene 2) floating, spunbonded, polypropylene and 3) bare, no row cover. `Pilgrim', `Celebrity' and' Mountain Pride' were selected as early, mid-season and late varieties, respectively. Row covers were removed after three weeks at which time a second planting was made, representing the normal planting time. Slitted, clear, polyethylene row covers significantly increased early yields in all varieties as compared to the bare treatment. In addition, clear row covers resulted in higher early yields in `Pilgrim' and `Mountain Pride' than floating row covers. Despite row covers over `Celebrity' and `Mountain Pride', early yields were still not as great as the `Pilgrim' cultivar without any row cover.

Narrow‐Row Seed‐Yield Enhancement in Determinate Soybean

AbstractAlthough many studies have been conducted to determine the effect of narrow vs. wide rows on determinate soybean [Glycine max (L) Merr.] yield, little information is available explaining why these yield responses occur. This research was conducted to determine the roles of reproductive partitioning, light interception duration (LID), and total dry matter duration (TDMD) between emergence to R5 (E‐R5) and R5 to R8 on narrow‐row seed‐yield enhancement. Field studies were conducted using normal and late planting dates, two commercial soybean cultivars, and 100‐ (wide) and 50‐cm (narrow) row spacings during 1987 and 1988 at Baton Rouge, LA on a Mhoon silty clay (fine‐silty, mixed, nonacid, thermic Typic Fluvaquent) soil, Significant narrow‐row seed‐yield enhancement occurred from both planting dates, but the increases were much larger at the late date. In the normal planting, seed yield was strongly correlated with LID (R5‐R7) (r2 = 0.77, P = 0.001) and TDMD(R5‐R8) (r2 = 0.86, P = 0.001), but not LID(E‐R5) or TDMD(E‐R5). In the normal planting, significant narrow‐row seed‐yield enhancement occurred only in cases in which narrow rows achieved 95% light interception before pod filling, but wide rows did not. In contrast, seed yield in the late planting was highly correlated to LID(E to R5) (r2 = 0.85, P = 0.001) and TDMD(E‐R5) (r2 = 0.81, P = 0.001), as well as LID(R5‐R7) (r2 = 0.98, P = 0.001) and TDMD(R5‐R8) (r2 = 0.94, P = 0.001). Although narrow‐row yield enhancement in the late planting was greatest when LID and TDMD were stimulated both before and after R5, significant yield increases in narrow versus wide rows occurred even in cases in which LID R5 to R7 differences were too small to affect TDMD(R5‐R8). In conclusion, narrow‐row seed‐yield enhancement of late plantings was influenced by increased LID and TDMD throughout the season, whereas only LID and TDMD enhancement during pod filling of normal plantings affected narrow‐row seed‐yield increases.

Selection for Seedling Cold Tolerance in Grain Sorghum1

Improvement in cold tolerance for sorghum (Sorghum bicolor (L.) Moench] would allow expansion of this crop into cooler regions than the current production areas, as well as lessen stand reductions in cool soils currently in production. Experiments were conducted in 1981 and 1982 to evaluate effectiveness of selection for cold tolerance in sorghum. A genetically broad‐based, random‐mating grain sorghum population, Purdue Population 9 (PP9), was used as the source population for increasing seedling cold tolerance. Purdue Population 9 Cold Tolerant (PP9CT) was developed through a phenotypic recurrent selection procedure utilizing natural selection in early spring plantings. Progress from selection was evaluated in early spring plantings in 1981 and 1982. In 1981, the C0 to C3 generations of PP9CT and two check genotypes were evaluated in plots planted with 100 seeds in a randomized complete block design. In 1982, the C4 generation was also included. Results from the first year indicated that a 10.6% increase in cold emergence had been accomplished after three cycles of selection. Data from 1982 indicated a 14.9% increase in cold emergence after four cycles of selection. Regression analysis on the combined tests showed a linear increase of 2.8% cycle−1. Plant height, days to half bloom, seed color, and grain yield were evaluated in trials planted at normal planting dates to determine the correlated responses in PP9CT following selection for seedling cold tolerance. Plant height showed an irregular response, days to half bloom decreased by 0.55 days cycle−1, seed color increased by 0.13 color units cycle−1, and grain yield increased by 197.7 kg ha−1 cycle−1.

Correlated Changes in Agronomic Traits from S1‐line Recurrent Selection for Cold Tolerance in Two Maize Populations1

Cold tolerance is an aggregate trait important to dependable stand establishment in many environments. Selection for improved cold tolerant maize (Zea mays L.) germplasm, however, must not deter improvement of traits that are important later in the growing season. Correlated changes in agronomic traits due to five cycles of S1‐line recurrent selection for cold tolerance were evaluated in two maize populations. Correlated changes in means were expressed in terms of changes in allelic frequency due to pleiotropy or linkage and drift. Selection was associated with correlated genetic changes (2Δpα) grain yield [0.22 Mg ha‐1 cycle‐1 when averaged over both BS13(SCT) and BSSS2(SCT)], grain moisture (‐0.3% cycle‐1), early stand count (0.7 plants plot‐1 cycle‐1), and final stand (387.4 plants ha‐1 cycle‐1). Root lodging resistance was increased 2.5% cycle‐1 in BS13(SCT) and decreased 2.0% cycle‐1 in BSSS2(SCT). Stalk lodging resistance decreased 0.40% cycle‐1 in BS13(SCT). The increased frequencies of pleiotropic or linked genes controlling grain yield and grain moisture were expressed at both early and normal planting dates. The correlated genetic changes in early stand count, final stand, and root and stalk lodging resistance were influenced by date of planting. Genetic drift (2Δp2d) was significant for grain yield (‐0.23 Mg ha‐1 cycle‐1). Genetic drift overwhelmed the increase in allelic frequency due to selection for grain yield; hence, the populations per se were unchanged. The data suggesthat selection for cold tolerance with larger effective population sizes may result in correlated improvements in yield of the populations per se.

Winter legumes as a nitrogen source for no-tillage cotton

Winter legumes can serve dual purposes in no-tillage cropping systems. They can provide a no-tillage mulch, and supply a considerable quantity of N for thesummer crops. Cotton ( Gossypium hirsutum L.) was no-tillage planted into crimson clover ( Trifolium incarnatum L.), common vetch ( Vicia sativa L.), and fallowed soil for two years to determine the effects of winter legume mulches on growth, yield, and N fertilizer requirements. The legumes were allowed to mature and reseed prior to planting cotton. The winter legumes produced no measurable changes in soil organic matter, N, or bulk density, but water infiltration was more rapid in the legume plots than in the fallowed soil. In the fallow system, 34 kg ha −1 N fertilizer was required for near maximum yields. In the clover plots, yields without N fertilizer were higher than when N (34 and 68 kg ha −1) was applied. In the vetch plots, cotton yields were highest without N fertilizer the first year, but yields were increased with 34 kg ha −1 N the second year because of a poor vetch seed crop and a subsequently poor legume stand. In the clover plots, a 20–30% cotton seedling mortality occurred in one year, but this stand reduction apparently did not affect cotton yields. Winter legume mulches can provide the N needs for no-tillage cotton without causing an excessive and detrimental quantity of N in sandy soils naturally low in soil N (0.04%). Unless the reseeding legume systems are maintained for at least 3 years, the legumes do not, however, provide an economical N source for cotton when N fertilizer requirementsare low (34 kg ha −1 in this study). A possible disadvantage of the system for reseeding legumes is that cotton planting is delayed 4–6 weeks beyond the normal planting date, which can reduce yields in some years.

Características fisiológicas dos cultivares de soja, UFV-1 e IAC-7, no florescimento, em diferentes épocas de semeadura e sua relação com a produção

Estudou-se os efeitos antecipadas, normais e retardadas de semeadura, nas características fisiológicas no florescimento, dos cultivares de soja, UFV-I e IAC-7, de ciclos tardios de maturidade e sua relação coma produção final de sementes. As características avaliadas foram: altura da planta, número de nós frutíferos, índice de área foliar e peso da matéria seca de folhas. O trabalho foi conduzido em condições de campo, no município de Campinas, SP, em um Latossolo Roxo eutrófico, durante os anos agrícolas de 1979/80, sendo as datas de semeadura a cada vinte dias no primeiro ano, ã partir de 05/10, e no segundo ano, mensais, à partir de 17/09, sendo consideradas oito e sete épocas respectivamente a cada ano. A antecipação afetou os valores de todas as características avaliadas, sendo menores, comparativamente àqueles obtidos nas épocas normais, no cultivar UFV-I. Os valores obtidos pelo cultivar IAC-7 foram idênticos nas épocas antecipadas e normais. 0 retardamento da época de plantio diminuiu drasticamente os valores de todas as características estudadas, nos dois culti vares. Todas as características avaliadas no florescimento correlacionaram-se com a produção de sementes, nos dois anos de experimento. Na comparação entre cultivares, em cada época, verificou-se que as diferenças observadas entre os mesmos não corresponderam à diferenças na produção de sementes. Concluiu-se que as características fisiológicas no florescimento são adequadas para avaliação do potencial produtivo dos cultivares nas diferen tes épocas, mas não entre cultivares numa mesma época.

Corn Physiology in Short Season and Low Temperature Environments1

AbstractNorthern areas seeking to expand corn (Zea mays L.) production and thereby reduce feed costs for livestock require early plantings of short season hybrids with good seedling vigor. The association between physiological behavior of corn to low temperature and its field performance could be important in selecting hybrids adaptable to such areas.Twenty corn hybrids of commercial importance in New Hampshire which varied in maturity were planted 21 April and 19 May at the Univ. of New Hampshire Agronomy Research Station, Madhury, NH; nine selections from the above were also grown at three other locations in the state with widely differing growing conditions. The effect of controlled temperature on chloroplast structure and photosynthetic activity was also determined using the earliest and one of the latest maturing hybrids which differed in early development under field conditions.Low temperatures following the early planting of 21 April did not adversely affect stand density of hybrids; seedling growth of the two earliest maturing hybrids was superior to all other selections. At the normal planting date of 19 May seedling growth of the 20 hybrids was negatively correlated with their maturity rank; seedling growth was greatest in the earliest hybrids.Yield of total dry matter (TDM) at maturity was not related to seedling growth. In field studies in the southern and middle part of New Hampshire with a growing degree days (GDD) range of 1,100 to 1,300, TDM yields of the earliest corn hybrids were lower than yields of the later maturing corn. At the northern locations, with GDD < 1,100, yield of TDM was not significantly different among hybrids although % DM was higher in early maturing corn. A greater decline in photosynthesis and altered chloroplast ultrastructure in the leaves of a late‐maturing corn following exposure to controlled day/night temperatures of 15/10 C in the greenhouse was observed; no such changes occurred at 15/10 C either in the earliest hybrid, which had shown superior seedling performance under field conditions, or in either hybrid when grown at 10/15 C.

Combination Surface-Subsurface Drainage Systems for Humid Regions

Simulations were made for corn productuion over a period of 25 yrs using normal planting and harvesting dates for the various locations. The number of working days during the one-month period prior to seedbed preparation and SEW 3 0 values during the growing season were predicted for each year of simulation. These results showed that trafficability during the seedbed preparation period is heavily dependent on the factors controlling the rate of subsurface drainage: drain spacing, depth, and soil properties. Surface drainage had a relatively small effect on trafficability for the cases considered. SEW 3 0 values are dependent on both surface and subsurface drainage. In most cases several alternative combinations of surface and subsurface drainage can be used to satisfy a given SEW 3 0 limit. Drainage requirements for trafficability during the seedbed perparation periods were about the same for three locations.

Tobacco Budworm Field Evaluation of Microbial Control in Cotton Using Bacillus thuringiensis and a Nuclear Polyhedrosis Virus with a Feeding Adjuvant123

Field tests were conducted in 1978 at Phoenix, AZ, to evaluate a feeding adjuvant, the nuclear polyhedrosis virus (NPV) from the alfalfa looper, Autographa californica (Speyer), and the HD-l strain of Bacillus thuringiensis Berliner in controlling Heliothis virescens (F.) in cotton. When cotton that was planted on a normal planting date (Apr. 21) was treated with the virus + a feeding adjuvant or virus + B. thuringiensis + the adjuvant, the percentage of squares and bolls damaged by Heliothis and the number of larvae in the fruiting forms were reduced 38–50 compared to numbers in untreated cotton. However, this reduction did not affect the yield of seed cotton. When cotton, planted late (June 26) to maximize tobacco budworm damage, was treated on a 5-, to 7-day schedule, yields of seed cotton in untreated plots, plots treated with virus alone, plots treated with virus + adjuvant, and plots treated with virus + B. thuringiensis + adjuvant were 332, 774, 1066, and 1427 kg/ha, respectively. Treatment with the virus + B. thuringiensis + adjuvant resulted in the boll damage never exceeding 5% and square damage never over 10%. In another late-planted area, the percentage of squares damaged by Heliothis in untreated plots, plots treated with B. thuringiesis alone, and plots treated with B. thuringiensis + adjuvant was 44.5, 18.3, and 8.8, respectively. The yield of seed cotton was 32% greater in cotton treated with the B. thuringiensis + adjuvant compared to the yield in cotton treated with the bacterium alone. Of Heliothis eggs examined during the tests, 89–98% were H. virescens , and the remainder were H. zea (Boddie).

Straw Mulch Effects on Soil Temperatures and Sorghum Germination and Growth1

AbstractThe possibility that lower than normal temperatures in residue‐covered soils may affect crops has caused concern regarding the use of conservation tillage systems in some regions. To evaluate this possibility in the Southern Great Plains, soil temperatures were measured at a 10‐ cnl depth in field plots on which 0 (check), 1, 2, 4, m 12 metric tons/ha of wheat (Triticum aestivum L.) straw were applied on the surface. The soil was Pullman clay loam, a fine, mixed, thermic Torrertic Paleustoll (order Mollisol). Objectives were to determine the effects of mulch‐induced temperatures on grain sorghum [Sorghum bicolor (L.) Moench] planting dates, germination, emergence, and growth, and to obtain information concerning effects of mulch rates on soil temperatures at various seasons and under specified climatic conditions. Increasing mulch rates delayed the time that soil reached favorable temperatures for sorghum germination and growth. However, temperatures were near optimum before normal planting dates and, therefore, mulches did not affect sorghum germination and only slightly delated emergence. Since temperatures with high mulch rates rarely, if ever, reached the optimum for sorghum growth, plants on these plots grew slower early in the season than those on plots with low mulch rates. Later in the season, when soil water limited growth, plants on high mulch late plots grew more than on other plots because of higher water contents. Increased mulch rates decreased average soil temperature means, maximums, minimums, and standard deviations during all seasons of fallow front wheat harvest to sorghum planting. However, when temperature of bare soil approached or fell below 0 C, the temperature effect was reversed. The change in temperature for each metric tons/ha of mulch as compared with bare soil was greatest for the 1‐metric ton/ha rate and generally decreased as mulch rates increased.

Influence of Conservation‐Tillage Environments on Growth and Productivity of Corn1

AbstractResearch on growth responses of corn (Zea mays L.) to environmental conditions associated with conservation‐tillage systems has not been extensively conducted. Therefore, the objectives of this study were to evaluate effects of various tillage systems (fall moldboard plow, till‐plant, no‐till ridge with and without previous‐crop residue) and early planting on growth and productivity of several corn genotypes (including two heterogeneous breeding populations that were improved for cold tolerance by recurrent selection). The experiment was conducted for 2 years on a loam soil (Typic Hapludoll), and planting dates were 1 Apr. 1974, and 30 Apr. 1975. Conservation‐tillage systems were associated with lower midafternoon soil temperatures (at 5‐cm depth) during the early growing season and more variability in depth of seed placement. Also, seedling and juvenile plant growth, final plant densities, and grain yields were lower in conservation‐tillage systems. These differences were accentuated in the early planting environment of the 1974 experiment. With a relatively normal planting date and equal final plant densities (the not affected by tillage treatment. There was no interaction between tillage method and com genotype. Usually, genotypes with vigorous seedling and juvenile plant growth and high final plant stands produced highest grain yields in all tillage environments. In the central U.S. Corn Belt, therefore, optimum corn grain yields in conservation‐tillage environments will be obtained by the use of planters that assure uniform seed depth and genotypes that display vigorous plant growth and development.

Proso Millet Date of Planting and Tolerance to Atrazine

Proso millet (Panicum miliaceumL. ‘Turghai’, ‘M28’, and ‘Panhandle’) was planted at three or four dates from late April to late June in 1970, 1971, and 1972 on silt loam soil and in 1972 on sandy soil. A single spray application of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) at 2.24 kg/ha on half of each date plot was preemergence to the first date and preplanting to the last two or three dates of planting. Proso millet was not injured by atrazine. At each date, weed control was better on sprayed than on untreated plots. Foxtails (Setariaspp.) were the only weeds present after all plots on silt loam soil were sprayed postemergence with (2,4 dichlorophenoxy)acetic acid (2,4-D). Millet planted early produced higher yields than millet sown at normal planting dates if foxtail competition was not serious. Use of selective herbicides and spring planting offer a potential major gain in the profitability of millet production in areas where annual weed problems now relegate millet to summer planting.