True-to-type micropropagated plants of para rubber (Hevea brasiliensis Müll. Arg.) via somatic embryogenesis

Plant micropropagation via somatic embryogenesis is a powerful technique for rapid mass propagation, especially in para rubber (Hevea brasiliensis Müll. Arg.). However, somaclonal variations are the major limitation of this process. To date, DNA fingerprinting, i.e., RAPD (Randomly Amplified Polymorphic DNA), Star Codon Targeted (SCoT), and SSRs (Simple Sequence Repeats), is one of the most successful technologies to detect the genetic fidelity in the somatic embryos. The aim of present study was to induce somatic embryos from inner integument explants of para rubber cv. ‘RRIM 600’ at different developmental stages and subsequent acclimatization and transplantation (under greenhouse and field conditions) of the propagated seedlings. The genetic stability of the plants derived from somatic embryos was also analysed in comparison to the mother plant using RAPD, SCoT and SSRs markers. Somatic embryos derived from inner integuments of 5-week-old immature seeds after pollination were more efficient than older and younger seeds. In addition, para rubber mother plants cv. ‘RRIM600’ and plants derived from somatic embryogenesis demonstrated the same pattern of DNA fragments, as confirmed by three PCR-based techniques, RAPD, SCoT and SSRs, whereas these in the pattern were different from ‘RRIT 226’, ‘PB 235’, ‘PB 251’, ‘PB 255’ and ‘BMP 24’. Interestingly, T2 plant was found to possess somaclonal variations when compared with mother plant. Based on the results, we confirm that the plants derived from somatic embryogenesis of para rubber cv. ‘RRIM 600’ were true-to-type to that of ‘RRIM 600’ master stock

Regulation of curcuminoids, photosynthetic abilities, total soluble sugar, and rhizome yield traits in two cultivars of turmeric (Curcuma longa) using exogenous foliar paclobutrazol

Paclobutrazol (PBZ) is a member of plant growth retardants, commonly applied for growth regulation, yield improvement, and biotic and abiotic stress alleviation. However, the effects of PBZ on turmeric (Curcuma longa L.; Zingiberaceae), a rhizomatous herb, have not been well established. The objective of this investigation was to gain a better understanding of the effect of PBZ on two different varieties of turmeric plants, ‘Surat Thani’ (‘URT’; high curcuminoids >5% w/w) and ‘Pichit’ (‘PJT’; low curcuminoids <3% w/w). Pseudostem height of cv. ‘PJT’ treated by 340 µM PBZ was significantly decreased by 14.82% over control, whereas it was unchanged in cv. ‘URT’. Interestingly, leaf greenness (SPAD value), maximum quantum yield of PSII (Fv/Fm) and photon yield of PSII (ΦPSII) in cv. ‘PJT’ treated by 340 µM PBZ were significantly elevated by 1.47, 1.28 and 1.23 folds, over control respectively. Net photosynthetic rate (Pn) in cv. ‘PJT’ declined by 38.58% (340 µM PBZ) over control, as a result of low levels of total soluble sugars (TSS; 127.8 mg g-1 DW) in turmeric rhizome. A positive relation between photosynthetic abilities and aerial fresh weight was demonstrated. In addition, a negative relationship between TSS and total curcuminoids was evidently found (R2 = 0.4524). Curcuminoids yield in turmeric rhizomes significantly dropped, depending on the degree of exogenous foliar PBZ applications. In summary, cv. PJT was found to be very sensitive to PBZ application, whereas rhizome yield and growth traits and high amount of curcuminoids were retained in cv. ‘URT’. Plant growth retention in turmeric cv. ‘URT’ using 170 mM PBZ foliar spray without negative effects on rhizome biomass and total curcuminoids content was demonstrated

Above-ground vegetation indices and yield attributes of rice crop using unmanned aerial vehicle combined with ground truth measurements

Rice is an important economic and staple crop in several developing countries. Indica rice cultivars, ‘KDML105’ and ‘RD6’ are clear favourites, popular throughout world for their cooking quality, aroma, flavour, long grain, and soft texture, thus consequently dominate major plantation area in Northeastern region of Thailand. The objective of present study was to validate UAV (unmanned aerial vehicle)-derived information of rice crop traits with ground truthing non-destructive measurements in these rice varieties throughout whole life span under field environment. Plant height of cv. ‘KDML105’ was more than cv. ‘RD6’ for each respective stage. Whereas, number of tillers per clump in ‘KDML105’ exhibited stability at each developmental stage, which was in contrast to ‘RD6’ (increased continuously). Moreover, 1,000 grain weight, total grain weight and aboveground biomass were higher in ‘KDML105’ than in ‘RD6’ by 1.20, 1.82 and 3.82 folds. Four vegetative indices, ExG, EVI2, NDVI and NDRE derived from UAV platform proved out to be excellent parameters to compare KDML105 and RD6, especially in the late vegetative and reproductive developmental stages. Positive relationships between NDVI and NDRE, NDRE and total yield traits, as well as NDVI and aboveground biomass were demonstrated. In contrast, total chlorophyll pigment in cv. ‘RD6’ was higher than in cv. ‘KDML105’ leading to negative correlation with NDVI. ‘KDML105’ reflected rapid adaptation to Northeastern environments, leading to maintenance of plant height and yield components. Vegetation indices derived from UAV platform and ground truth non-destructive data exhibited high correlation. ‘KDML105’ was rapidly adapted to NE environments when compared with ‘RD6’, leading to maintenance of physiological parameters (detecting by UAV), the overall growth performances and yield traits (measuring by ground truth method). This study advocates harnessing and adopting the approach of UAV platform along with ground truthing non-destructive measurements of assessing a species/cultivars performance at broad land-use scale

Influence of Different Encapsulation Types of Arbuscular Mycorrhizal Fungi on Physiological Adaptation and Growth Promotion of Maize (Zea mays L.) Subjected to Water Deficit

Under drought environment, arbuscular mycorrhizal fungi (AMF) can serve as a long-term biofertilizer to sustain the water and nutrient availability for the host plants. A study was conducted to check the effect of AMF and the encapsulations of the AMF and an organic fertilizer (Fer) with alginate (Al-FA) and agar-agar (Ag-FA) on maize (Zea mays L.) in response to water deficit conditions. The maximum quantum efficiency of PS II (Fv/Fm) of the maize inoculated with Al-FA and Ag-FA under the water deficit was recorded to be 0.70 and 0.50, respectively. Shoot and root water content of the Al-FA plants were found to be maintained under the water deficit and were better than Ag-FA. Besides, phosphorus content in the root tissues of the Al-FA plants grown under the water deficit stress was 1.56-folds greater than in the Ag-FA plants, thereby promoting the photosynthetic abilities and plant height in the former case. The study indicated that the Al-FA type of encapsulation may perform better than the Ag-FA in case of maize plants, leading to its better development under water limited conditions

Evaluation of water deficit tolerance in maize genotypes using biochemical, physio-morphological changes and yield traits as multivariate cluster analysis

Drought is an abiotic stress that inhibits plant growth and development and, therefore, declines crop productivity, as seen in maize plant. The aim of this investigation was to identify the candidate maize varieties that can be grown under water limited conditions using physio-morphological and yield attributes. Eight genotypes of maize including ‘Suwan4452’ (drought tolerant) as a positive check, ‘CP301’, ‘CP-DK888’, ‘DK7979’, ‘DK9901’, ‘Pac339’, ‘S7328’, and ‘Suwan5’ were selected as test plants. Physiological, biochemical and morphological characteristics at seedling (24 day after sowing; DAS) and reproductive (80 DAS) developmental stages of plants under 20-day water withholding (WD), and yield traits at harvesting period were analysed. Leaf temperature in each genotype increased with the degree of water deficit stress, leading to leaf chlorosis, and reduction in maximum quantum yield of PSII (Fv/Fm), photon yield of PSII (ΦPSII), net photosynthetic rate (Pn), overall growth and yield. Pn and stomatal conductance (gs) in drought tolerant genotype, ‘Suwan4452’, were decreased by 19.1% and 18.6%, respectively, whereas these in drought sensitive, ‘Pac339’, were significantly declined by 53.9% and 61.8%, respectively. Physio-morphological parameters, growth performance and yield-related traits of maize genotypes grown under water deficit conditions and well-watered conditions were subjected to Ward’s cluster method for identification of water deficit tolerant cultivars. Maintaining photosynthetic abilities, osmotic adjustment and CWSI in drought tolerant genotypes of maize were evidently demonstrated to keep overall growth performance and yield attributes. Based on multivariate cluster analysis and PCA (principal component analysis), ‘Suwan4452’, ‘CP-DK888’ and ‘S7328’ were categorized as drought tolerant genotypes whereas ‘Suwan5’, ‘Pac339’, ‘DK7979’, ‘CP301’ and ‘DK9901’ were identified as drought susceptible cultivars. Hybrid maize cvs. ‘CP-DK888’ and ‘S7328’ may further be suggested to be grown in the rainfed area without irrigation

Regulation of curcuminoids, photosynthetic abilities, total soluble sugar, and rhizome yield traits in two cultivars of turmeric (Curcuma longa) using exogenous foliar paclobutrazol

Paclobutrazol (PBZ) is a member of plant growth retardants, commonly applied for growth regulation, yield improvement, and biotic and abiotic stress alleviation. However, the effects of PBZ on turmeric (Curcuma longa L.; Zingiberaceae), a rhizomatous herb, have not been well established. The objective of this investigation was to gain a better understanding of the effect of PBZ on two different varieties of turmeric plants, ‘Surat Thani’ (‘URT’; high curcuminoids &gt;5% w/w) and ‘Pichit’ (‘PJT’; low curcuminoids &lt;3% w/w). Pseudostem height of cv. ‘PJT’ treated by 340 µM PBZ was significantly decreased by 14.82% over control, whereas it was unchanged in cv. ‘URT’. Interestingly, leaf greenness (SPAD value), maximum quantum yield of PSII (Fv/Fm) and photon yield of PSII (ΦPSII) in cv. ‘PJT’ treated by 340 µM PBZ were significantly elevated by 1.47, 1.28 and 1.23 folds, over control respectively. Net photosynthetic rate (Pn) in cv. ‘PJT’ declined by 38.58% (340 µM PBZ) over control, as a result of low levels of total soluble sugars (TSS; 127.8 mg g-1 DW) in turmeric rhizome. A positive relation between photosynthetic abilities and aerial fresh weight was demonstrated. In addition, a negative relationship between TSS and total curcuminoids was evidently found (R2 = 0.4524). Curcuminoids yield in turmeric rhizomes significantly dropped, depending on the degree of exogenous foliar PBZ applications. In summary, cv. PJT was found to be very sensitive to PBZ application, whereas rhizome yield and growth traits and high amount of curcuminoids were retained in cv. ‘URT’. Plant growth retention in turmeric cv. ‘URT’ using 170 mM PBZ foliar spray without negative effects on rhizome biomass and total curcuminoids content was demonstrated.</jats:p

Exogenous Foliar Application of Glycine Betaine to Alleviate Water Deficit Tolerance in Two Indica Rice Genotypes under Greenhouse Conditions

The aim of this investigation was to enhance overall growth, yield attributes as well as physio-biochemical adaptive strategies by exogenous foliar application of glycine betaine (GlyBet) in two rice varieties against water deficit stress under greenhouse conditions. Rice crop cvs. RD43 (low amylose content) and SPR1 (high amylose content) grown in clay pots containing garden soil until booting stage were chosen as the test plant material, sprayed by 0 (control) or 100 mM GlyBet and subsequently subjected to: MWD (mild water deficit by 8 d water withholding; 24.80% SWC; Soil water content) or SWD (severe water deficit by 14 d water withholding; 13.63% SWC) or WW (well-watered conditions or control). Free proline content in cv. RD43 was rapidly increased in relation to the degree of water deficit and suppressed by exogenous GlyBet, while free proline in cv. SPR1 was lower than cv. RD43. Overall growth performances and yield traits in both cultivars under MWD were maintained by exogenous application of GlyBet; however, these parameters declined under SWD even after the GlyBet application. Degradation of photosynthetic pigments and chlorophyll fluorescence in pretreated GlyBet plants under SWD were prevented, resulting in elevated net photosynthetic rate (Pn). Interestingly, Pn was very sensitive parameter that sharply declined under SWD in both RD43 and SPR1 genotypes. Positive relationships between physio-morphological and biochemical changes in rice genotypes were demonstrated with high correlation co-efficiency. Based on the key results, it is concluded that foliar GlyBet application may play an important role in drought-tolerant enhancement in rice crops.</jats:p