Summer Sowing Research Articles

봄과 가을 파종시 귀리 품종별 생육, 수량 및 사료가치 비교

귀리는 단기 다수성 작물로서 잎의 비율이 높을 뿐만 아니라 가축의 기호성도 양호하며 다른 총체맥류에 비하여 파종시기의 선택폭이 넓다. 따라서 본 시험은 내한성이 강하여 중부 지방에서도 월동이 가능한 귀리 3품종과 옥수수 뒷그루 재배에 알맞은 3품종에 대하여 10월 중순 가을 파종과 3월 상순 봄 파종시 생육, 수량 및 사료가치를 비교하고자 실시하였다. 출수기는 봄 파종시 가을 파종에 비하여 평균 12일 늦었고, 품종간에는 약 8일의 차이가 있었다. 봄 파종은 가을 파종에 비하여 이삭과 잎의 비율이 감소하고 줄기가 차지하는 비율이 증가되는 경향이었다. 품종별로는 동한귀리가 다른 품종에 비하여 이삭의 비율이 높고 줄기의 비율이 낮은 경향이었다. ADF 함량은 봄파종에서 높았고, NDF 함량과 가소화 건물 함량은 가을파종에서 높았다. 가소화 건물함량은 가을 파종시 동한귀리와 스완에서, 봄 파종에서는 삼한귀리가 높았다. 삼한, 동한, 조한귀리 3품종의 생초수량이 가을 파종이 봄 파종에 비하여 높았으나 건물수량은 비슷한 경향이었다. 스완, 다크호스, 하이스피드는 봄 파종이 가을 파종에 비하여 생초수량 및 건물수량이 월등히 높았다. 품종별로는 가을 파종과 봄 파종 모두 동한귀리가 건물수량과 가소화 건물수량이 높았는데, 이는 상대적으로 많은 이삭수의 확보와 이삭이 차지하는 비율이 높았기 때문이었다. Oats are an important crop for forage production with good palatability of livestock. Compared with other winter cereals crops for forage, oats may be widely sowing, autumn (October), spring (early of March) and summer (late of August). The objectives of this study were to compare the effects of sowing dates and varieties on the growth, forage yield and feed quality. Oat were sown in 14 October and 10 March, and harvested 20 days after heading in middle region of Korea. Varieties used were the 3 winter oat cultivars with cold tolerant and 3 cultivars for summer sowing. Heading was delayed about 12 days in spring sowing than in autumn sowing and the difference among varieties was 8 days. The rate of spike and leaf above aerial parts reduced and the rate of culm increased in spring sowing than in autumn. The variety 'Donghan' was higher the rate of spike and lower the rate of culm than that of other varieties. In spring sowing than in autumn, acid detergent fiber (ADF) content was higher, and neutral detergent fiber (NDF) and digestible dry matter (DDM) content was lower. In DDM content surveyed on 20 days after heading, 'Donghan' was higher in autumn sowing and 'Samhan' in spring sowing than that of other varieties. The oat variety 'Samhan', 'Donghan' and 'Chohan' were higher fresh yield in autumn than in spring, but similar dry matter yield. The variety 'Swan', 'Darkhorse' and 'Hispeed' were higher fresh and dry matter yield in spring than in autumn. The variety 'Donghan' can supplement high quality forage production in middle region at October and March because of the high-tillering and rate of spike per aerial part.

Replicating Life Cycle of Early‐Maturing Species in the Timing of Restoration Seeding Improves Establishment and Community Diversity

Tallgrass prairie is among the most endangered ecosystems in North America. High‐diversity restorations protect remnant habitat and expand native communities. Excluding land acquisition, the most expensive step in restoration is procuring seed. Given this cost, managers want to maximize seedling establishment. Native species that flower and ripen early in the growing season are included in a diverse seeding mix but as a group they have not successfully established. For early‐maturing species, the practice of storing seeds in a cold room from harvest until sowing in the dormant season effectively eliminates exposure to the summer conditions seeds would naturally have in the wild. In this study, we compared the effect of summer sowing timing and winter sowing timing on establishment in field conditions. In August 2004 and December 2004, we broadcast a seed mix of seven early‐maturing species: Antennaria plantaginifolia (L.) Richardson. (Pussy toes), Arabis lyrata L. (Sand cress), Carex swanii (Fernald) Mack. (Downy green sedge), Hymenopappus scabiosaeus L'Hér. (Old plainsman), Lupinus perennis L. ssp. perennis var. occidentalis S. Watson. (Wild lupine), Phlox bifida Beck. (Sand phlox) and Hesperostipa spartea (Trin.) Barkworth. (Porcupine grass). We collected data on establishment and reproductive success at 12 time points from June 2005 until October 2008. Species established one growing season sooner when planted at the summer sowing time, and diversity in the summer sowing plots was higher after 4 years. Quicker establishment may have benefits such as providing early competition from weeds that may outweigh additional effort required to ensure timely planting.

ORIGINAL ARTICLE: Effects of variety, sowing season and maturity stage on ruminal phosphorus release from whole maize stover and its morphological fractions

An in situ degradation technique was used to investigate the effects of variety, season and maturity stage on ruminal Phosphorus (P) release from whole maize stover and morphological fractions from five varieties of maize (conventional maize, CM; sweet maize, SM; waxy maize, WM; high oil maize, HOM; and fodder maize, FM). Maize plants were harvested in 2005, 17 and 31 days after tasselling and manually separated into leaf blade, leaf sheath, stem and husk. Results showed that the values of rapidly released P fractions (a), slowly released P fractions (b), rate constant of P release for fraction b (c) and effective disappearance (ED) of P were significantly influenced by variety, sowing season and maturity stage (p < 0.05). The ED of P in whole maize stover among the varieties decreased in the following order: FM (89.8%) > HOM (87.9%) > CM (87.0%) > SM (86.9%) > WM (83.9%). Advanced maturity stage increased (p < 0.001) the a and ED values of P in the leaf blade and leaf sheath, but decreased (p < 0.001) these parameters in the husk. The a fraction and ED of P were higher (p < 0.001) for maize sown in spring than those sown in summer. Significant (p < 0.05) interactions among variety, sowing season and maturity stage were noted in the a and ED values of P. Effective disappearance of morphological fraction varied significantly (p < 0.001) and followed the order: stem (90.3%) > leaf sheath (88.2%) > leaf blade (85.2%) > husk (84.9%). In conclusion, most of P in maize stover could be released in the rumen. The potential pollution resulting from P excretion in faeces may be alleviated, when maize stover is largely used as the main forage source of ruminants.

Genetic Improvement of Wheat Growth Habit and Its Molecular Marker- Assisted Selection in Yellow and Huai River Reaches

The vernalizatioin gene in wheat cultivar Shimai 12 (Triticum aestivum L.) was investigated to find a more efficient way for the improvement of growth habit of wheat cultivars grown in Yellow and Huai River Reaches. In the F2:3 lines derived from the cross between Shimai 12 and Shijiazhuang 8 (a winter wheat cultivar), the ratio of the spring, segregating, and winter lines was in accordance to 1:2:1 based on chi-square test, showing that the spring growth habit of Shimai 12 was determined by single dominant gene, which was identified as Vrn-D1 by gene-specific markers. The Vrn-D1 gene-specific marker was further used to genotype the F2:3 lines, and the results were consistent with phenotyping, verifying the available utilization of the marker assisted selection for Vrn-D1 in breeding programs. Besides, summer sowing in high altitude and cool area proved to be a cost-saving and efficient method for wheat growth habit identification.

Exploiting genotypic variability from low-altitude Brazilian Savannah-adapted Chenopodium quinoa

Saponin-free quinoa genotypes were evaluated in summer and autumn–winter sowings, for phenotypic traits and yield stability. They were obtained by single plant-progeny selection from hybrids, as part of the breeding efforts in adapting the crop to the Brazilian Savannah environments. The soils (Ferralsols) were limed and fertilized prior to cultivation. The experiment was sown in two dates: 20th December 2006 (summer), and 30th April 2007 (autumn–winter), at 15°39′ and 16°14′ S latitude, 47°27′ and 47°44′ W longitude, with altitudes of 976 and 1,110 m, respectively. The mean temperature and rainfall for the summer sowing were 23.0°C and 723 mm. In autumn–winter, under controlled irrigation, the mean temperature was 2.9°C lower than in summer, when plants were exposed to water logging spells. The treatments consisted of fourteen selected genotypes and the varieties Kancolla, BRS Piabiru and Q4.5, used as controls. Comparisons were based on plant height, biomass and grain yield, harvest index (HI) and 1,000 seed weight. The experimental design was a complete randomized bloc, with three replications. Analysis of variance was performed for each sowing and jointly. Statistical differences for the environments were evident only for grain size and plant height. The performance of selected genotypes in each sowing date and in the joint analysis, allows saying that populations Q0779, Q0780 and Q0782 are potentially useful in the acquisition of stable genotypes for the Brazilian Savannahs.

Effects of water stress at different development stages on yield and water productivity of winter and summer safflower ( Carthamus tinctorius L.)

A field study was carried out to determine the effects of water stress imposed at different development stages on grain yield, seasonal evapotranspiration, crop–water relationships, yield response to water and water use efficiency of safflower ( Carthamus tinctorius L.) for winter and summer sowing. The field trials were conducted on a loam Entisol soil in Thrace Region in Turkey, using Dincer, the most popular safflower variety in the research area. A randomised complete block design with three replications was used. Three known growth stages of the plant were considered and a total of 8 (including rainfed) irrigation treatments were applied. The effect of irrigation or water stress at any stage of development on grain yield per hectare and 1000 kernel weight, was evaluated. Results of this study showed that safflower was significantly affected by water shortage in the soil profile due to omitted irrigation during the sensitive vegetative stage. The highest yield was observed in the fully irrigated control and was higher for winter sowing than for summer sowing. Evapotranspiration calculated for non-stressed production was 728 and 673 mm for winter and summer sowing, respectively. Safflower grain yield of the fully irrigated treatments was 4.05 and 3.74 t ha −1 for winter and summer season, respectively. The seasonal yield response factor was 0.97 and 0.81 for winter and summer sowing, respectively. The highest total water use efficiency was obtained in the treatment irrigated only at vegetative stage while the lowest value was observed when the crop was irrigated only at yield stage. As conclusions: (i) winter sowing is suggested; (ii) if deficit irrigation is to apply at only one or two stages, Y stage or Y and F stages should be omitted, respectively.

Relationships between earliness of head formation and developmental characteristics of cabbage (Brassica oleracea L.) in two different growing seasons, autumn and spring

We investigated and compared the relationships between the earliness of head formation and developmental characteristics of cabbage cultivars grown in spring (sown in early spring, harvested in early summer) and autumn (sown in summer, harvested in late autumn). In both seasons, earliness of head formation, namely the duration of the period to attain the target head weight from transplanting, was highly correlated with the leaf position at which head formation started (LPH): the lower the LPH value, the earlier head formation. This result suggests that a low LPH value is necessary for early-head-forming cultivars. However, the LPH value in some cultivars varied with the growing season, showing a significant genotype (G) × environment (E) interaction. To determine whether this G × E interaction might influence the use of LPH as a selection criterion, we analyzed the developmental pattern of the leaf shape. In cultivars with LPH values that largely differed between the two seasons, the leaves were longer up to a higher leaf position and widened later in the spring than in autumn, mainly because of delayed shortening of the petiole. We thus characterized the complex nature of early head-forming in spring, and suggested that LPH was a useful selection criterion for the development of early head-forming spring cultivars.

QTL Analysis of Popping Fold and the Consistency of QTLs Under Two Environments in Popcorn

Popping fold (PF) is the most important quality trait in popcorn. In this study, a total of 259 F 2:3 families, derived from the cross between a dent corn inbred Dan232 and a popcorn inbred N04, were evaluated for their popping folds in replicated experiments under two environments. Of 613 simple sequence repeat (SSR) primer pairs screened, 183 pairs were selected to construct a genetic linkage map with the genetic distance of 1 762.2 cM (centimorgan) and on average 9.63 cM every marker. Quantative trait loci (QTL) were identified, and their genetic effects were estimated using CIM (composite interval mapping) method. The interactions among QTLs detected were calculated using MIM (multiple interval mapping) method. In all, 22 QTLs were detected, and only 5 of them were common under two environments. Contribution to phenotypic variation of a single QTL varied from 3.07% to 12.84%, and total contributions of all QTLs under two environments were 66.46% and 51.90%, respectively. Three QTLs (qPF-6-1, qPF-8-1 and qPF-1-3) with more than 10% contributions were observed. The additive effects were larger than dominant effects for most QTLs. The amount of QTLs showing additive, partially dominant, dominant and over-dominant effects were 4, 5, 0, 2 in spring sowing and 2, 5, 2, 2 in summer sowing, respectively. There were only 2.60% pairs of QTLs or maker intervals expressing AA, DA or DD interactions.

Sowing seasons and drying methods during post-harvest influence the seed vigour of soybean (Glycine max (L.) Merr.)

Experiments were conducted to study the influence of sowing seasons and drying methods on the seed vigour of two spring soybean (Glycine max (L.) Merr.) cultivars. Two cultivars, ‘Huachun18’ and ‘Huachun 14’, were sown in three seasons viz., spring, summer and autumn and the harvested seeds were dried using three different methods. The results showed that soybean sown in spring had a higher number of branches per plant, pods per branch and seed weight, and consequently resulted in higher seed yields than that of soybean sown in autumn or summer seasons. Seeds sown in the autumn season had the lowest values of electrical conductivity during seed imbibitions, higher peroxidase (POD) activity in germinated seedlings and lower contamination by the seed-borne fungi on the MS medium, which indirectly improved the seed vigour, which was followed by summer sown seeds. Seeds sown during the spring season resulted in poor seed vigour. In addition, the effect of drying methods on the seed vigour was also clarified. Seeds that hung for four days before threshing and then air-dried had the poorest seed vigour which was determined by germination, electrical conductivity, POD activity and seed borne fungal growth. There was no difference in seed vigour between other methods, i.e. seeds threshed directly at harvest and then air-dried on a bamboo sifter or concrete floor. These results indicated that autumn sowing soybean and the drying method in which seeds were threshed directly at harvest and then air-dried on a bamboo sifter resulted in higher seed vigour.

Rendimento de sementes produzidas na sucessão soja – milho safrinha na região noroeste do Paraná

An work was carried out in the cropping season of 2001/02 with the purpose of evaluate the seed yield under the crop sucession of soybean and corn cultivated during the autumn-winter period, as well as to compare the seed production of early sowed soybean and late sowed corn with the sowing in the conventional dates for both cultures, in Maringa, State of Parana, Brazil. In this regard, an assay was conducted with three precocious soybean cultivars (BRS 183, CD 207 e M-SOY 6101) and three hybrids of corn (CD 304, OC 705 e CD 3121), in complete randomized blocks design, with four replications. Each assay was sowed at different dates. The early sowing date of soybean was in 10/20 and the delayed sowing date of corn was immediately after the harvest of the three soybean cultivars. The early and delayed sowing dates of the two cultures were compared with sowing at 10/15 and 11/15 for corn and soybean, respectively. The evaluated characteristics were seed yeld in kg ha, seed moisture content (wet basis) and a thousand seeds weight of soybean and corn. The obtained results allowed concluding that the early sowing date of soybean did not affect seed yield and thousand seeds weight of the three precocious soybean cultivars. The autumn-winter sowing date of corn reduced the yield of the three evaluated hybrids in comparison with the summer sowing date. A thousand seeds weight characteristic of the corn hybrids had significant reduction in the autumn-winter sowing date. Differences among corn hybrids to the seed yield potential were observed due to the delayed sowing date, however, the same behavior was not observed between the soybean cultivars. The autumn-winter sowing date of corn was not an adequate option of crop management considering the great reduction of seed yield in this period.

Root and shoot attributes of indigenous perennial accessions of the wild mungbean (Vigna radiata ssp. sublobata)

Root and shoot attributes of 12 indigenous perennial accessions of the wild mungbean (Vigna radiata ssp. sublobata) were evaluated in early and late summer sowings in the field in SE Queensland. All but one of the accessions were obtained from the Townsville–Charters Towers region of NE Queensland. In both sowings, the accessions developed thickened tap and lateral roots, the taproot thickening extending to a depth of 0.20–0.30 m below the soil surface, depending on accession. The thickened lateral roots emerged from the taproot within 0.10 m of the soil surface, and extended laterally up to 1.10 m, remaining close to the soil surface. Differences among the accessions in gross root morphology and phenology were relatively small. There were differences among the accessions in the production of seed, tuberised root, and recovered total plant biomass. Depending on accession and sowing date, the tuberised roots accounted for up to 31% of recovered plant biomass and among accessions, the root biomass was positively correlated with total plant biomass. In contrast, seed biomass represented only a small proportion of recovered plant biomass, up to a maximum of 14%, depending on accession and sowing date. Among accessions, the proportion of seed biomass tended to be negatively correlated with that of tuber biomass. The perennial trait appears to be unique to Australian accessions of wild mungbean obtained from coastal-subcoastal, speargrass-dominant woodlands of NE Queensland. Although the ecological significance of the trait remains conjectural, field observation indicates that it facilitates rapid plant re-growth following early summer rainfall, especially where dry-season fire has removed previous-season above-ground growth.

The establishment success of native versus non-native herbaceous seed mixes on a revegetated roadside in Central Texas

Revegetation is an essential component of roadside and building site construction and improvement. In the southern United States, non-native grass species are frequently included in revegetation seed mixes used by highway authorities. Non-native species are frequently selected for aggressive growth characteristics; however, these same traits also render them potentially invasive, and subsequently hazardous to adjacent plant communities. Although the use of pure native seed mixes has been rejected in the past due to perceived inferior establishment characteristics, there have been few comparative quantitative field studies that justify this belief. The establishment characteristics of three seed mixes—one containing non-native species and two with native grass and forb species only—were compared in a randomized-block design along a Texas roadside following spring and summer sowing. After 60 days following the spring sowing, the two native-only seed mixes demonstrated 180 and 560% ( F = 10.18; P < 0.0001) higher seed densities than the recommended native/non-native mix. The summer sowing results were similar with seedling densities 180 and 330% ( F = 9.20; P < 0.01) greater than the standard non-native seeding. Although an aggressive colonizer from vegetative tissue such as stolons and rhizomes, the non-native Bermudagrass ( Cynodon dactylon) had a lower than expected establishment rate thought to be due to high water demand during the first week following sowing. Given the invasive characteristics of this common component of many recommended revegetation seed mixes, these results call into question the widespread recommended use of Bermudagrass for such projects. Although gathered during 1 year only, these data indicate that examination of suites of early- and late-successional native species can provide a highly effective mix for revegetation projects. Furthermore, this reduces the potential for negative ecological consequences and provides added benefits associated with wholly native plant communities.

Scheduling of irrigation in snap bean (Phaseolus vulgaris var. nanus) using canopy temperature

The present paper evaluates the result of irrigation experiments carried out on snap beans sown in spring and summer and grown with and without irrigation. The experiments were run over the course of 12 years. In the average of 12 years, the yield was 2.8t ha-I for spring sown and 1.9 t ha-I in summer-sown plants without irrigation. The lowest level of profitable production, the 5.5t ha-I was reached twice in the case of spring sowing and only once in the case of summer sowing. Profitable yield production can be ensured only with regular irrigation and thus the yield may be increased by 4-5 times. In four of the twelve years we determined the canopy surface temperature of snap bean stands with and without irrigation. A Raynger II infrared remote thermometer determined the canopy surface temperature every day at 13.00 hours. The canopy temperature can well characterize the water supply of plant stands. This parameter may be used for describing the degree of drought and the water turnover of plant stands with different water supply. The positive values of foliage-air temperature differences (SDD) numerically express the degree of drought and the water supply of the crops. The results indicated that a 1 °C higher SDD value may cause 90-130 kg/ha yield loss.

Populações de plantas, adubação e calagem para o feijoeiro (cv. Iapar 81) em um Gleissolo de Ponta Grossa, Estado do Paraná

Aiming to study plant populations behavior and levels of fertilization and liming most adequate to the Iapar 81 bean crop, a field experiment was conducted in Ponta Grossa–PR, in the 2000/2001 summer sowing season. The experimental design was randomized blocks with four replicates and 4 x 4 factorial arrangement, involving four plant populations (100, 200, 300 and 400 thousand plants ha -1 ) and four fertilization and liming levels (0.0, 0.5, 1.0 and 1.5 doses, being 1,0 corresponding to IAPAR recommendation). The plant population increase reduced linearly the grain number per plant and pods number per plant; in spite of that, it caused an increase in grain yield up to 303 thousand plants ha -1 , causing reduction in higher populations. The increase of the fertilization and liming levels raised linearly plant height and the number of pods per plant, but it was not enough to raise grain yield, this parameter was limited by severe defoliation, caused by angular leaf spot and excess of rains in the final stages of the vegetative cycle

The Effect of Topdressing and Stock-neared Fertilization on Yield and Nitrogen Uptake in Summer Sowing Cabbage

The Effect of Topdressing and Stock-neared Fertilization on Yield and Nitrogen Uptake in Summer Sowing Cabbage

Evaluation and application of the OILCROP–SUN model for sunflower in southern Italy

Crop simulation models are potentially useful tools in agricultural decision-making. In Italy, few applications have been recorded, and those implemented have been mainly restricted to the estimation of crop water requirements in irrigated basins or the estimation of potential crop yields. In general, a model must be evaluated in a variety of conditions as a pre-requisite for its use. The OILCROP–SUN model was first parameterised and then validated, using independent data sets coming from three southern Italian environments in which sunflower was subjected to different irrigation schedules. The validation showed the model to be effective in simulating phenology, seed yield and seasonal evapotranspiration, whereas seed weight was rather poorly simulated. The model simulated the temporal changes in soil water content, leaf area index and total dry matter reasonably well. The model application consisted in comparing spring vs. summer sowing of sunflower in the three environments and in selecting the optimal threshold value of available soil water at which to start automatic irrigation. As for the sowing dates, the spring sowing showed a higher seed yield and net return than the summer sowing. With regard to the irrigation regimes, the highest seed yield was obtained with a soil water content within the 80–100% range of available soil water, while the highest economic return was reached using a threshold value of 40% of total soil water.

The Effect of Different Types of Fertilizer and Their Application Amount on the Change of Soil EC and the Growth of Summer Sowing Cabbage

The Effect of Different Types of Fertilizer and Their Application Amount on the Change of Soil EC and the Growth of Summer Sowing Cabbage

Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.)

Herbage yield of alfalfa (Medicago sativa L.) depends on forage management or environmental conditions that change C and N resource acquisition, and endogenous plants factors such as root organic reserves and number of active meristems. The aim of this work is to study the influence of two sowing dates in summer (12 July or 9 August), N fertilization (0 or 100 kg ha(-1)) and/or irrigation applied during the first year of alfalfa establishment on (i) the accumulation of N organic reserves (soluble proteins and more specifically vegetative storage protein) in taproots during autumn, (ii) the number of crown axillary meristems present at the end of winter and (iii) the dynamics of spring shoot growth. Delaying the sowing date for one month reduced root growth and root N storage, especially vegetative storage proteins (VSP) during autumn. Irrespective of sowing dates, N fertilization did not affect root biomass, number of crown buds, total root N, root soluble protein or VSP concentrations. By contrast, water deficiency during alfalfa establishment in the early summer reduced both root growth and N reserve accumulation. When spring growth resumed, there is a significant linear relationship between leaf area development and soluble protein and VSP concentrations in taproots, and also the number of crown buds. The results showed that an early sowing date and adequate water status during the summer allowed alfalfa plants to accumulate N reserves by increasing taproot mass and soluble protein concentrations, especially VSPs. This resulted in rapid shoot regrowth rates the following spring.

Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa ( Medicago sativa L.)

Herbage yield of alfalfa ( Medicago sativa L.) depends on forage management or environmental conditions that change C and N resource acquisition, and endogenous plants factors such as root organic reserves and number of active meristems. The aim of this work is to study the influence of two sowing dates in summer (12 July or 9 August), N fertilization (0 or 100 kg ha −1 ) and/or irrigation applied during the first year of alfalfa establishment on (i) the accumulation of N organic reserves (soluble proteins and more specifically vegetative storage protein) in taproots during autumn, (ii) the number of crown axillary meristems present at the end of winter and (iii) the dynamics of spring shoot growth. Delaying the sowing date for one month reduced root growth and root N storage, especially vegetative storage proteins (VSP) during autumn. Irrespective of sowing dates, N fertilization did not affect root biomass, number of crown buds, total root N, root soluble protein or VSP concentrations. By contrast, water deficiency during alfalfa establishment in the early summer reduced both root growth and N reserve accumulation. When spring growth resumed, there is a significant linear relationship between leaf area development and soluble protein and VSP concentrations in taproots, and also the number of crown buds. The results showed that an early sowing date and adequate water status during the summer allowed alfalfa plants to accumulate N reserves by increasing taproot mass and soluble protein concentrations, especially VSPs. This resulted in rapid shoot regrowth rates the following spring.

Efeitos do preparo do solo, plantio direto e de rotações de culturas sobre o rendimento e a economicidade do feijoeiro irrigado

O objetivo deste trabalho foi identificar os efeitos de sistemas de preparo do solo e de rotações de culturas sobre o rendimento de grãos e economicidade da cultura do feijoeiro (Phaseolus vulgaris L.) irrigado pelo sistema pivô central. O trabalho foi conduzido durante seis anos consecutivos, na Embrapa-Centro Nacional de Pesquisa de Arroz e Feijão, localizado no Município de Santo Antônio de Goiás, GO, em Latossolo Vermelho-Escuro, de textura argilosa. O experimento consistiu de um fatorial 4 x 6, em delineamento inteiramente casualizado, com parcelas subdivididas. Os sistemas de preparo do solo foram: P1 arado de aiveca (novembro-dezembro) alternado com grade aradora (maio-junho); P2 arado de aiveca contínuo; P3 grade aradora contínua; P4 plantio direto; e as rotações de culturas: R1 arroz-feijão; R2 milho-feijão; R3 soja-trigo, R4 soja-trigo-soja-feijão-arroz-feijão; R5 arroz consorciado com calopogônio-feijão; e R6 milho-feijão-milho-feijão-arroz -feijão. As rotações R1, R2, R3 e R5 foram anuais, e as R4 e R6, trienais. Neste trabalho analisaram-se somente as rotações que continham feijão. O arroz, o milho e a soja foram semeados em novembro-dezembro (verão), e o feijão e o trigo, em maio-junho (inverno). Houve efeito do preparo do solo e das rotações de cultura sobre o rendimento de grãos do feijoeiro. A cultura produziu mais quando se utilizou no preparo do solo a combinação de arado de aiveca, nos cultivos de verão, e grade aradora nos de inverno. Os rendimentos do feijoeiro foram maiores quando a cultura foi implantada bienalmente na mesma área, nas rotações com arroz/calopogônio e arroz, e menores, nas rotações com milho. O feijoeiro irrigado, com relação ao preparo do solo e rotações de culturas, foi economicamente viável, propiciando taxas de retorno que variaram de 67% a 97%.