Limited Correlation between Expansin Gene Expression and Elongation Growth Rate

The aim of this work was to study the role of the cell wall protein expansin in elongation growth. Expansins increase cell wall extensibility in vitro and are thought to be involved in cell elongation. Here, we studied the regulation of two tomato (Lycopersicon esculentum cv Moneymaker) expansin genes,LeExp2 and LeExp18, in rapidly expanding tissues. LeExp2 was strongly expressed in the elongation zone of hypocotyls and in the faster growing stem part during gravitropic stimulation. LeExp18 expression did not correlate with elongation growth. Exogenous application of hormones showed a substantial auxin-stimulation of LeExp2 mRNA in etiolated hypocotyls and a weaker auxin-stimulation ofLeExp18 mRNA in stem tissue. Analysis of transcript accumulation revealed higher levels of LeExp2 andLeExp18 in light-treated, slow-growing tissue than in dark-treated, rapidly elongating tissue. Expansin protein levels and cell wall extension activities were similar in light- and dark-grown hypocotyl extracts. The results show a strong correlation between expansin gene expression and growth rate, but this correlation is not absolute. We conclude that elongation growth is likely to be controlled by expansin acting in concert with other factors that may limit growth under some physiological conditions.

Growth cone MKK7 mRNA targeting regulates MAP1b-dependent microtubule bundling to control neurite elongation

Local mRNA translation in neurons has been mostly studied during axon guidance and synapse formation but not during initial neurite outgrowth. We performed a genome-wide screen for neurite-enriched mRNAs and identified an mRNA that encodes mitogen-activated protein kinase kinase 7 (MKK7), a MAP kinase kinase (MAPKK) for Jun kinase (JNK). We show that MKK7 mRNA localizes to the growth cone where it has the potential to be translated. MKK7 is then specifically phosphorylated in the neurite shaft, where it is part of a MAP kinase signaling module consisting of dual leucine zipper kinase (DLK), MKK7, and JNK1. This triggers Map1b phosphorylation to regulate microtubule bundling leading to neurite elongation. We propose a model in which MKK7 mRNA localization and translation in the growth cone allows for a mechanism to position JNK signaling in the neurite shaft and to specifically link it to regulation of microtubule bundling. At the same time, this uncouples activated JNK from its functions relevant to nuclear translocation and transcriptional activation.

Anion exchange membrane soil nitrate predicts turfgrass color and yield.

Desirable nitrogen (N) management practices for turfgrass supply sufficient N for high quality turf while limiting excess soil N. Previous studies suggested the potential of anion exchange membranes (AEMs) for predicting turfgrass color, quality, or yield. However, these studies suggested a wide range of critical soil nitrate-nitrogen (NO3-N) values across sample dates. A field experiment, in randomized complete block design with treatments consisting of nine N application rates, was conducted on a mixed species cool-season turfgrass lawn across two growing seasons. Every 2 wk from May to October, turfgrass color was assessed with three different reflectance meters, and soil NO3-N was measured with in situ AEMs. Cate-Nelson models were developed comparing relative reflectance value and yield to AEM desorbed soil NO3-N pooled across all sample dates. These models predicted critical AEM soil NO3-N values from 0. 45 to 1.4 micro g cm-2 d-1. Turf had a low probability of further positive response to AEM soil NO3-N greater than these critical values. These results suggest that soil NO3-N critical values from AEMs may be applicable across sample dates and years and may serve to guide N fertilization to limit excess soil NO3-N.

Effect of Fungicides and Plant Populations on Soybean Disease and Yield

Applications of foliar fungicides on soybeans have been shown to reduce disease pressure and protect yield under the right conditions, especially in environments that have very wet or humid conditions. In the past decade, fungicide use in Iowa has increased. Initially, growers were concerned with the potential threat of soybean rust, which is controlled effectively by foliar fungicides. In Iowa, however, there has not been any case of yield reduction due to soybean rust. New potential purposes for foliar fungicides include “plant health” benefits and the reduction of foliar diseases endemic in Iowa such as Septoria brown spot, Cercospora leaf blight, and frogeye leaf spot. Currently what is not known is how the efficacy of fungicides is affected when agricultural practices change. Our question: How does plant population affect the efficacy of fungicides?

Northwest Iowa On-farm Research Soybean Yield Response to Headline Fungicide

Six years ago the Northwest Iowa On-Farm Research Project was started to cooperate with local farmers to compare crop production methods on a field scale size. Through this project, over 300 replicated comparisons have been done. Beginning in 2012, the Northwest Iowa On-Farm Research project will be recognized as a part of Iowa State University Farmer Assisted Research and Management (FARM) program. This program will also expand to southwest Iowa, north central Iowa, and central Iowa.

Influence of Crop Load on Tree Growth, Yield, and Fruit Quality of Scab Resistant Apples at Harvest

Apple scab, caused by Venturia inaequalis, is a major disease affecting apple production. Breeding programs have developed over 30 releases of scab-resistant cultivars since 1970 with recent ones having much improved quality. Redfree and GoldRush are from a cooperative breeding program involving Purdue, Rutgers, and Illinois universities while Liberty was introduced from the Cornell University breeding program. For these cultivars to gain better acceptance, more information is needed on their cropping capacities and the effect of crop load on fruit quality attributes. Our study was conducted to determine the relationship between increasing crop load on tree growth, fruit size, and fruit quality variables of the three cultivars under Iowa conditions.

Yield Response of Planting Corn in Early April

Corn is planted earlier each year, which is one important component in maximizing grain yield. Earlier planting dates can be attributed to larger farms, less spring tillage, improvements in corn hybrids, improved drainage systems, and better seed treatments. Research conducted at the ISU Northwest Research Farm from 2006 through 2009 showed that the planting window for 98 percent or greater yield potential in northwest Iowa is April 15 to May 9. A 95 percent or greater yield potential can be realized from April 15 to May 18. A study was conducted from 2009 through 2011 at the Northwest Research Farm to determine how corn planted in early April compares with corn planted in the recommended planting window for the area.

On-farm Cooperator Trials 2011: Effect of Extended-duration Row Covers on Muskmelon and Winter Squash on Bacterial Wilt and Yield

Susceptible cucurbit crops are difficult to grow in Iowa because of bacterial wilt, caused by Erwinia tracheiphila. Striped and spotted cucumber beetles transmit bacterial wilt. Other insect pests such as squash vine borer and squash bugs may also have an economic impact on yield, particularly in squash.

Long-term Tillage and Crop Rotation Effects on Yield

Tillage system and crop rotation have a major long-term effect on soil productivity and soil quality components such as soil carbon and other soil physical, biological, and chemical properties. In addition, both tillage and crop rotation have effects on weed and soil disease control. There is a need for well-defined, longterm tillage and crop rotation studies across the different soils and climate conditions in the state. The objective of this study was to evaluate the long-term effects of different tillage systems and crop rotations on soil productivity.

Soybean Yield Response to Rhizobium Inoculation on Converted Grass Pasture

Much of the soybean plant's nitrogen requirement is supplied through nitrogen fixation when atmospheric nitrogen is converted into a usable form for the plant. Nitrogen fixation is critical for producing higher yield in soybean. For nitrogen fixation to occur, nitrogen-fixing bacteria (genus Rhizobium) need to be present in the soil. If soils do not already contain a high population of Rhizobium, these bacteria can be added either as a liquid or granular peat inoculant, or as a peat-based powder. The different forms can be seed applied or used in-furrow.

High Yield of Soybeans Study

The research project was designed to study soybean plant and yield responses to certain products. Soybean producers generally look to maximize profit, and with increased soybean prices, financial returns have been obtained from even smaller yield responses. The project began in 2011 as a two-year study designed to look at the effects of both seed and foliar treatments applied to soybeans.

Enhancing Yield and Biological Nitrogen Fixation of Common Beans

Two studies were conducted at the ISU Horticulture Station to evaluate potential limitations on yield and atmospheric nitrogen fixation by common bean (Phaseolus vulgaris L.). This legume is a food staple for small landholder farm families worldwide. But it has a limited capacity for nitrogen fixation and often yields only a fraction of its genetic potential. In these studies, we examined the dependence of pod filling on current assimilate supply, as well as the potential to improve nitrogen fixation using an inoculant shown to enhance biological nitrogen fixation under stressful conditions.

Yield prediction and inbreeding of maize synthetics generated with lines and single crosses : classic probability

reduce costs and labor associated with predicting the genotypic mean (GM) of a synthetic variety (SV) of maize (Zea mays L.), breeders can develop SVs from L lines and s single crosses (SynL,SC) instead of L+2s lines (SynL). The objective of this work was to derive and study formulae for the inbreeding coefficient (IC) and GM of SynL,SC, SynL, and the SV derived from (L+2s)/2 single crosses (SynSC). All SVs were derived from the same L+2s unrelated lines whose IC is FL, and each parent of a SV was represented by m plants. An a priori probability equation for the IC was used. Important results were: 1) the largest and smallest GMs correspond to SynL and SynL,SC, respectively; 2) the GM predictors with the largest and intermediate precision are those for SynL and SynL,SC, respectively; 3) only when FL=1, or m is large, SynL and SynSC are the same population, but only with SynSC prediction costs and labor undergo the maximum decrease, although its prediction precision is the lowest. To determine the SV to be developed, breeders should also consider the availability of lines, single crosses, manpower and land area; besides budget, target farmers, target environments, etc.

Fruit yield and growth parameters of several Carica papaya L. genotypes in a temperate climate

The aim of this work was to evaluate changes in growth and productivity parameters of different precocious hybrids and a naturalized variety of papaya under both greenhouse and field cultivation in a temperate climate (the center of the province of Santa Fe, Argentina). In view of the aforesaid, the purpose of our research was to identify further genotypes better suited for the cultivation of this species in temperate climates and demonstrate the need for the use of semi-controlled systems to make possible the cultivation of these promising genotypes in middle latitudes. The average yield was 291% higher in greenhouse than in the field. The average productivity for hybrid genotypes compared with the naturalized variety more than doubled in both environments. Considering behavior in height, leaf area index and yield parameters, hybrids H2 (principally), and H4 showed a great adaptation for use in semi-forced systems. The use of greenhouse and short stature papaya hybrids allows its feasible and surely profitable cultivation in non- tropical climates.

Effect of compost and slow-release fertilizers addition on soil biochemistry and yield of maize (Zea mays L.) in Oaxaca, Mexico

The effect of Bokashi (B, a fermented compost), slow-release fertilizers (SRFs) and their combined application on mycorrhizal colonization (MC), soil invertase, cellulase, acid (AcP) and alkaline (AlP) phosphatases activities and maize (Zea mays L.) yield was investigated in terrace (TS) and valley (VS) soils in Oaxaca, Mexico. A complete randomized design, seven fertilizer treatments and four replications were used: unamended control (C); conventional fertilization (90-46-00 NPK) (CF); B; SRF1 (Multigro 6®, 21-14-10 NPK); SRF2 (Multigro 3®, 24-05-14 NPK); B+SRF1; B+SRF2. Highest root colonization percentage: CF in VS, and SRF2 in TS. Highest extraradical mycelium length: B, B+SRF1, CF in VS, and B+SRF1 in TS. In both soils, B increased the spore number. Highest AcP activity: B, SRF2 in VS, and B+SRF1, B+SRF2 in TS. Highest AlP activity: B+SRF1, CF in VS, and C in TS. Highest invertase activity: B+SRF1, SRF2, CF in VS, and B in TS. Grain yield only increased with B in VS. The significant interaction soil type × fertilizer treatment for the majority of the biological soil properties analyzed suggests that MC and soil enzyme activity response to fertilization was influenced by soil type. Bokashi, alone or combined with SRFs improves biological soil fertility in maize fields.