Ecological Adaptability of Introduced Bamboo Species

To enrich ornamental bamboo species in south Henan, 22 ornamental bamboo species were introduced from Anji County, Zhejiang Province, and quadrat survey was adopted to study the ecological adaptability of the introduced species. The results showed that 14 of the introduced species survived in south Henan, and particularly Phyllostachys vivax f. aureocaulis, Phyllostachys vivax f. huanwen, Phyllostachys aureosulcata f. spectabilis, Bambusa multiplex, Phyllostachys nigra, Pseudosasa amabilis, Pleioblastus maculatus showed good performance in height growth, diameter growth and resistance, so these species are most suitable for the promotion in south Henan.

Patterns of above-and belowground biomass allocation in China's grasslands:Evidence from individual-level observations

Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.

Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species,belonging to three common functional groups (forbs,grasses and sedges) at subalpine (3700 m ASL),alpine (4300 m ASL) and subnival (≥5000 m ASL) sites were examined to test the hypothesis that at high altitudes,plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts,especially storage organs,as altitude increases,so as to geminate and resist environmental stress.However,results indicate that some divergence in biomass allocation exists among organs.With increasing altitude,the mean fractions of total biomass allocated to aboveground parts decreased.The mean fractions of total biomass allocation to storage organs at the subalpine site (7%±2% S.E.) were distinct from those at the alpine (23%±6%) and subnival (21%±6%) sites,while the proportions of green leaves at all altitudes remained almost constant.At 4300 m and 5000 m,the mean fractions of flower stems decreased by 45% and 41%,respectively,while fine roots increased by 86% and 102%,respectively.Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation,while sedges showed opposite trends.For all three functional groups,leaf area ratio and leaf area root mass ratio decreased,while fine root biomass increased at higher altitudes.Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots,while the proportion of leaves remained stable.It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots.In contrast to forbs and grasses that had high mycorrhizal infection,sedges had higher single leaf area and more root fraction,especially fine roots.

Effects of seed furrow liquid spraying device on sowing quality and seedling growth of maize

The two cultivation patterns,no-tillage and ridge cultivation,are widely used in maize planting in Northeast China.However,the seed bounce in the falling process and drought seriously at the seedling stage often occur to affect the sowing quality,mean emergence time,percentage of emergence,root biomass,aboveground biomass and root shoot ratio of maize,and eventually reduces the grain yield.To solve the problems,a seed furrow liquid spraying device was designed and thereby the effects of spraying water volumes[0 L/m(V0),0.6 L/m(V1),1.2 L/m(V2)and 1.8 L/m(V3)]and nozzle types[conical nozzle(N1)and sectorial nozzle(N2)]on the sowing quality and seedling growth of maize were studied.The water volume and nozzle type had significant effects on the sowing quality(QR,CV,LD),not seedling growth(MET,PE,RB,AB,RSR)(p<0.05).Spraying water into seed furrow further humidified the soils around the maize seeds,effectively suppressing the bounce and rolling of seed and significantly promoting the growth and development of seeds.The sowing quality in the N2 treatment was significantly better than that in the N1 treatment.The qualified rate of seed spacing was increased with the increase of the water volume(V3>V2>V1>V0).However,the variability coefficient of seed spacing and lateral deviation of seed position were the opposite.The larger spraying water volume led to shorter mean emergence time(V0>V1>V2>V3)and higher percentage of emergence(V3>V2>V1>V0).The root biomass and aboveground biomass increased significantly with the enlargement of spraying water volume.Under different water volumes,the root shoot ratio differed significantly.The plants in the V1,V2 and V3 treatments had lower root shoot ratios compared with the V0 treatment.The increase of spraying water volume significantly reduced the root shoot ratio.The seed furrow liquid spraying device provides a reference for improving sowing quality and promoting seedling growth.

Closely related allopatric Podalyria species from the Core Cape Subregion differ in their mechanisms for acquisition of phosphorus,growth and ecological niche

Aims In the Core Cape Subregion(CCR),a Mediterranean-climate ecosystem with infertile soils,the legume species Podalyria calyptrata and P.burchellii are in a separate clade to P.leipoldtii and P.myrtillifolia.The closely related species are allopatric,and with the west-east climate gradient and variation in soil nutrient availability in the CCR,it was hypothesized that the two closely related allopatric species would differ in their ecological niche and root:shoot ratio,specific root length(SRL)and organic acid exudation responses to phosphorus(P)supply.Methods With increasing P supply in the glasshouse,we measured plant biomass,leaf nitrogen([N]),[P],root morphology and release of organic acids.We determined species soil and leaf[N]and[P]and climate in field sites.Important FindingsAt low P supply,P.calyptrata roots exuded more organic acids than P.burchellii which instead produced roots with a greater SRL,and P.myrtillifolia allocated more biomass to roots than P.leipoldtii.In the field,leaf[P]and climate suggested that P.leipoldtii occupied the most oligotrophic niche followed by P.burchellii and then P.calyptrata and P.myrtillifolia.Closely related allopatric species differed in their mechanisms for P-acquisition and ecological niche,indicating that the environment overrides phylogeny in determining P-acquisition traits for these species,and suggesting that climate regulates nutrient availability,driving distribution and speciation.

Nondestructive estimation of bok choy nitrogen status with an active canopy sensor in comparison to a chlorophyll meter

Precise estimation of vegetable nitrogen(N)status is critical in optimizing N fertilization management.However,nondestructive and accurate N diagnostic methods for vegetables are relatively scarce.In our two-year field experiment,we evaluated whether an active canopy sensor(GreenSeeker)could be used to nondestructively predict N status of bok choy(Brassica rapa subsp.chinensis)compared with a chlorophyll meter.Results showed that the normalized difference vegetation index(NDVI)and ratio vegetation index(RVI)generated by the active canopy sensor were well correlated with the aboveground biomass(AGB)(r=0.698–0.967),plant N uptake(PNU)(r=0.642–0.951),and root to shoot ratio(RTS)(r=-0.426 to-0.845).Compared with the chlorophyll meter,the active canopy sensor displayed much higher accuracy(5.0%–177.4%higher)in predicting AGB and PNU and equal or slightly worse(0.54–1.82 times that of the chlorophyll meter)for RTS.The sensor-based NDVI model performed equally well in estimating AGB(R2=0.63)and PNU(R2=0.61),but the meter-based model predicted RTS better(R2=0.50).Inclusion of the days after transplanting(DAT)significantly improved the accuracy of sensor-based AGB(19.0%–56.7%higher)and PNU(24.6%–84.6%higher)estimation models.These findings suggest that the active canopy sensor has a great potential for nondestructively estimating N status of bok choy accurately and thus for better N recommendations,especially with inclusion of DAT,and could be applied to more vegetables with some verification.

Screening of tall fescue genotypes for relative water content and osmotic potential under drought stress

Background:Tall fescue(Festuca arundinacea Schreb.)is an important coolseason perennial grass.Its persistence and forage yield can be severely affected by drought stresses during the hot,dry summers of the southern USA.Methods:One thousand tall fescue genotypes were evaluated in the greenhouse for high relative water content(RWC)and low cell sap osmotic potential(OP).Fifty contrasting genotypes for the two traits were identified and used in further greenhouse and field studies.These genotypes were also screened with 30%PEG8000.Root and shoot characteristics were studied in 10 genotypes.Results:The genotypes differed for RWC(33.7%–97.3%,mean:79.7%)and had an almost fivefold difference in OP(−0.5 to−2.4 MPa,mean:−1.2 MPa).Significant variation(p<0.001)for the main effects of environment and genotypes was found for RWC and OP.Apart from the greenhouse trial,no correlation was found between RWC and OP,indicating that differences in RWC might have been due to factors other than osmotic adjustment.Genotypes with either long roots or high root weights,and high root/shoot ratios demonstrated high RWC and low OP.Conclusions:Genotypes with consistently high RWC and low OP were identified and used for the development of mapping populations and transcriptome studies.