•DHEAP is a novel plant growth regulator.•DHEAP improved maize lodging resistance.•DHEAP shaped a compact maize plant type.•DHEAP is helpful to increases summer maize planting density in NCP.
...Increasing the planting density (PD) of maize (Zea mays L.) crops is the most efficient method for enhancing maize grain yield, but supra-optimum PD leads to an increase in lodged maize, which alters the maize canopy structure. In this study, N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt (DHEAP, a single compound), a novel plant growth regulator, was sprayed at the seven-expanded-leaf stage under two different PDs (75,000, and 90,000 plants ha-1) using two maize hybrids, ZD958 (lodging-resistance) and XY335 (lodging-susceptible), to reduce maize lodging rates and improve the maize canopy structure under high PD. After DHEAP treatment, the maize lodging rate of ZD958 and XY335 decreased by 70.87% and 75.22%, respectively, through a change in the morphological structure (i.e., reduced plant and ear heights and increased mean tilt angle) and an improvement in the basal internode quality (i.e., increased diameter, dry weight per unit length, crushing strength, cellulose content, lignin content, and vascular area, and reduced length). In addition, DHEAP treatment significantly reduced gibberellin (GA3) contents in maize basal internodes. Moreover, the increase in the mean tilt angle (MTA) above the maize ear leaf after DHEAP treatment improved the light penetration in the middle leaf strata, which increased the chlorophyll content (SPAD), net photosynthetic rate (Pn), and Rubisco enzyme activities. Finally, DHEAP treatment increased the grain yield of ZD958 and XY335 under 90,000 PD by 22.28% and 43.14%, respectively. Thus, it was concluded that the spraying of DHEAP effectively reduced maize lodging rates and improved the photosynthetic performance of the maize ear leaf, which increased maize grain yield under high PDs.
The bark in some forest species may represent a significant volume of the trunk, demanding the use of efficient methods to estimate bark volume indirectly through equations. The aim of this study was ...to evaluate bark volume and thickness in teak (Tectona grandis) trees planted at different densities. Volume data were used to evaluate the percentage of bark in different portions of the trunk. Averages were compared by the Tukey test (p < 0.05%) and regression analysis (polynomial model) was used to predict bark thickness along the trunk. The effect of spacing on bark thickness was compared by the model identity test. The percentage of bark in more densely planted teak trees was higher. The percentage of bark decreases from the base to the top of the tree trunk, with an average volume of green bark reaching 24% to 30% of the total volume. Increasing spacing promotes higher absolute average bark thickness.
Matching of maize growth with solar radiation is of great importance for achieving high yield. We conducted experiments using different maize cultivars and planting densities under different solar ...radiations during grain filling to quantitatively analyze the relationships among these factors. We found that a decrease in solar radiation after silking caused a drop in maize grain yield and biomass, with lower solar radiation intensities leading to worse grain yields and biomass. Cultivar ZD958 was more sensitive to solar radiation changes than cultivar XY335; slight decreases in solar radiation (i.e., 15% shading) caused significant declines in ZD958 grain yield. When total solar radiation during grain filling was less than 486.9 MJ m
for XY335 and less than 510.9 MJ m
for ZD958, the two cultivars demonstrated high yields at lower planting density of 7.5 × 10
plants ha
; average yields were 13.36 and 11.09 Mg ha
, respectively. When radiation intensities were higher than 549.5 MJ m
for XY335 and higher than 605.8 MJ m
for ZD958, yields were higher at a higher planting density of 12 × 10
plants ha
, with average yields of 20.58 Mg ha
for XY335 and 19.65 Mg ha
for ZD958.
Abstract Sorghum aphid, Melanaphis sorghi (Theobald) have become a major economic pest in sorghum causing 70% yield loss without timely insecticide applications. The overarching goal is to develop a ...monitoring system for sorghum aphids using remote sensing technologies to detect changes in plant-aphid density interactions, thereby reducing scouting time. We studied the effect of aphid density on sorghum spectral responses near the feeding site and on distal leaves from infestation and quantified potential systemic effects to determine if aphid feeding can be detected. A leaf spectrometer at 400–1000 nm range was used to measure reflectance changes by varying levels of sorghum aphid density on lower leaves and those distant to the caged infestation. Our study results demonstrate that sorghum aphid infestation can be determined by changes in reflected light, especially between the green–red range (550–650 nm), and sorghum plants respond systemically. This study serves as an essential first step in developing more effective pest monitoring systems for sorghum aphids, as leaf reflection sensors can be used to identify aphid feeding regardless of infestation location on the plant. Future research should address whether such reflectance signatures can be detected autonomously using small unmanned aircraft systems or sUAS equipped with comparable sensor technologies.
Food equivalent unit (FEU) is a vector used to measure the value of food based on its calorie and protein content and their digestibility. However, the optimal planting density and N application rate ...for maximizing the FEU yield (FEUY) of forage maize (Zea mays L.) is still poorly understood in the fast-growing animal husbandry regions of the Chinese Loess Plateau. Here, a 2-year consecutive field experiment was conducted to explore the impacts of planting density, N application rate, and their interactions on growth, dry matter yield (DMY), forage quality, and FEUY of a dominant forage maize cultivar. Planting density significantly affected the stem diameter, LAI, DMY, and dry matter allocation (DMA) of the leaf. Initially, increasing the N rate increased the stem diameter, LAI, FEUY, and DMY of forage maize and then decreased. The stem diameter, LAI, FEUY and above-ground DMY peaked under 180 kg∙ha−1 N in both years. Moreover, N application significantly increased the crude protein content of the whole plant and decreased the acid detergent fiber content. The surface fittings of the 2-year study indicated that 110,000 plants∙ha−1 (plant density) and 171.2 kg∙ha−1 (N rate) obtained the greatest DMY (19.0 t∙ha−1). The grade index (a comprehensive evaluation index for forage quality) peaked at 15.4 MJ∙d−1 under 94,000 plants ha−1 and 270 kg∙ha−1. The 110,000 plants∙ha−1 plant density and 181.5 kg∙ha−1 N rate jointly maximized the FEUY (11,125.4 FEU∙ha−1), maintaining 99.9 % of the maximum DMY and 97.5 % of the maximum grade index. Thus, 110,000 plants∙ha−1 plant density and 181.5 kg∙ha−1 N rate are recommended for high-productivity forage maize production, without notably compromising dry matter yield and feed quality. This research is conducive to advancing the coordinated development of forage crop cultivation and herbivorous livestock farming in semi-arid rainfed areas.
•The effect of N rates on grade index of forage maize is greater than that of planting density.•Density 110,000 plants∙ha−1 and N rate 181.5 kg∙ha−1 maximized food equivalent unit yield.•The optimal maintained 99.9 % of the yield and 97.5 % maximum grading index.
Background. Taro (Colocasia esculenta) can be grown in a variety of environmental and edaphic conditions, but it is most typically grown in wetlands. The optimal conditions for its growth are two ...water regimes i.e., waterlogged or flooded conditions to dryland or unflooded conditions. An important criterion in crop yield is water use efficiency (WUE), and it has been suggested that crop production per unit of water used can be increased. Objectives. To determine the WUE of taro in Kenya’s sub-humid environment under different watering regimes and planting densities. Methodology. A study was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) – Embu Research Centre, during the long rains (LR) 2021, short rains (SR) 2021/2022, and long rains (LR) 2022. A factorial experiment with a split-plot layout arranged in a completely randomized block design was used. The main factor was the irrigation levels while the sub-factor was the planting density, with three replications. The three irrigation levels were at 100 %, 60 %, and 30 % based on the field capacity (FC). The planting densities used were 0.5m × 0.5m (40,000 plants ha-1), 1m × 0.5m (20,000 plants ha-1), and 1m × 1m (10,000 plants ha-1), representative of high, medium, and low planting densities respectively. Results. The WUE was influenced by season and watering regime (P < 0.05). The 30% FC had the highest WUE with the 100 % FC having the lowest. The high WUE under 30 % FC (19.40 kg ha-1mm-1) was associated with the high biomass (1.97 kg) and low water use (2269.41 mm) recorded under limited water conditions. The medium (1m × 0.5m) planting density attained the highest WUE (12.16 kg ha-1mm-1) with the high planting density (0.5m × 0.5m) having the lowest (10.65 kg ha-1mm-1), though no significant differences were recorded. Implications. The varying watering regimes and planting densities in this study have different capacities to utilize the supplied water. The total taro biomass increased with decrease in water supplied and in turn maximized the water use efficiency. Conclusion. To achieve the highest yield per unit of water consumed, a watering regime of 30 % FC and a planting density of 1 m × 0.5 m (20,000 plants ha-1) is recommended.
The oil palm yield depends on its genetic and the interaction with environmental factors is affected by spatial arrangement of palm trees. The research objectives are to determine the effect of ...population density and planting year on oil palm productivity and vegetative growth. This research uses a factorial design arranged with a randomized complete design. Secondary data are palm productivity, fresh bunch number and bunch weight that were collected for three years (2019—2022). Primary data are stem height, frond length, and stem gird which were measured on 90 trees for each treatment combination. There are nine combinations with 810 palm trees that were sampled from 27 estate blocks (30 hectares for one block). The results showed that productivity and amount of oil palm FFB at densities ≥ 142, 136-141, and ≤ 135 SPH and planting years 2007, 2009 and 2011 (mature crop 12-15, 10-13, and 8-11 years) did not show significant differences. The heavier bunch weight was produced palm tree planted in 2007 with density ± 135 trees.ha-1.
The exploitative segregation of plant roots Cabal, Ciro; Martínez-García, Ricardo; de Castro Aguilar, Aurora ...
Science (American Association for the Advancement of Science),
12/2020, Letnik:
370, Številka:
6521
Journal Article
Recenzirano
Plant roots determine carbon uptake, survivorship, and agricultural yield and represent a large proportion of the world's vegetation carbon pool. Study of belowground competition, unlike aboveground ...shoot competition, is hampered by our inability to observe roots. We developed a consumer-resource model based in game theory that predicts the root density spatial distribution of individual plants and tested the model predictions in a greenhouse experiment. Plants in the experiment reacted to neighbors as predicted by the model's evolutionary stable equilibrium, by both overinvesting in nearby roots and reducing their root foraging range. We thereby provide a theoretical foundation for belowground allocation of carbon by vegetation that reconciles seemingly contradictory experimental results such as root segregation and the tragedy of the commons in plant roots.
Optimal plant density and nitrogen (N) application rate are important to achieve high maize yield. High plant density increases plant-plant competition for light and nutrients. However, too much ...applied N promotes excessive vegetative growth and delays maturity, resulting in low N use efficiency (NUE) and potentially environmental problems. The physiological and molecular mechanisms behind the interaction between plant density and N application rate are largely unknown.
We hypothesized that simultaneously improving maize yield and NUE depends on fine regulation of nitrogen partitioning in response to the interaction between nitrogen applications and plant densities.
With a 2-year field experiment, we performed phenotypic, physiological, and gene expression analyses under two plant densities (low density of 60,000 plants ha-1 and high density of 90,000 plants ha-1) and three nitrogen application levels 115 (N1), 190 (N3) and 430 (N4) kg N ha-1 in the high N-responsiveness maize cultivar ZD958.
By labeling maize with 15N, 2-year results showed that both 15N uptake per plant and 15N partitioning to ear decreased under high-density conditions. Compared to N1 treatment, application of N to N3/N4 level increased maize yield by 13.9%− 43.2%, which can be explained by bigger root angle, larger leaf area and lower lodging rate under high density condition. In addition, results in 2019 experiment showed that yield, NUE, nitrogen allocation to stem and the expression of some N transporter genes were regulated by the interaction between nitrogen applications and plant densities. Compared to the N4 treatment, N3 treatment has a 55.8% reduction in N, a tendency of increase in population yield, and increased NUE by 59.6% and 63.0% in low-density and high-density plantings, respectively. Our proposed model suggested that the appropriate N supply increased NUE by either increasing N translocation from leaves to ears under low-density conditions or by increasing N allocation to ears rather than to stems under high-density conditions.
Based on correlation analysis, N allocation/translocation and expression of nitrogen transporter genes could be used as biomarkers to indicate appropriate levels of N application under different planting densities, and are thereby important for the simultaneously improving ZD958 yield and NUE in intensive agriculture.
Palmer amaranth germination and emergence occur throughout the growing season; however, little is known about the impact of late-emerging Palmer amaranth on sorghum, a major crop in Kansas. Field ...trials were conducted in 2016 and 2017 to measure grain sorghum and late-emerging Palmer amaranth’s response to sorghum planting density and nitrogen rate. Trials were comprised of weed-free and weedy sorghum as main plots, three sorghum planting densities as sub-plots, and three nitrogen rates as sub-sub-plot treatments laid in a randomized complete block design with a split–split-plot arrangement. Weedy sorghum was infested with late-emerging Palmer amaranth only. Weed-free sorghum outyielded its weedy counterpart by 42.2%. At the high sorghum planting density (296 400 plants ha−1), applying 112 kg N ha−1 did not improve grain yield or decrease Palmer amaranth’s number, height, and biomass, but increased sorghum head number and height. Altogether, our findings suggest that increasing sorghum planting density and nitrogen rate in an irrigated environment did not facilitate Palmer amaranth control. Strategies for long-season Palmer amaranth control are needed to protect sorghum yield from weed competition.
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