Root Dry Matter Research Articles

Optimal Substrate Moisture Content for Kiwifruit (Actinidia valvata Dunn) Seedling Growth Based on Analyses of Biomass, Antioxidant Defense, and Photosynthetic Response

The fruits of kiwifruit are well known for their abundant nutritional value and health benefits, but kiwifruit vines are susceptible to environmental factors such as drought or waterlogging. Optimum substrate moisture content (SMC) can decrease cultivation costs and improve the quality of seedlings in soilless cultivation. To quantify the water requirements of kiwifruit seedlings, a greenhouse study was conducted to investigate the growth, antioxidant defense, and photosynthetic parameters of seedlings of Actinidia valvata Dunn at six levels of SMC (20%, 40%, 60%, 80%, 100%, and 120%). Results showed that shoot and root dry matter accumulation increased gradually with the increase in SMC from 20% to 100% and was lower at 120% SMC than at 100% SMC. Electrolyte leakage and malondialdehyde content were the lowest at 80% and 100% SMC. Antioxidant enzyme activities, including superoxide dismutase, peroxidase, and catalase, chlorophyll content, net photosynthetic rate, maximal quantum yield of PSII photochemistry, photosynthetic electron transfer rate, and actual quantum yield were the highest at 80% and 100% SMC, but there was no significant difference in these parameters between the two treatments (80% and 100% SMC). However, the shoot and root dry weights of seedlings at 100% SMC were 13.20% and 33.02% higher than those at 80% SMC, respectively. In summary, 100% SMC provided optimal water supply for the photosynthetic efficiency and dry matter accumulation of shoots and roots. The results are expected to be useful for the mass production of high-quality kiwifruit seedlings in greenhouse or nursery containers, with the potential to save water.

Growth and development of yerba mate seedlings associated with different winter cover species

The lack of knowledge of management in the application of yerba mate is the reason for the present study, given the economic importance of this crop for family farming, the economy and also the culture in the southern region of Brazil. The objective of this work was to evaluate the effects of winter cover species on the morphophysiological characteristics of yerba mate seedlings. The experimental design was laid out in randomized blocks with four replicates. The weed species used were Avena strigosa, Lolium multiflorum, Vicia sativa, Raphanus sativus, Lupinus albus, Axonopus catharinensis, the consortium between A. strigosa and V. sativa, and the control treatment without cover. Physiological (photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, water use efficiency, carboxylative efficiency, and chlorophyll) and morphological (plant height, stem diameter, leaf area, shoot and of root dry matter, in addition to cover dry matter) were evaluated. There was competition between the crop and the cover plants for the factors of light and water, and the control without cultivation did not affect the morphophysiological characteristics of yerba mate. The species A. catharinensis proved to be the best cover plant because it competed less with yerba mate. The growth and development of yerba mate were affected by the presence of A. strigosa.

Species phylogeny, ecology, and root traits as predictors of root exudate composition.

Root traits including root exudates are key factors affecting plant interactions with soil and thus play an important role in determining ecosystem processes. The drivers of their variation, however, remain poorly understood. We determined the relative importance of phylogeny and species ecology in determining root traits and analyzed the extent to which root exudate composition can be predicted by other root traits. We measured different root morphological and biochemical traits (including exudate profiles) of 65 plant species grown in a controlled system. We tested phylogenetic conservatism in traits and disentangled the individual and overlapping effects of phylogeny and species ecology on traits. We also predicted root exudate composition using other root traits. Phylogenetic signal differed greatly among root traits, with the strongest signal in phenol content in plant tissues. Interspecific variation in root traits was partly explained by species ecology, but phylogeny was more important in most cases. Species exudate composition could be partly predicted by specific root length, root dry matter content, root biomass, and root diameter, but a large part of variation remained unexplained. In conclusion, root exudation cannot be easily predicted based on other root traits and more comparative data on root exudation are needed to understand their diversity.

Influence of Different Protected Environments and Reflector Material on Cultivated Oiti (Licania tomentosa[Benth.] Fritsch) Seedlings

Abstract Background Oiti (Licania tomentosa[Benth.] Fritsch) is an option for urban forestation and rural environments that require shading by plants, so studying the plant environment to obtain quality seedlings is essential. The present study aimed to evaluate oiti seedlings in different protected environments with or without reflective material on a cultivation bench. Methods The following protected environments were evaluated: an agricultural greenhouse covered with a low-density polyethylene film and a thermo-reflective screen with 42%/50% shading under the film; an agricultural screenhouse with an aluminized screen with 35% shading; an agricultural screenhouse with a black screen with 30% shading; and an agricultural screenhouse with a black screen with 18% shading. Production systems with and without photosynthetically active radiation-reflecting material (aluminized screen, Aluminet®) on the cultivation bench were assessed in each protected environment. Results There was no interaction between the environmental factors; however, the environments influenced height, stem diameter, root dry matter, and total biometric relationships and growth rates. The reflective material did not improve the quality of oiti seedlings. The ratio of shoot and root dry matter was, on average, 71% for the shoots and 29% for the roots. The photosynthetically active radiation received by oiti seedlings ranged from 600 to 1,100 μmol m−2s−1. Conclusions The greenhouse with 42%/50% shading screen under the film and the black screen with 30% shading were the best environments for the formation ofLicania tomentosaseedlings. The reflective material on the cultivation bench did not result in better quality oiti seedlings.

Genotype × Environment Interaction and Stability Analysis of Selected Cassava Cultivars in South Africa

Cassava (Manihot esculenta Crantz) is an important root crop worldwide. It is adapted to a wide range of environmental conditions, exhibiting differential genotypic responses to varying environmental conditions. The objectives of this study were: (1) to examine the effect of genotype, environment and genotype × environment interaction (GEI) on fresh root yield (FRY) and dry matter content (DMC); and (2) to identify superior genotypes that exhibit high performance for the traits of interest using the genetic tools of additive main effects and multiplicative interaction (AMMI) and genotype stability index (GSI) analysis. Eleven cassava genotypes were evaluated in a randomized complete block design at six trial sites in South Africa. The combined analysis of variance based on AMMI revealed significant genotype, environment and GEI for the traits. The percentage variation due to GEI was higher than the percentage variation due to genotype for FRY, reflecting differential genotypic responses across the experimental sites. The proportion of variance due to genotype variation was larger for DMC. Genotype stability index (GSI) showed that UKF3 (G6), 98/0002 (G2) and P4/10 (G5) were the highest yielding and most stable genotypes for FRY, and 98/0002 (G1), UKF3 (G6) and UKF9 (G11) were the highest yielding and most stable genotypes for DMC. Cultivars 98/0002 and UKF3 were identified as providing high stability with superior fresh root yield and DMC. These genotypes could be recommended to farmers for food, feed and industrial applications without the need for further breeding. The AMMI-2 model clustered the testing environments into three mega-environments based on the winning genotypes for FRY and DMC. Mabuyeni (KwaZulu-Natal), Shatale (Mpumalanga) and Mandlakazi (Limpopo) would be the best testing sites in future cassava-genotype evaluation and breeding programs. This study provides a baseline for a future study on the GEI of cassava varieties, using a larger set of genotypes, factoring in seasonal variation.

Phosphate solubilizing microorganisms in organomineral fertilizers to increase the productivity of Vigna unguiculata (L.) Walp.

This work aimed to evaluate the interaction between P-solubilizing microorganisms and organomineral fertilizers in order to increase the cowpea nutrition and yield under field conditions. One field trial was carried out in a randomized complete block design arranged in subdivided plots (7 x 3) with four replicates. The organominerals (poultry litter, swine manure, filter cake and soot from chimneys) as well as triple superphosphate (TSP) with and without sulfur and the control treatment (no fertilizer addition), were considered the primary factor. The secondary factor was constituted by inoculation of Bradyrhizobium sp. SEMIA 6462 (Simbiose Nod Caupi®), one P-solubilizing bacteria (MBSF2) as well as no inoculation treatment. The MBSF2 inoculation combined to the soot organomineral increased the shoot length at 50 DAE. The stem diameter, shoot and root dry matter at 50 DAE were increased by Bradyrhizobium spp. inoculation and poultry litter. Also, the stem diameter was increased using filter cake organomineral and both inoculants. The nodules number was also increased by use of that organomineral combined to Bradyrhizobium spp.

Effect of root stimulator (Rootex) and organic nutrient (Siapton 10L) on the growth characteristics of Cupressus arizonica seedlings.

A factorial experiment was carried out in the Directorate of Sarchnar Nursery in Sulaymani / Kurdistan Region-Iraq, using a randomized complete block design (RCBD) with three replications to study the effect of using root stimulator (Rootex) at three levels were (0 )mgL-1, (670)mgL-1 and (1.34) gmL-1 and foliar application with organic nutrients (Siapton 10L) with three concentration on 1st October 2021 as well, which were (0, 1and 2) mlL-1 and there interactions on Cupressus arizonika’s seedlings growth. The data were analyzed using XLSTAT software, and averages were compared according to Duncan Multiple Range. The results showed the superiority of Rootex treatment at the level 1.34 gmL-1 on the studies characteristics (plant height, percentage of N, P, K in the leaves, chlorophyll content in the leaves, Zink and Iron concentration in the leaves, root length, shoot fresh and dry weight, shoot dry matter and root fresh and dry weight). Treating seedlings’ foliar with (Siapton 10L) at the concentration 2mlL-1 showed the superiority in the studies characteristics (plant height, percentage of N, P, and K in leaves, chlorophyll content in the leaves, Zink and Iron concentration in the leaves, root length, shoot fresh and dry weight, shoot dry matter, root fresh and dry weight and root dry matter). The dual interaction of 1.34 gmL-1 of Rootex with 2mlL-1 (Siapton 10L) showed the superiority in the studies characteristics of (plant height, percentage of N, P, and K in leaves, chlorophyll content in the leaves, Zink and Iron’s concentration in leaves, root length, shoot fresh and dry weight, and root fresh and dry weight.

Measurement of Dry Matter and Starch in Modern Cassava Genotypes during Long Harvest Cycles

Starch (ST) is the main determinant of cassava root industrial quality and is routinely quantified using the specific gravity (SG) method, which is simple but lacks precision. This study aimed to estimate the dry matter (DM) and ST content in nine modern cassava genotypes using the SG method and to develop updated empirical equations that relate SG values with DM and ST content. Two field experiments were conducted using a randomized block design with nine genotypes, nine to ten harvest periods, and four replicates. The correlation between root SG and DM was stronger than that between root SG and ST; however, harvest seasonality strongly influenced this relationship. Genotypes varied in their earliness of ST accumulation in the roots, and genotype-specific equations estimated root DM and ST with greater accuracy than equations based on pooled data from all genotypes. Furthermore, the equations from the literature were less accurate in estimating the root DM and ST content than the equations generated in this study. Therefore, these equations can be used by processing industries to improve the predicted cassava root DM and ST content; however, it may be necessary to include the percentage of ST that industries cannot remove from fresh cassava roots during processing.

Biocontrol efficiency of microencapsulated Trichoderma harzianum coupled with organic additives against potato stem rot caused by Sclerotium rolfsii

Potato (Solanum tuberosum L.), world's fourth most carbohydrate supplying crop is often challenged by numerous pathogens among which Sclerotium rolfsii remains one of the most damaging during both growth and storage. As biocontrol is being preferred for their safety and sustainability, the present experiment was conducted for testing the biocontrol effectiveness of microencapsulated Trichoderma harzianum application in combination with organic additives against S. rolfsii. Five combinations (no T. harzianum+no organic additive [control]; T. harzianum+no organic additive; T. harzianum+rice husk biochar; T. harzianum+mustard oil cake; and T. harzianum+tea waste) were tested against two levels of S. rolfsii (absence [control] and presence) under a polyhouse environment. Prior to that, hyper-parasitism of T. harzianum against S. rolfsii was tested in vitro which showed 63.2% growth inhibition for the later. Polyhouse study revealed 16%, 25%, 19%, 21%, 38%, 27%, 9%, 13%, 28%, 20% and 9% average increase in plant height, branch number plant–1, leaf number plant–1, shoot dry matter, root dry matter, healthy tuber, total tuber yield, leaf greenness, net photosynthetic rate, total phenolic content and total antioxidant activity respectively with a subsequent reduction of 49% unhealthy tuber and 32% disease severity index due to T. harzianum+organic additive treatments. Disease suppression and growth recovery of S. rolfsii inoculated potato plants were found significantly better when T. harzianum was applied with organic additives compared to solitary application. The results of this study would provide useful information in strategizing T. harzianum formulation preparation for effective biocontrol of potato stem rot caused by S. rolfsii.

The Combined Application of Biochar and Arbuscular Mycorrhizal Fungi (AMF) Enhanced the Physical and Chemical Properties of Soil and Rice Productivity in Indonesia

Plant productivity, soil quality, and nitrogen uptake can be increased via the combined application of biochar and arbuscular mycorrhizal fungi (AMF). Here, we evaluate the effects of the combination of four different rates of biochar (B) (B0: 0 t ha−1, B1: 20 t ha−1, B2: 40 t ha−1, and B3: 60 t ha−1) and four rates of AMF (M) (M0: 0 g polybag−1, M1: 15 g polybag−1, M2: 30 g polybag−1, and M3: 45 g polybag−1) on the rice (Oryza sativa L.) cultivar Trisakti, grown in polybags using a completely randomized design with three replications. Our results show that the combination of 60 t Biochar ha−1 and 45 g AMF polybag−1 (B3M3) was the best treatment for improving some parameters, such as soil porosity (with the highest values of 68.25 and 68.45%), BD (0.88 and 0.88 g cm−3), pH (6.77 and 6.76), SOM (3.05 and 3.02%), TN (0.48 and 0.47%), AP (31.04 and 31.15 ppm), AK (235.11 and 235.20 ppm), plant height (116.78 and 117 cm), SPAD chlorophyll at maturity stage (43.59 and 43.88), flag leaf area (15.12 and 15.33 cm2), root length (42.10 and 42.17 cm), root volume (53.79 and 53.08 cm3), and shoot dry matter (59.29 and 59.66 g), in the early and late season, respectively. However, the combination of 20 t Biochar ha−1 and 45 g AMF polybag−1 (B1M3) was the best treatment for enhancing the tiller number with the maximum values (52.67 and 53.22), flowering day (67 and 66 day), root dry matter (32.37 and 32.51 g), panicle number (34.67 and 35.21), panicle length (21.44 and 21.67 cm), 1000 grain weight (41.26 and 41.37 g), and nitrogen uptake (32.37 and 32.51 g polybag−1), in the early and late season, respectively. These findings indicate that rice growth and productivity, the physical and chemical soil characteristics, and nitrogen uptake were better with the combined application of biochar and AMF treatments than sole biochar, sole AMF, or the control treatments.

Effects of exogenous strigolactone on growth, dry matter accumulation, and yield of tissue-cultured ginger

ABSTRACT Ginger tissue culture seedlings can reduce the incidence of soil-borne diseases. However, they have several branches, small ginger bulbs, and slow seed recovery. Strigolactone can inhibit the growth of lateral buds, adjust plant types, and increase crop yield. This study used exogenous strigolactone to treat tissue-cultured ginger and assess its effects on growth, dry matter accumulation, and yield. The results showed that the number of branches and ginger bulbs per plant decreased significantly with the application of exogenous GR24 (Synthetic analog of strigolactone, rac-GR24), and higher concentrations led to a greater decrease. Plant height, stem diameter, root, rhizome, stem sheath, leaf and plant dry matter accumulation, average ginger bulb weight, and yield increased significantly, increasing initially and then decreasing with increasing concentration. Depending on the concentrations, exogenous strigolactone can inhibit the branching of tissue-cultured ginger, reduce the number of branches, increase plant height and stem diameter, optimize the aboveground plant type, increase dry matter accumulation and root-shoot ratio, decrease the number of ginger bulbs per plant, increase the average ginger ball weight, and increase yield. When the GR24 concentration was further increased, the number of branches, the plant height, stem diameter, dry matter accumulation, root shoot ratio, ginger bulbs per plant, average weight of ginger bulbs, and ginger yield decreased. Treatment with 7.5 um L−1 of exogenous GR24 could optimize the plant type of tissue-cultured ginger and increase yield.

Ammonium Fertilization Enhances Nutrient Uptake, Specifically Manganese and Zinc, and Growth of Maize in Unlimed and Limed Acidic Sandy Soil

Although NH4+ fertilization is known to acidify rhizosphere and enhance nutrient uptake, the effects on a nutrient-sufficient acidic soil amended with lime are not demonstrated. Thus, the influence of NH4+ fertilization of an unlimed and limed (3 g calcium carbonate per kg soil) acidic soil on the nutrient uptake and growth of maize was studied in comparison to NH4NO3 fertilization. The pH of limed rhizosphere soil was about two units higher than that of the unlimed soil. The maize plants were grown in pots under greenhouse conditions for about two months. The results showed that the pH of the NH4+-fertilized unlimed and limed soil was 0.54 and 0.15 units lower than the NH4NO3-fertilized soil. Liming negatively affected shoot and root dry matter production, whereas the NH4+-fertilized plants produced higher dry matter than the NH4NO3-fertilized plants, with significant difference of 28% in the limed soil only. Liming decreased Fe concentration in rhizosphere soil from 99 to 69 mg kg−1 and decreased plant-available Mn the most (71%), whereas the NH4+-fertilized unlimed and limed soil had 48% and 21% higher Mn concentration than the respective NH4NO3-fertilized soils. Similarly limed rhizosphere soil had 50% lower plant-available Zn concentration than the unlimed soil, and the NH4+-fertilized soil had an 8% higher Zn concentration than the NH4NO3-fertilized unlimed soil. The liming negatively affected P, K, Mn, and Zn concentrations and contents in maize shoot to a lower degree in the NH4+-fertilized soil, whereas the positive effect of NH4+ on the nutrient concentration and contents was vigorous in the unlimed soil than the limed soil. It is concluded that NH4+ fertilization could be beneficial in enhancing nutrient uptake and growth of maize in both acidic and alkaline soils, despite the higher inherent plant-available concentrations of the nutrient in soil.

Physiological effects of some engineered nanomaterials on radish (Raphanus sativus L.) intercropped with pea (Pisum sativum L.).

Intercropping leguminous plant species with non-legume crops could be an effective strategy to maintain soil fertility. Additionally, the application of nano-Zn and Fe in trace amounts can substantially improve the bioavailable fractionof Zn and Fe. We studied the effect of foliar application of some nanomaterials on the agronomic, physio-biochemical attributes under a radish/pea intercropping system. The radish and pea were sprayed with different nanomaterials (Zn-Fe nanocomposite, nZnO, and nanobiochar) at 0 and 50mg L-1 concentrations. Results indicated that the growth parameters of radish were higher in intercropping than in monocropping, while pea growth was inhibited in intercropping compared with monocropping. The shoot and root length, fresh weight, and dry matter of radish were increased by 28-50%, 60-70%, and 50-56% by intercropping than monocropping. Foliar spray of nano-materials further increased the growth traits of intercropped radish, such as shoot and root length, fresh weight, and dry matter, by 7-8%, 27-41%, and 50-60%, respectively. Similarly, pigments such as chlorophyll a, b, and carotenoids and the concentration of free amino acids, soluble sugars, flavonoids, and phenolics were differentially affected by intercropping and nanomaterials. The yield of the non-legume crop was increased by intercropping, whereas the legume crop exhibited significant growth inhibition due to competitive interactions. In conclusion, both intercropping and foliar spray of nanomaterials could be used as a combined approach to benefit plant growth and enhance the bioavailable Fe and Zn fractions of both crops.

English

Immobilization is an efficient method in the remediation of heavy metal-polluted soils. A greenhouse experiment was conducted to investigate the influence of fish scale powder, chitin, and chitosan on the growth and chemical composition of rice grown on a soil contaminated with Zn, Pb, Cd, and Ni. Results showed that the application of fish scale powder, chitin, and chitosan significantly increased root and shoot dry matter yield of rice, but decreased Pb phytoextraction efficiency. Further, the translocation factor of Ni decreased following the application of fish scale powder and chitosan. Application of fish scale powder decreased Ni, Cd, Zn, and Pb bioavailability in soil. The addition of chitosan caused 56% decrease in shoots Ni concentration as compared to control. Among different amendments, only the application of chitosan had a significant effect on the reduction of Zn content in rice root by 70% as compared to control. Considering that the translocation factors were less than one in all treatments, it can be concluded that biostabilization of the studied metals has occurred. Based on the obtained results, fish scale derivatives including fish scale powder and chitosan play an important role in the removal of heavy metals due to having suitable functional groups. Therefore, it can be deduced that due to the economic feasibility, environmentally friendly, and high metal removal capability of chitosan and fish scale powder, these two amendments are highly recommendable to be applied in multi-metal polluted soils for increasing metals removal and hence decreasing their phytotoxicity.

Short-Term Effects of Cover Crops on Soil Physical, Chemical, and Biological Properties in the Southeastern Argentinean Pampas

ABSTRACT Cover crop (CC) inclusion in cropping sequences could ameliorate negative effects of continuous agriculture on soil properties. The use of CC as a sustainable management tool can reverse the soil degradation process and improve soil health in the short term. The present study evaluated soil properties following short-term cover cropping in on-farm conditions. Three strip-trial experiments were conducted. Treatments were: i) oat (Avena sativa), ii) vetch (Vicia villosa), and iii) control (without CC). Prior to CC chemical termination, shoot and root dry matter (DM) and DM nitrogen accumulation in CC shoot (Nac) were determined. After CC termination, we determined: soil bulk density (BD), penetration resistance (PR), infiltration (INF), aggregate stability, total and particulate organic carbon (POC), organic nitrogen, nitrogen mineralized in anaerobic incubation (Nan) and soil glomalin. On average across sites, grater shoot, and root DM were determined in oat than vetch, while Nac was greater in vetch. The POC and Nan increased by CC inclusion mainly in 0–5 cm soil depth. Improvements of over 50% in INF (0–20 cm) and 8% in BD (0–5 cm) were determined in CC treatments compared to control. The effects of CC on some soil parameters depended on the previous management practices (i.e. tillage system, crop sequences). In the short-term, CC inclusion improves some soil properties, depending on their sensibility to management practices.

Comparison of cotton (Gossypium hirsutum) hybrids and their non-transgenic in India

It is still not clear whether differential response of Bt cotton and conventional non-Bt cotton genotypes in terms of growth, phenology and yield ability are hypothetical or realistic. This study investigated the response of three Bt cotton hybrids in comparison to their conventional non-transgenic version (near-isogenic lines) along with two locally adapted genotypes for growth, yield attributes, phenological characteristics and rooting behavior. Therefore, two experiments were conducted during summer season of year 2016 and 2017 to evaluate differences among 3 popular Bt cotton hybrids along with their non-Bt version. First field experiment was conducted as a pot study wherein shoot and root parameters of 3 Bt cotton hybrids (Ankur 3028, MRC 7017, Bioseed 6588) were compared with their non-Bt version along with 2 local checks (i.e.,hirsutum cotton Cv. F2228 and arboreum cottonCv. FDK124). Second field experiment evaluated growth, phenological characteristics, yield attributes and productivity potential of above mentioned Bt and non-Bt hybrids. Findings of pot experiment could not establish any significant difference among studied Bt and non-Bt hybrids for root and shoot characteristics. However, arboreum cotton FDK124 exhibited higher root length than all genotypes. Results of second experiment revealed significant differences for phenological characteristics, wherein Bt version of all the tested hybrids exhibited earliness for flowering initiation, 50 % flowering and days to maturity over their non-Bt version. Seed cotton yield (SCY) in all hybrids possessing Bt gene was significantly higher than their non-Bt version primarily due to higher bolls plant-1. Studies conclude that introgression of Bt gene could not alter rooting parameters of evaluated cotton genotypes but significantly affected phenological stages by inducing earliness and higher SCY in Bt versions due to improved bolls plant-1. Keywords: Bt cotton; Near-isogenic lines; Phenology; Root dry matter; Seed cotton yield

Cotton nitrogen doses in the edaphoclimatical conditions of northeastern Brazil

The study of cotton plant responses to nitrogen fertilization in different climate and soil conditions is essential for the correct management of nitrogen in this crop. Therefore, the objective of the present study was to evaluate the responses of cotton plants to nitrogen fertilization in the edaphoclimatic conditions of the Cariri region, located in the northeastern State of Ceará, Brazil. The experiment was conducted in an experimental area at the CENTEC (Centre for Technological Education) School of Technology (FATEC - Cariri campus), located in the city of Juazeiro do Norte, Ceará State. The statistical design adopted was Completely Randomized Design (CRD). The treatments were composed from the combination of four doses of nitrogen (0, 60, 120, and 180 kg ha-1 of N, equivalent to 0, 50, 100, and 150% of the N recommendation for the crop) with four replications. Urea was used as a nitrogen source. At 42 days after sowing, the plants were collected. Plant height, number of leaves, stem diameter, leaf area, absolute growth rate, shoot and root dry matter, total and nitrogen use efficiency were evaluated. The different doses of nitrogen significantly influenced all the analysed variables. In general, nitrogen doses greater than 120 kg ha-1 of N were shown to impair the growth and dry matter production of the cotton plant in the climate and soil conditions of the Cariri region, northeastern Brazil. In addition, excessive nitrogen fertilization was shown to reduce the efficiency of nitrogen use by the cotton crop.

Lasting effect of Urochloa brizantha on a common bean-wheat-maize rotation in a medium-term no-till system

Grass intercropping under no-till is an option to increase crop residues on the soil surface and crop diversity. Urochloa spp. is frequently selected for intercropping to improve land use and agricultural production because of its high residue production, slow residue decomposition, as well as its vigorous, abundant, and deep root system. However, the effects of intercropping Urochloa and maize, especially the effects of Urochloa residues, on subsequent crops in rotation have not been established. To address this knowledge gap, a field experiment was carried out over 5 years (from 2014 to 2018) comprising 2 years of maize monocropping or intercropping and 3 years of crop rotation (common bean-wheat-common bean-wheat-maize). We evaluated the medium-term effects of monocropped maize or maize intercropped with Urochloa brizantha on soil fertility and the development, yields, and grain nutrient accumulation of subsequent common bean, wheat, and maize crops. The cultivation of U. brizantha in the intercropping system improved soil fertility over at least 4 years, with increases in soil pH; soil organic matter (SOM); phosphorus (P); exchangeable potassium (K), calcium (Ca), and magnesium (Mg); sulfur (S–SO42−); cation exchange capacity (CEC); and base saturation (BS) at all soil depths. The benefits of U. brizantha extended to root dry matter and distribution; 70–77% of the total roots were concentrated within a soil depth of 0.0–0.2 m. The intercropping system improved the root dry matter mass, yield components, and grain yields of subsequent common bean, wheat, and maize crops in all cultivation years. These findings indicate that intercropping maize and U. brizantha provides medium-term benefits for subsequent common bean, wheat, and maize crops, and improves nutrient cycling to increase soil P; exchangeable K, Ca, and Mg; S–SO42−; and organic matter content.

Interaction of liming, mineral nitrogen fertilization, and Rhizobium inoculation in biomass partitioning and production of cowpea

Cowpea has great capacity of biological fixation of nitrogen (BFN) in association with Rhizobium. However, it is not known whether the interaction of liming, mineral N fertilization, and Rhizobium-inoculated seeds can modify the efficiency of BFN, and still, result in gains in biomass production and yield in cowpea. This study evaluated the use of liming associated to Rhizobium-inoculated seeds and supplemental mineral N fertilization on the nodulation improvement, biomass production, and on the increase of cowpea grain production. Two experiments were conducted under field conditions in two consecutive years, using the same treatments and experimental design. The treatments were conditioned in a split-plot scheme in randomized blocks with four replications in a 2 × 6 factorial, the first factor being two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and the second factor was considered six conditions of corrective practice and N supply [no N supply and no liming (T1), liming + rhizobium (T2), rhizobium (T3), liming + mineral N (T4), liming (T5), and liming + mineral N + rhizobium (T6)]. Nitrogen concentration and accumulation in the leaves increased with liming and N supply (T2, T4, and T6) and increased dry matter (DM) accumulation in the stem, leaves, shoots, and total DM. The absence of liming limited root length growth, decreased root DM, and the number and DM of nodules thus limiting grain production. Additionally, N fertilization supplemented with Rhizobium-inoculated seeds did not increase grain production. However, the use of liming and the inoculation of seeds with Rhizobium increased plant performance and improved grain yield of both cowpea cultivars.

Cloning, subcellular localization and expression of phosphate transporter gene HvPT6 of hulless barley.

Deficiency of phosphate (Pi) is one of the main growth-limiting factors for crops. Generally, phosphate transporters play a key role in the uptake of P in the crops. However, current knowledge regarding the molecular mechanism underlying Pi transport is still limited. In this study, a phosphate transporter (PT) gene, designated HvPT6, was isolated from a cDNA library constructed from hulless barley "Kunlun 14." The promoter of HvPT6 showed a large number of elements related to plant hormones. The expression pattern also indicated that HvPT6 was highly induced by low phosphorus, drought, abscisic acid, methyl jasmonate and gibberellin. Phylogenetic tree analysis revealed that HvPT6 belongs to the same subfamily of the major facilitator superfamily as OsPT6 from Oryza sativa. Subcellular localization of HvPT6:GFP using transient expression of Agrobacterium tumefaciens showed the green fluorescent protein signal in the membrane and nucleus of the Nicotiana benthamiana leaves. Overexpressing HvPT6 led to a longer and higher lateral root length and dry matter yield in the transgenic Arabidopsis lines under low Pi conditions, indicating that HvPT6 improves plant tolerance under Pi-deficient conditions. This study will lay a molecular basis for phosphate absorption mechanism in barley and breeding barley with high-efficient phosphate uptake.