Total Leaf Area Duration Research Articles

Optimization of irrigation period improves wheat yield by regulating source-sink relationship under water deficit

The optimization of irrigation scheduling presents an effective methodology for augmenting crop yields and enhancing water utilization efficiency. Nonetheless, a comprehensive understanding of the intricate mechanisms through which this strategy influences crop growth and yield formation is yet to be fully understood. In this study, a field experiment was conducted during the winter wheat cultivation period from 2018 to 2020 on two wheat cultivars: JM418, known for its drought tolerance, and SX828, known for its drought sensitivity. These treatments were subjected to four distinct irrigation schedules and two sowing stages. The timing of irrigation was specifically designed to coincide with the visibility of the 3rd, 4th, 5th, and 6th leaves for normal and postponed sowing. Our findings revealed that commencing irrigation at the stage when the 4th leaf becomes visible serves as an advantageous strategy for deficit irrigation. This approach significantly amplified winter wheat yield by 6.96–54.09 % and improved water use efficiency by 9.88–47.62 %. Quantitative analysis of source ability parameters demonstrated that postponed irrigation adversely affected the mean leaf area index (MLAI), total leaf area duration (TLAD), and biomass at maturity (BAM). Furthermore, an increase in mean net assimilation rate (MEAR) and harvest index (HI) was noted during the delayed irrigation phase when the 4th leaf was visible. The highest spike count per hectare was observed when irrigation was executed at the 4th leaf visibility stage, with an average increase of 13.98 %. Conversely, with a postponed irrigation schedule, the mean count of grain number per spike decreased by 2.47, while the 1000-grain weight saw an increase of 1.65 g. Higher sink capacity was obtained with irrigation when the 3rd and 4th leaves were visible. Despite this, the grain-leaf ratios when irrigated at the 4th, 5th, and 6th leaf visibility stages were significantly higher than those irrigated at the 3rd leaf visibility stage. In conclusion, our findings elucidate that the irrigation strategy coinciding with the 4th leaf visibility stage exhibits superior grain yield and water use efficiency (WUE) stability. This can be attributed to the enhanced harvest index, effective spike number per unit area, and biomass accumulation. Concurrently, the number of grains per panicle and the 1000-grain weight were relatively balanced. Our research offers novel insights into the mechanism of source-sink regulation in crops under deficit irrigation conditions and lays the groundwork for the development of precise and efficient irrigation strategies.

Maize Yields Performance in Strip Planting Patterns with Two Plant Densities

The Huang-Huai-Hai Plain is the most important maize production region in China. To further investigate the improvement of maize yield by changing the planting pattern combined with two plant densities in this region, field experiments involving four planting patterns (three-row strip, four-row strip, five-row strip and a conventional uniform row spacing pattern (the control) under two plant densities (67,500 and 82,500 plants/ha) were conducted in 2011 and 2012. Only the plant density, not the planting pattern, significantly influenced the leaf area index at R1 stage and the total leaf area duration. The radiation use efficiency and the above-ground biomass at R5 were both higher under the three strip planting patterns than under the control, but the differences were not statistically significant. The effects of the planting patterns on the grain yield were significant in both years and the yields were 16.7, 6.1 and 10.7%, respectively higher in 2011 and 17.2, 12.1 and 10.6%, respectively higher in 2012 under the three-, four- and five-row strip treatments, respectively, compared with the control. However, grain yield was affected by neither plant density nor the interaction between planting pattern and plant density. Therefore, optimal strip planting pattern could not be better estimated by considering plant density.

Modeling the impacts of irrigation treatments on potato growth and development

We analyze the effects of four irrigation treatments on the growth and development of potatoes (Solanum tuberosum L.) cv Agria, using a pivot irrigation system in the province of Albacete (Castilla-La Mancha, Spain), during 2011 and 2012. We find no significant differences between irrigation treatments regarding when the phenological phases are reached. The high day and night temperatures that occurred during the second season contributed to the lengthening of the agronomic cycle. We observed maximum values of leaf area index (LAI), total dry matter (TDM), crop growth rate (CGR), and relative growth rate (RGR) in the non-stress treatments (100% and 120% of crop water requirements). The highest values of total leaf area duration (LAD) were observed in the reference treatment (100% of crop water requirements) in both seasons, while the highest values of leaf area ratio (LAR) were observed when the crop reached full coverage of the soil. In the second season, the net assimilation rate (NAR) was more notably influenced by the water deficit treatments. A water application higher than 100% of crop water requirements did not influence crop growth and development. Therefore, deficit irrigation might be appropriate in areas where water is limited.

Establishment and two-year growth of a bio-energy plantation with fast-growing Populus trees in Flanders (Belgium): Effects of genotype and former land use

Abstract In April 2010, a large-scale Short Rotation Coppice (SRC) plantation was established with mainly poplar ( Populus spp.) on a former agricultural site (cropland and pasture) in Flanders. The 12 selected genotypes planted were assessed on establishment and production characteristics during the first two years of growth and were found highly productive, with a volume index ranging between 1.00 (±0.68) and 1.93 (±0.97) dm³ in growing season 1 (GS1) and between 2.75 (±1.70) and 11.91 (±6.33) dm³ in growing season 2 (GS2). Despite high survival rates of the cuttings after planting, competitive weeds and management operations increased tree mortality during the growing season from 3.4 % up to 18.2 % averaged over the entire plantation. Weed control therefore turned out to be the key factor in the establishment success. Only a minor influence of former land use was observed during GS1, which is explained by the non-limiting nutrient conditions on both former cropland and pasture, and which disappeared during GS2. These productive soils also explained the high growth rates, with an average tree height of 247 cm and 445 cm and stem diameter (at 22 cm height) of 25.21 mm and 40.73 mm after GS1 and GS2, respectively. Genotypic and parentage variations were found to be less pronounced during GS1, and increased during GS2 as expected. The maximum leaf area index and total leaf area duration were shown to be good indicators of production and growth performance. The results of this paper confirm the high potential of SRC with poplar on agricultural land for bio-energy purposes.

Effect of Plant Growth Substances on Morphological and Anatomical Structure of Leaf and Photosynthetic Characteristics in Soybean

Many soybean [Glycine max(L.) Merr.] morphological and physiological regulations responding to plant growth substances have been reported.Related researches showed that plant growth substances could effectively control lodging,increase leaf area index,promote photosynthesis,reduce productive abscission and improve yield and quality in soybean production.Plant growth substances through adjusting inner hormone control soybean's whole process of growth and development,at the same time possibly affect the structure of soybean organs,including root,stem,leaf,and productive organs,on which there are a little report.Microtechnique and ultramicrotechnique have triumphantly applied in the researches on the changes of fibre texture and ultrastructure in plant caused by nutrient elements and environment factors,which provides availibility to research the effects of plant growth substances on the structure of soybean organs.The present study was carried out in an attempt to compare anatomi-cal structure and photosynthetic characteristics of cultivar Kennong 4,treated with three plant growth substances in the field of experiments on trail farm of Heilongjiang August-First Land Reclamation University in 2006.The selected secure plant growth substances Diethyl anlinoethyl(DTA),Ckolirte chloride(Cc),and SOD simulation material(SODM),were applied by leaf-spraying at the beginning of blossom stage(R1).30 days later,at the beginning seed stage(R5),the functional leaves were sampled to compare fibre texture and ultrastructure by microtechnique and ultramicrotechnique.Photosynthetic characteristics,such as leaf index,photosynthetic pigment content,photosynthetic potential and photosynthetic rate,were measured every 10 days after the treatments.The results indicated that the plant growth substances caused the changes of both anatomical structure of leaf and photosynthetic characteristics.Under light microscope,we found that,compared with control,DTA,CC,and SODM increased palisade tissue thickness and ratio of palisade/spongy of leaf.The tight degree of palisade tissue arrangement,was different in treatment showing the order of SODM DTA CC CK.DTA,CC,and SODM increased the number of chloroplast single cell,granule lamella and starch grains in chloroplast,while reduced the number of osmophilic globuli in the chloroplast.SODM,DTA increased granule number in chloroplast significantly.In the investigation of photosynthetic characteristics,we found that,compared with control,DTA,SODM,and CC increased the contents of Chl a,Chl b,Chl(a+b) in leaf and the ratio of Chl b/a.DTA,SODM,and CC advanced the time to maximum leaf area index and leaf area duration(LAD),increased total LAD and photosynthetic rate during grain filling period under water stress.From above,we drew a conclusion that plant growth substances could at least partially regulate the structure of soybean organs,fibre texture and ultrastructure of soybean leaf,which is helpful to promote photosynthesis,showing the consistency between anatomical structure and physiological function.

Analysis on Dry Matter Production Characteristics of Super Hybrid Rice

Six middle-season indica hybrid rice combinations, including five super hybrid rice combinations with the high yield about 10.5 t/ha and a check hybrid rice combination Shanyou 63 with a yield potential about 9.5 t/ha, were used as materials to study the dry matter production characteristics. The super hybrid rice showed a high ability in dry matter production and accumulation and its yield enhanced with the increase of dry matter accumulation. The advantage period of dry matter production in the super hybrid rice was mainly at the middle and late growth stages compared with the check. The grain yield had no significant correlation with the dry matter accumulation before the elongation stage while had a significantly positive correlation with the dry matter accumulation from the elongation to maturity stages in super hybrid rice. There were more dry matter in vegetative organs at the heading stage in the super hybrid rice but its contribution to yield (apparent conversion percentage) was averagely 4.3 percent points lower than that in the check. For crop growth rate (CGR), the comparative advantage of super hybrid rice was at the middle and late stages, especially after flowering. Moreover, as the rising of leaf area index (LAI) and leaf area duration (LAD), CGR enhanced. The total LAD and the mean of LAD per day of super hybrid rice was about 14.79% and 10.31% higher than those of the check, respectively. The results indicate that the high yield of super hybrid rice mostly comes from the products of photosynthesis after heading, which is shown by the increased CGR at middle and later stages. It is suggested that LAD character might be used to better explain the advantage in the dry matter production of super hybrid rice than LAI.

Effects of Irrigation at Different Growth Stages on Vegetative Growth of Mung Bean, Vigna Radiata (L.) Wilczek, in Dry and Intermediate Zones of Sri Lanka

Mung bean crops in the subhumid zones of Sri Lanka experience significant drought periods. The objective of this study was to quantify the growth response of mung bean to irrigation at different phenological stages and thereby determine the optimum irrigation regime to maximize growth. Four field experiments were conducted at two sites in 1995 and 1996. The crop duration of mung bean was divided into three stages: vegetative (from germination to appearance of first flower), flowering (from appearance of first flower to 75 % pod initiation) and pod‐filling (from 75 % pod initiation to maturity). Eight treatments were devised to represent all possible combinations of irrigation at the three stages. Maximum leaf area index (ranging from 0.6 to 2.6 across treatments) and total leaf area duration were increased significantly by irrigation during the vegetative stage. Specific leaf weight decreased and maximum total crop biomass (150–400 g m−2) increased with the number of stages irrigated. Irrigation decreased the absolute root biomass and increased the shoot:root ratio. It is concluded that, in this agroclimatic zone of Sri Lanka, irrigation of mung bean during the vegetative stage is critical for maximizing leaf area. However, biomass production can be maximized by increasing the number of stages irrigated irrespective of irrigation at any specific stage.

Leaf Area Duration of Oat at High Latitudes

AbstractContribution of leaf area duration (LAD) to grain yield during the short growing season characteristic of northern latitudes may differ from the marked impact it has at lower latitudes. Three experiments (exps) were carried out at Viikki Experimental Farm, University of Helsinki, Finland (60° 13′N) to compare associations between main shoot and tiller LAD with grain yield, yield components and morpho‐physiological traits characterizing plant stand structure. This was done using correlation analysis and principal component analysis (PCA) for data from trials conducted during 1993–1995. Exp I included three N fertilizer rates (80, 120, 160 kg N ha−1), three seeding rates (250, 500, and 750 seeds m−2), and tall, moderate, semi‐dwarf, and dwarf oat lines. Exp II incorporated two N fertilizer rates (80 and 120 kg ha−1), three seeding rates (400, 600, and 800 seeds m−2), and naked and hulled oat lines, and exp III, foliar applications of plant growth regulators [control, chlormequat chloride (CCC), and ethephon], and dwarf, naked, and conventional oat lines. LAD for main shoots and tillers [calculated as ∫ LAI d T, where T is cumulated degree days from seedling emergence to yellow ripening (dd °C)] and 12 morpho‐physiological traits were measured. Oat was not able to benefit from high main shoot LAD if drought occurred at grain‐fill, but in the absence of severe drought or if it occurred at pre‐anthesis, high LAD favoured yield formation. Tiller LAD had a negative impact, if any, on grain yield in cases of an inverse relationship between tiller LAD and yield components on main shoots was recorded. Use of low seeding rates resulted in improved ability of total LAD to contribute to dry‐matter production, but was not associated with grain yield. Low seeding rates enhanced formation of high tiller LAD, which was not able to compensate for grain yield reduction caused by fewer main shoots. Foliar application of CCC and ethephon tended to increase the proportion of LAD production by tillers at the expense of grain yield, which can be attributed to lower post‐anthesis precipitation. Oat types differed in main shoot and tiller LAD. Disadvantageous characteristics of naked oat, such as low single groat weight, were not associated with insufficient main shoot LAD. High tiller LAD in naked lines and the Minnesota‐adapted dwarf line that was not associated with high tiller grain yield in naked lines, in particular, indicates that tiller growth was enhanced at the expense of grain yield production. Application of N fertilizer at various rates did not have any effect on LAD.

Growth, development and yield of five sunflower hybrids

Studies were conducted to assess the physiological basis of variation in yield among five genotypes during the summer seasons of 1987 and 1989, using the techniques of growth and yield analysis. The sowing of second-crop sunflowers allowed maximum values of total dry matter to be reached that were quite similar for both years, between 581 and 821 g m −2. Total dry matter yields in 1987 were reached with lower maximum leaf area index (LAI) and lower total leaf area duration (LAD) than in 1989. In both years of testing, the hybrid SH-222, which has a somewhat longer cycle than the other hybrids, stood out not only for its maximum LAI, but also for its higher LAD after flowering, total LAD and maximum crop growth rate (CGR), and for maximum and final total dry matter. The high temperatures and low relative humidities during the two seasons affected pollination and formation of achenes, especially in 1987 and in the cultivars showing low autocompatibility (Arbung-133 and SH-31), which had the greatest dry weight per 1000 fertile achenes. There were positive significant correlations between maximum CGR, total LAD, number of fertile achenes per head and concentration of oil in the achenes, and yield of achenes. However, the correlation with the protein concentration in the achenes was negative. LAD after flowering, head fertility and maximum of total dry matter were also positively correlated with achene yield, but with significant statistics in only one of the two years studied. Their correlations were negative with the dry weight of 1000 fertile achenes.

Effects of different water regimes on field-grown determinate and indeterminate faba bean ( Vicia faba L.). I. Canopy growth and biomass production

Soil water shortage has been identified as a major constraint in increasing faba bean production. However, high water availability could cause excessive vegetative growth in indeterminate faba bean. Therefore, the present study was conducted with the objectives of quantifying canopy growth and biomass production of determinate and indeterminate faba bean under a range of water availability and thereby finding the suitability of different cultivars for different water regimes. Two field experiments were carried out in 1989 and 1990 at Reading, United Kingdom, using the determinate cultivar ‘Tina’ and the indeterminate cultivar ‘Gobo’. Rainshelters and trickle irrigation were used to establish four different water regimes: unsheltered and well-irrigated (W 1); sheltered at flowering and subjected to post-flowering water stress (W 2); sheltered throughout the season and subjected to continuously-increasing water stress (W 3); open rainfed (W 4). Leaf initiation, expansion and biomass production were significantly reduced by soil water deficits. A linear relationship was observed between final biomass and total leaf area duration. The relationship was common for all water treatments and both cultivars. This indicated that for the two cultivars tested, the effects of water stress were more on canopy size than on photosynthetic efficiency. A constant photothermal duration, which was similar for both cultivars, determined the durations from seedling emergence to flowering and maturity. Crops were planted 3 weeks earlier in 1990 than in 1989. Due to lower temperatures and photoperiods during the early part of growth, the 1990 crops took a longer duration to flower and mature as compared to 1989 crops. In the absence of water stress, a longer post-flowering duration allowed the indeterminates to develop a larger canopy and achieve a high final biomass (21 t/ha in 1990). The determinates were unable to produce a high biomass due to cessation of leaf production after flowering. In the shorter 1989 season, the determinate W 1 had a higher biomass (12 t/ha) than the indeterminate W 1 (10 t/ha). With increasing post-flowering water stress, the final biomass was mainly determined by the LAI at flowering. A higher LAI at flowering produced a greater final biomass. Only the indeterminates had the flexibility in phenology to take advantage of the post-flowering irrigation in W 2. It is concluded that if the whole biomass is to be utilized, indeterminate faba bean are more suitable for early-spring plantings with adequate water availability and for both early- and late-spring plantings under increasing water stress. Determinate faba bean are recommended only for late-spring plantings at sites with adequate water availability which could be predicted by analysis of past rainfall data. The determinates had less season-to-season variability in biomass. Efforts should be made to increase their overall biomass production potential while retaining this stability.

Comparative adaptation of canola ( Brassica napus) and Indian mustard ( B. juncea) to soil water deficits: Plant water relations and growth

The work reported in this paper was designed to describe how mustard achieves greater dry matter production and yield compared to canola under water-deficit conditions. The work was based on three field experiments which each used at least three cultivars or lines of each species. Mustard leaves had greater turgor pressure than those of canola (up to 0.36 MPa greater). Mustard's growth advantage increased with increasing stress with total leaf area duration being longer (1.5 times) and crop growth rates greater (up to 2 times) than those of canola under high water deficits. These differences in growth were positively correlated with leaf turgor. Mustard also grew better under low water deficits particularly early in the season; these differences were associated with differences in early season leaf morphology (lower specific leaf weights) rather than with differences in the partitioning of assimilate to leaf growth. However, the early growth differences were also linked with differences in turgor, suggesting that mustard's turgor advantage at least partially explained its superior early vigour. It is concluded that the greater leaf turgor of mustard is a key factor in this crop's adaptive advantage under high water deficits, allowing it to maintain longer leaf area duration and thereby greater dry weight and seed yield compared to canola.

Ozone Impacts on Seasonal Foliage Dynamics of Young Loblolly Pine

Abstract Effects of above- and below-ambient levels of ozone (O3) on the production, abscission, and duration of foliage of young loblolly pine (Pinus taeda L.) grown in open-top chambers were examined in the Piedmont of North Carolina. Assessments of fascicle elongation and number were made at frequent intervals during 1988, 1989, and 1990 for all 1988 primary flushes on the stem and at a branch position. Ozone treatment had little effect on overall foliage production; however, all elevated O3 levels reduced foliage retention. Foliage abscission for most flushes was initiated when cumulative O3 dose exceeded 130 to 220 ppm-hr regardless of crown position for trees exposed to ambient and above-ambient O3 levels. Reductions in leaf area duration of the 1988 cohort were observed at ambient and higher O3 levels. Total leaf area duration was 22 and 25% greater for the stem and branch positions in the charcoal-filtered as compared to nonfiltered treatments. The greater duration in charcoal-filtered chambers resulted from significantly greater retention into the third growing season. Foliage development and ozone responses at the branch position were more representative of the whole crown than those at the stem position. For. Sci. 38(1):102-119.

Flag Leaf and Peduncle Area Duration in Relation to Winter Wheat Grain Yield1

AbstractInformation on the photosynthetic area duration in winter wheat (Triticum aestivum L. em Thell.) is important in breeding programs for yield advancement and large numbers of data must be taken for the data to be meaningful. A 2‐year field study (1973 and 1974) was conducted at the Agricultural Experiment Station, Oklahoma State Univ., Stillwater, Okla. It was conducted to obtain information on flag leaf and peduncle area duration as selection indexes in relation to yield, tiller number, kernels/spike, and kernel weight in winter wheat and to investigate the response of five winter wheat cultivars to selected N levels and seeding rates higher than presently used for grain production. A split‐split plot design with four replications was used for the study. Nitrogen levels comprised main plots, cultivars were sub‐plots, and seeding rates were sub‐sub plots. The levels of N were 67, 134, and 202 kg N/ha, and the seeding rates were 67, 100, and 134 kg/ha. The five hard red winter wheat cultivars were ‘Tam W 101,’ ‘Palo Duro,’ ‘Danne,’ ‘Centurk,’ and ‘Caprock.’All the traits measured differed between the two crop seasons, and a significant year by cultivar interaction suggested the presence of genotype by environment interaction. Differences among N levels were not significant probably because of the high residual amounts of available nitrogen at the experimental site, the lowest level of applied N was adequate for crop growth. The highest seeding rate (134 kg/ha) reduced grain yield, kernels per spike, and flag leaf area duration. Even though the growing conditions differed between the 2 years of the study, peduncle area duration and flag leaf area duration showed a positive correlation with grain yield, kernel weight, and a negative relationship with kernels per spike. These data suggested the use of peduncle area duration and/or flag leaf area duration as selection criteria in breeding for increased grain yield potential. These readings would be more rapid than total leaf area duration; and using selected photosynthetic leaf area indexes in a breeding program for yield, data could be obtained on many more genotypes. The data also support the use of kernel weight as a selection factor for increasing grain yield.

Physiology of seed yield in field beans (Vicia faba L.): II. Dry-matter production

SummaryDry weight per unit area was related to plant density differences and leaf area duration (LAD) up to pod-setting (late June). Total dry weight and seed dry weight at maturity were not related to total LAD or LAD after pod setting. Seed yield at a node was closely correlated with leaf area at the same node (r = 0·67 to 0·94).Differences in net assimilation rate (NAR) between varieties were not significant. A substantial rise in NAR in July-early August was attributed to additional photosynthesis by pods.