Plant Physiology

Nitrogen (N) and phosphorus (P) and N: P ratio in terrestrial plants and the patterns at a large geographical scale are an important issue in ecological stoichiometry. In particular, it is essential to know that for a single species, how the N: P stoichiometry varies with climatic ...

Enzyme activity depends largely on environmental conditions such as temperature and pH. The stability
of polyphenol oxidase (PPO) extracted from Solanum melongenas and Musa sapientum fruits preincubated
in varying thermal and pH conditions were carried out. Enzyme activity was measured by
spectrophotometric methods. The reaction mixture contained 3.5 mL of 0.20 M phosphate buffer (pH =
6.8), 1.0 mL of 0.75 mM catechol, and 0.5 mL of enzyme solution. PPOS. melongenas and PPOM. sapientum gave
different temperature and pH optima. The temperature-activity profile of PPOS. melongenas and PPOM. sapientum
showed a strong positive correlation (r = 0.907363). At pH = 10.0, PPOM. sapientum activity represented
65.3% decay in enzyme activity, whereas PPOS. melongenas represented 79.3% decay in enzyme activity.
PPOS.melongenas and PPOM. sapientum stability at pre-incubated temperatures of 20, 50 and 60°C and pH
values of 3.5, 6.0 and 8.0 were measured. Residual activities of PPOS.melongenas and PPOM. sapientum showed
a strong positive correlations under the same experimental thermal conditions, with exception at 20°C
(r = 0.693375). Specifically, pre-incubation of PPOM.sapientum for t = 90 min at 60°C caused 18.4% decay in
relative activity of PPOM. sapientum. At t = 90 min, pre-incubation of PPOM. sapientum, at pH = 3.5 caused decay
in activity within the range of 30.8-36.1%, whereas PPOM. sapientum pre-incubated in pH = 6.0 and pH = 8.0
gave decay in activity within the range of (1.5-9.8%) and (2.7-6.5%) respectively. PPOS.melongenas and
PPOM. sapientum showed relatively higher stabilities as the incubation pH tended towards alkaline
conditions, whereas the two experimental temperatures (20 and 60°C) promoted destabilization.

Strain selections of Russet Norkotah have been selected for enhanced vigor and high yield. In addition, they exhibit less severe expression of disease symptoms in the presence of Verticillium dahliae, a soil-borne fungal pathogen that causes Verticillium wilt. However, this apparent resistance may be due to later maturity in the strain selections. This study was designed to compare the levels

Catharanthus roseus (L.) G. Don yields anticancer alkaloids, viz. vinblastine and vincristine, in its leaves. Gamma irradiated sodium alginate (ISA) encourages the plant growth as well as production of alkaloids and other active constituents in different medicinal and aromatic plants (MAPs). Methyl jasmonate (MeJA) is a potent elicitor of secondary metabolites in plants, especially under adverse environmental conditions. In view of these considerations, three pot-experiments were conducted in the net house according to simple randomized design in order to reveal the effect of foliar application of ISA and MeJA (potent elicitors) and of their combinations on growth, physiological attributes and content and yield of total as well as anticancer alkaloids of Catharanthus roseus. Foliar spray of ISA and MeJA, applied alone as well as in combination, resulted in significant improvement in most of the parameters studied. Combined application of ISA and MeJA exerted most favourable effect on the parameters studied, enhancing the total leaf-alkaloids yield by 71.48 and 57.32%, leaf-vincristine yield by 44.53 and 37.82% and, leaf-vinblastine yield by 33.93 and 26.24% at 6 and 9 months after sowing, respectively, in comparison to the control.

Climate change has great impact on agro-ecosystems affecting crop productivity that eventually leads to the problems of food availability. In the Philippines the demands for food supplied by agricultural crops has increased and crop production cannot meet with these demands. In ode to improving crop production to meet the increasing demands for food supply along with the aim of validating the relationship of tillage, presence and absence weeds and soil type to corn growth, this study was conducted. This study determines the set of conditions that promotes optimum germination rate, growth and biomass accumulation of Zea mays. Specifically, it aims to identify existing competition between weeds and Zea mays and whether the type of soil and tillage an important factor in rate of germination, growth in terms of height and biomass accumulation of corn. Setups were identified and treated with different conditions in accordance to their labels. Results showed that germination rate, plant growth (height) and biomass accumulation in terms of fresh weight of Zea mays is highest in an untilled-loamy soil planted with the presence of the weed Cyperus esculentus.

New insights into the phenomenon of systemic acquired resistance have been gained in recent years, by the use of techniques in molecular genetics and biology that have replaced the largely descriptive approach of earlier work. The isolation of mutants in the signal transduction pathway from induction to expression of resistance as well as the use of transgenic plants over-expressing or suppressing the expression of putative candidate genes involved in systemic acquired resistance and its signalling have identified several steps in the establishment of plant resistance. In this review the latest developments implicating salicylic acid as a signal molecule in systemic resistance are discussed and contrasted with new signalling pathways which, seemingly, are based on alternative mechanisms.

Bu çalışmada humik asidin (50, 100, 200, 400 ve 600 ppm) mısır (Zea mays L. cv. 3167) bitkisinde tohum çimlenmesi ve erken fide evresindeki etkileri araştırılmıştır. 50 ve 100 ppm'lik humik asit uygulamaları mısır tohumlarının çimlenmesi üzerinde inhibitör etki yapmazken, 200 ve 400 ppm'lik humik asit çimlenmeyi % 2, 600 ppm'lik humik asit ise % 4 oranında inhibe etmiştir. Uygulanan humik asit konsantrasyonları mısır fidelerinde kök ve gövde büyümesi üzerinde istatistiksel olarak önemli bir değişime neden olmamıştır (P>0.05). Buna rağmen, mısır fidelerinin taze ve kuru ağırlıklarının sadece 200, 400 ve 600 ppm'lik humik asit uygulamaları sonucu kontrole göre önemli derecede arttığı belirlenmiştir (P<0.05). Yapraklardaki fotosentetik pigment miktarı humik asit uygulamaları sonucu önemli derecede azalırken, çözünür protein miktarı artmıştır. 400 ve 600 ppm'lik humik asit mısır yapraklarındaki süperoksid dismutaz (SOD) aktivitesinin önemli derecede azalmasına neden olmuştur. Bu sonuçlara göre potasyum humat etkileriyle bitki gelişimi arasında yakın bir etkileşim olduğu, özellikle de fotosentetik pigment ve protein metabolizmasının etkilendiği söylenebilir. Ancak bu değişimlerin potasyum humatın besleyici özelliğinden mi yoksa bitkilerdeki biyokimyasal ve moleküler yollar üzerindeki direkt etkisinden mi kaynaklandığını açıklamak için farklı çalışmalara ihtiyaç vardır.
ABSTRACT
In this study, the effect of potassium humate (50, 100, 200, 400 ve 600 mg L-1) on seed germination and seedling growth of maize (Zea mays L. cv. 3167) was investigated. Seed germination of maize was not affected by 50 ve 100 mg L-1

Seedlings of Sinapis alba L. species (white/yellow mustard) were grown in nutrient solution containing different concentrations 50, 100, 250 and 500 mg/kg Cu for 10 days. Seedlings were measured and weighed at the end of the experiment. Leaf pigment concentration (chlorophylls a and b and carotenoids), tissular copper concentration and Biological Accumulation Coefficients (BAC) were determined. Copper content in Sinapis alba L. tissues reached 74.54-171.20 mg/kg dry mass, with highest values at high ambient concentration. BAC reached 1.49 at 50 mg/kg and was subunitary at higher concentrations, between 0.75-0.34. Shoot length and biomass emphasize a significant decrease at high ambient copper levels, while photosynthetic pigment concentrations did not decrease. These results indicate a limited tolerance of white mustard to high copper concentrations and a limited bioaccumulation potential of this metal.

Penyakit gugur daun Pestalotiopsis
(PGDP) mengalami outbreak dengan luas
serangan di Indonesia mencapai 382.000 ha
pada tahun 2019. Akibatnya, penurunan
produksi karet lebih dari 30%. Hingga saat
ini, cara yang efektif untuk pengendalian
penyakit ini belum dilaporkan. Upaya
pengendalian penyakit dapat dilakukan
dengan meningkatkan sistem pertahanan
tanaman dan menekan jumlah inokulum di
perkebunan. Penelitian ini bertujuan untuk
mengetahui pengaruh aplikasi pupuk dan
fungisida terhadap kerapatan tajuk dan
penambahan produksi pada klon GT 1 yang
t e r s e r a n g P G D P e s t a l o ti o p s i s .
Dibandingkan kontrol, pemupukan 100%
dosis rekomendasi meningkatkan kerapatan
tajuk 4% dengan kenaikan produksi 3
g/p/s. Pemberian ekstra 25% Nitrogen dan
ekstra Kalium dapat memicu kerapatan
tajuk berturut-turut 5% dan 6% dengan
kenaikan produksi 5 dan 6 g/p/s. Kerapatan
tajuk terbukti meningkat baik dengan
penyemprotan fungisida di gawangan
maupun pengasapan pada daun muda
masing-masing 9%, dan diiringi kenaikan
produksi berturut-turut 5 g/p/s. Kombinasi
aplikasi pupuk ektra 25% N, K dan fungisida
pada gawangan dan fogging memberikan
kerapatan tajuk 9% dan kenaikan produksi
10 g/p/s. Pemupukan berperan dalam
meningkatkan tajuk dan produksi. Aplikasi
fungisida di gawangan dan fogging dapat
mempertahankan tajuk lebih baik dan
produksi karet kering.

Since the 1930's the plant growth regulator Indole-3-butyric acid (IBA) has been used for rooting of plant cuttings and other growth processes. Thousands of articles have been written on it as the favorite single compound used to promote rooting. Uses for IBA other than rooting include promoting root regeneration when transplanting rooted plants and to improve grafting. Useful compounds containing IBA are solutions and powders. Solutions of IBA dissolved in water are useful for more purposes than any other compound.

Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and water, plant hormonal functions, and vital metabolic pathways. Few studies are available on the application of combined nanomaterials to mitigate salinity stress on potato plants (Solanum tuberosum L. cv. Diamont). In order to assess the effects of the sole or combined application of silicon (Si) and potassium (K) nanoparticles and biochar (Bc) on the agro-physiological properties and biochemical constituents of potato plants grown in saline soil, two open-field experiments were executed on a randomized complete block design (RCBD), with five replicates. The results show that the biochar application and nanoelements (n-K and n-Si) significantly improved the plant heights, the fresh and dry plant biomasses, the numbers of stems/plant, the leaf relat...

A. altissima [(M ill.) Swingle] is a hardy, fast-growing, invasive species, common in all temperate areas. The Cu, M n and Zn content was determined in A. altissima individuals growing in the coastal area in Constanța, Romania, as part of a wider screening for local plant species capable of high heavy metal bioaccumulation-with possible application in soil bioremediation. Determination was done through atomic absorption spectrometry of aboveground organ samples, together to corresponding soil samples. The Biological Accumulation Coefficients (BAC)-ratio of metal content in plant organs and soil-were also calculated for each metal. Average metal content was 14.15 mg/kg Cu (above the average value found in normal vegetation), 47.09 mg/kg M n and 36.06 mg/kg Zn (both below average), compared to 42.93 mg/kg Cu, 396.87 mg/kg M n and 166.38 mg/kg Zn average concentrations in adjacent soils. Notable differences were found among different individuals. All tissular metal concentration values were all below accepted thresholds for hyperaccumulation. Average BAC values were 0.43 for Cu, 0.13 for M n and 0.37 for Zn. Higher metal concentration in soils led to lower BAC for all three metals. In conclusion, A. altissima cannot be considered as an accumulating species for selected metals. However, there is a possible potential for copper phytostabilization.