Sensitivity of Functional Traits to Environmental factors in a Karst Plant Community

In this study, the plant communities at five succession stages (herbage, herbage-shrub, shrub, tree-shrub, and tree) in the Zhenning Karst Plateau area of Guizhou were examined. The changes of plant functional characteristics in different succession stages were analyzed, as was the relationship between functional traits and environmental factors. The main results include the following. (1) During the succes-sion process, plant height, leaf dry matter mass, leaf area, leaf nitrogen content, and leaf phosphorus content gradually increased, whereas leaf thickness and specific leaf area decreased, and leaf C:P ratio and leaf N:P ratios did not change significantly. (2) Soil organic matter, soil total nitrogen, soil total phosphorus, soil C:N, soil C:P, and soil C:K increased at first and then decreased, reaching a peak at the tree-shrub stage. Soil total potassium fluctuated and soil bulk density gradually decreased and reached the lowest value at the tree-shrub stage. (3) Redundancy analysis (RDA) showed that the plant community shifted from a nutri-ent-poor soil environment to a nutrient-rich environment. Soil total phosphorus, soil C:K, soil organic mat-ter, soil C:N, and soil bulk density were the key environmental factors affecting the change of functional traits. (4) Structural equation modeling suggests that that specific leaf area and leaf nitrogen content had more sensitive responses to soil nutrient resources and environmental factors, respectively.

Estimation of leaf nitrogen levels in sugarcane using hyperspectral models

ABSTRACT: Sugarcane is a good source of renewable energy and helps reduce the emission of greenhouse gases. Nitrogen has a critical role in plant growth; therefore,estimating nitrogen levels is essential, and remote sensing can improve fertilizer management. This field study selects wavelengths from hyperspectral data on a sugarcane canopy to generate models for estimating leaf nitrogen concentrations. The study was carried out in the municipalities of Piracicaba, Jaú, and Santa Maria da Serra, state of São Paulo, in the 2013/2014 growing season. The experiments were carried out using a completely randomized block design with split plots (three sugarcane varieties per plot [variety SP 81-3250 was common to all plots] and four nitrogen concentrations [0, 50, 100, and 150 kgha-1] per subplot) and four repetitions. The wavelengths that best correlated with leaf nitrogen were selected usingsparse partial least square regression. The wavelength regionswere combinedby stepwise multiple linear regression. Spectral bands in the visible (700-705 nm), red-edge (710-720 nm), near-infrared (725, 925, 955, and 980 nm), and short-wave infrared (1355, 1420, 1595, 1600, 1605, and 1610 nm) regions were identified. The R² and RMSE of the model were 0.50 and 1.67 g.kg-1, respectively. The adjusted R² and RMSE of the models for Piracicaba, Jaú, and Santa Maria were 0.31 (unreliable) and 1.30 g.kg-1, 0.53 and 1.96 g.kg-1, and 0.54 and 1.46 g.kg-1, respectively. Our results showed that canopy hyperspectral reflectance can estimate leaf nitrogen concentrations and manage nitrogen application in sugarcane.

Effect of Prosopis Farcta, Urtica Dioica and Disper root on Vegetative Growth, Nutrients Contents of cv. Shahreban Pomegranate Transplant

This research was conducted on pomegranate transplants in a lath house during the growth season of 2020 of college of Agricultural engineering science, university of Duhok, to investigate the impact of spraying of Prosopis Farcta, Urtica Dioica and Disper root with 0,100, and 200 mg.L-1 concentration, with 0,100, and 200 mg.L-1 concentration and with (0, 75, and 150 mg.L-1) concentration respectively, on vegetative growth, nutrients contents of pomegranate transplants. The collected data indicate that the spraying of Prosopis Farcta extract, Urtica Dioica and Disper root especially at 200, 200, and 150 mg.L-1 respectively resulting in a considerable increase in the majority of the examined parameters. At high concentrations, the interaction of three examined components resulted in the maximum values of branches number 14.57, transplant height 143.67 cm, leaves number 157.33, Chlorophyll 48.97, Roots number 10, Root length 42.67 cm, leaf nitrogen content 2.507 %, phosphorus 0.267 % and potassium 1.433 %.

Eco-friendly soil amendments improve growth, antioxidant activities, and root colonization in lingrain (Linum Usitatissimum L.) under drought conditions

This study’s primary purpose was to investigate the possible amelioration of limited irrigation conditions by mycorrhiza (AMF), vermicompost, and green manure for lingrain plants. This experiment was accomplished as a factorial based on the completely randomized design with three replications. The first factor was green manure (without green manure and with Trifolium pratense as green manure); the second factor consisted of Rhizophagus irregularis mycorrhiza, vermicompost, a combination of mycorrhiza and vermicompost and none of them, and also the third factor was irrigation regime (full irrigation and late-season water limitation). Green manure, vermicompost, and mycorrhiza single-use enhanced the plant’s underwater limitation conditions compared to the control. However, vermicompost and green manure or mycorrhiza developed a positive synergistic effect on most traits. Combining green manure with the dual fertilizer (mycorrhiza + vermicompost) resulted in the vermicompost and mycorrhiza synergistic effects, especially under limited irrigation. Consequently, the combination of green manure, mycorrhiza, and vermicompost experienced the highest amount of leaf relative water content, root colonization, leaf nitrogen, chlorophyll a, chlorophyll b, carotenoids, antioxidant enzymes activity, grain yield, and oil yield, which would lead to more resistance of plants to limited irrigation conditions.

The effect of nitrogen source and quantity on disease expression of Neonectria ditissima in apple

The effects of nitrogen on the interaction between apple trees and European canker caused by Neonectria ditissima are not well understood. Previous field and laboratory studies have shown that nitrogen affects N. ditissima disease development, germination and germ-tube growth in vitro but the type of nitrogen source has not been examined in vivo. Therefore, the aim of this study was to determine the effects of root-applied nitrogen from different sources on the development of European canker on inoculated potted trees. One-year-old ‘Royal Gala’ trees were planted in a low-nitrogen growth substrate and treated with a range of concentrations of calcium ammonium nitrate (CAN) or other nitrogen sources (Ca(NO3)2, KNO3, (NH4)2SO4, NH4NO3, urea, YaraMila™) at equivalent molar rates of nitrogen as the highest CAN treatment. Treatments were applied during the growing season (Nov to May). The control treatment received no applied nitrogen. Bud and leaf scar wounds were inoculated at leaf fall with N. ditissima conidia. Tree growth and health, disease progression and leaf nitrogen content were monitored. The rate of nitrogen application affected tree diameter and leaf nitrogen content while the nitrogen source mainly affected tree survival, powdery mildew incidence, leaf weights, leaf nitrogen and European canker symptom expression. Trees treated with (NH4)2SO4 had the lowest survival rates and highest leaf nitrogen content. Disease expression was highest with NH4NO3 and lowest with KNO3 applications. The control plants (which received no additional nitrogen), showed the least amount of both growth and disease expression. Applications of CAN, even at the lowest rate (20 g), increased disease susceptibility. Increasing rates of CAN applications did not significantly increase disease incidence. Nitrogen concentration is an important factor in the disease development of European canker of apple. Field evaluation is recommended to further validate these results.