Short-season Production Research Articles

Controlling indeterminacy in short season lentil by cultivar choice and nitrogen management

Western Canada is a major area of lentil (Lens culinaris Medik.) production and global export, specializing in short season production. In cool or wet years lentil often fails to mature within the 115-d growing season. In the absence of a determinate cultivar, our goal was to test whether current cultivars could mature earlier and without a yield penalty by managing N fertility practices. Eight cultivars of lentil were grown in Saskatchewan during 2006 and 2007 under three N fertility treatments: 50kgNha−1, Rhizobium inoculant, and an uninoculated control. Measurements included days to maturity, yield, aboveground biomass (DW), plant total N content, and N2 fixation. Lentil yielded 1900kgha−1, 2120kgha−1 and 2070kgha−1 in control, fertilized, and inoculated treatments, respectively. The N treatments did not affect days to maturity or harvest index (HI). Yield and N2 fixation were unaffected by the N treatments except in drought, where yield was smallest in the control and N2 fixation was smallest in the fertilized treatment. Cultivars CDC Milestone, CDC Red Rider and CDC Rouleau had comparable yield and matured earlier than large-seeded cultivars, demonstrating that growing a recently released small-seeded cultivar gave earlier maturity than N fertility management. Results did not demonstrate any advantage from applying N fertilizer to hasten maturity, to increase HI or yield compared to the current practice of relying on N2 fixation from proper inoculation. Biological N2 fixation is a sustainable and more economical means of supplying N to the lentil crop without the need to apply N fertilizer, particularly with high yielding early maturing cultivars.

Evaluation of tomato ( Lycopersicon esculentum L.) variety tolerance to foliar diseases at Kenya Agricultural Research Institute Centre-Kitale in North west Kenya

Most vegetable cultivar evaluation trials focus on yield and quality attributes. However, disease tolerance is not routinely evaluated along with other parameters. The objective of this study was to evaluate new tomato cultivar for yield, quality and tolerance to foliar diseases. The most ubiquitous and devastating pathogen that infects tomatoes in the North rift Kenya is Phytophthora infestans that causes late blight and Alternaria solanithat causes early blight. There are several disease management practices that can be implemented to manage this disease including rotation, mulching, spacing, fungicide applications, and use of tolerant varieties. This study aimed at testing different varieties. Six new tomato cultivars, TKA143-33, TKA158-6, TKA193-28, TKA155-18, TKA193-2, TKA195-43 alongside a local check, CALJ were evaluated. The trial was laid out in completely randomized Block design (RCBD) layout replicated four times. The results showed that there were significant differences among varieties during the long season but not short rain season on yield. The local check CAL-J gave the least yield. There was low incidence of foliar diseases on the newly introduced varieties. This suggests that some of the new varieties could be good candidates for long and short season production seasons. Key words: Tomato, variety, on-station trial, disease tolerance, evaluation Kenya.

US effort in the development of new crops (Lesquerella, Pennycress Coriander and Cuphea)

The US effort for the development of new crops is directed toward the advancement of crops that can be grown in rotation with traditional commodity crops, off-season production and utilization of acreage not currently under cultivation. This effort is intended to have no or minimal impact on crop rotations that are sources for food production. The high oil content and the fatty acid profiles of mustard crops make them suitable for utilization as both fuels and base stocks for functionalized industrial chemicals. Pennycress (thlaspi arvense) and lesquerella (lesquerella fendleri) are representatives of this family and have received much attention due to their potential to grow over winter in rotation with soybean production throughout the Midwest (pennycress) or as a winter annual in the desert southwest (lesquerella). Pennycress is an oilseed crop that produces 36% oil with a wide distribution of fatty acids (principal fatty acid is erucic acid 37%) that make it suitable for production of biodiesel. The key aspect of pennycress is that its lifecycle is complete such that a full season soybean can follow its production in the same growing season. Lesquerella is an oilseed crop containing 30% oil that is composed of 60% hydroxy fatty acids. Hydroxy fatty acids are used in a wide range of industrial and cosmetic applications. Two other New Crops currently under investigation are cuphea and coriander. Cuphea is an oilseed crop that contains 35% oil that is composed of medium chain saturated fatty acids. The current cuphea variety under investigation is high in capric fatty acid (76%) with other cuphea species producing high levels of lauric acid. Cuphea can be grown throughout the Midwest but suffers from several agronomic traits that are currently limiting is potential adaptation. Coriander is also an oilseed crop with 25% oil where the main fatty acid is petroselinic acid (76%). Coriander can be grown under a short season production and has potential to rotate as a second crop following winter wheat. Petroselinic acid can be ozonolytically cleaved into adipic and lauric acids both high volume industrial chemicals.

Climate change: Can wheat beat the heat?

Climate change could strongly affect the wheat crop that accounts for 21% of food and 200 million hectares of farmland worldwide. This article reviews some of the approaches for addressing the expected effects that climate change may likely inflict on wheat in some of the most important wheat growing areas, namely germplasm adaptation, system management, and mitigation. Future climate scenarios suggest that global warming may be beneficial for the wheat crop in some regions, but could reduce productivity in zones where optimal temperatures already exist. For example, by 2050, as a result of possible climate shifts in the Indo-Gangetic Plains (IGPs) – currently part of the favorable, high potential, irrigated, low rainfall mega-environment, which accounts for 15% of global wheat production – as much as 51% of its area might be reclassified as a heat-stressed, irrigated, short-season production mega-environment. This shift would also represent a significant reduction in wheat yields, unless appropriate cultivars and crop management practices were offered to and adopted by South Asian farmers. Under the same climate scenarios, the area covered by the cool, temperate wheat mega-environment could expand as far as 65°N in both North America and Eurasia. To adapt and mitigate the climate change effects on wheat supplies for the poor, germplasm scientists and agronomists are developing heat-tolerant wheat germplasm, as well as cultivars better adapted to conservation agriculture. Encouraging results include identifying sources of alleles for heat tolerance and their introgression into breeding populations through conventional methods and biotechnology. Likewise, agronomists and extension agents are aiming to cut CO 2 emissions by reducing tillage and the burning of crop residues. Mitigation research promises to reduce emissions of nitrous oxide by using infrared sensors and the normalized differential vegetative index (NDVI) that determines the right times and correct amounts of fertilizer to apply. Wheat geneticists and physiologists are also assessing wild relatives of wheat as potential sources of genes with inhibitory effects on soil nitrification. Through the existing global and regional research-for-development networks featuring wheat, technology and knowledge can flow to allow farmers to face the risks associated with climate change.

Barley leaf rust (Puccinia hordei Otth) in three production systems and practices in Ethiopia

To determine the prevalence, incidence and severity of leaf rust (Puccinia hordei) in three different production systems of Ethiopia, 276 barley (Hordeum vulgare) fields from the main rainy season (MRS), residual moisture season (RMS), and short rainy season (SRS) production systems were surveyed during the 2003 and 2004 cropping seasons. Over the 2 years, all the barley fields in RMS, 93% in MRS and 51% in SRS production systems were affected by leaf rust. Mean incidence of leaf rust varied from 34.8% in SRS to 76.4% in RMS and in the same order severity of the disease varied from 5.9 to 15.3%. The mean differences in incidence and severity within the variable classes for the provinces, districts, altitude, fertilizer application, weed density and local cultivar were also high. The independent variables: production systems, provinces, districts, altitude, planting dates, fertilizer application, local cultivar and weed density were significantly associated with high incidence and severity of leaf rust as single predictors in the logistic regression models. However, region and slope of a barley field were not associated with increasing disease intensity. A reduced multiple variable model was fitted using districts, altitudes, fertilizer applications, and weed densities as independent variables. Low rust incidence (⩽50%) and severity (⩽5%) had a high probability of association to Enessie, Agew Midir, Degem and Ankober districts. Incidence of above 50% and severity of above 5% had high probability of association to the RMS production system, Gassera district, and high weed density. In the reduced multiple variable models, province and local cultivar lost importance due to the confounding effect with the districts.

STRAWBERRY NURSERIES: SUMMARIES OF ALTERNATIVES AND TRIALS IN DIFFERENT GEOGRAPHIC REGIONS

STRAWBERRY NURSERIES: SUMMARIES OF ALTERNATIVES AND TRIALS IN DIFFERENT GEOGRAPHIC REGIONS

Bradyrhizobium japonicum Mutants Allowing Improved Soybean Yield in Short Season Areas with Cool Spring Soil Temperatures

In short-season production areas, cool soil temperature is a major factor potentially limiting soybean [Glycine max (L.) Merr.] plant growth and yield. Genistein (4′,5,7-trihydroxyisoflavone) is a signal compound secreted from soybean roots and is essential to establishment of the soybean–Bradyrhizobium japonicum N-fixing symbiosis. The addition of genistein to soybean inocula has proven to be an effective means of generating increases in N fixation and yield; however, genistein is costly. We used ultraviolet (UV) mutagenesis to make 10 mutants of USDA 110 that express the nod genes without exposure to genistein. A field experiment was conducted at the Lods Agronomy Research Centre in southwestern Quebec in 1998 and 1999. The treatments consisted of factorial combinations of inoculant type [no inoculant (control) and inoculants containing the mutants or the wildtypes 532 C or USDA 110] and soybean cultivar (OAC Bayfield and Maple Glen). Inoculation with mutant strains Bj 30055 and Bj 30058 resulted in greater soybean yields than inoculation with 532 C (6.2% increase, averaged across the 2 yr) or the wildtype USDA 110 (9.9% increase, averaged across the 2 yr). These increases were largely due to increases in pod and seed number. These results showed that mutants that express nod genes in the absence of plant-to-bacteria signal compounds can help to overcome the low temperature limitation of soybean nodulation leading to improved growth and yield of soybean crops grown in areas with cool spring soils.

Optimizing Soybean Plant Population for a Short-Season Production System in the Southern USA

Soybean [Glycine max (L.) Merr.] production systems that utilize short-season cultivars for double cropping and late sowing often have insufficient time to establish a complete canopy prior to reproductive development. Our objectives were to evaluate plant population as a tool to manage crop growth, maximum biomass (BM), the time required for canopy closure, and yield. Field tests were sown on 8 July 1997 and 26 June 1998 at Keiser, AR (35 degrees 67' N, 90 degrees 83' W) in 0.19-, 0.57-, and 0.95-m rows with maturity group IV soybean cultivars Asgrow 4922 (A4922) and Manokin. Yield from irrigated and nonirrigated treatments increased as population density increased from 7 to 134 plants m-2, except when lodging occurred. Populations recommended for early-season sowing (25-35 plants m-2) resulted in many plots not achieving 90% light interception (LI), especially in 1998 when weather was hotter and drier than in 1997. The time required after emergence to begin linear crop growth (t(b)) was dependent on LI, and as density increased, t(b) decreased. The values of t(b) varied from 16 to 27 d in 1997 and 22 to 37 d in 1998, with up to 12 d difference in achieving >90% LI. In this short-season production system, yield, crop growth rate between R1 and R5, BM, and t(b) were dependent upon the early establishment of a high LI. Losses attributable to excessive delays in canopy establishment and slow crop growth could be minimized by using high populations in narrow rows. Our research indicates that higher populations than are traditionally recommended provide a way to optimize grain yields in time-constrained systems.

Application of gibberellic acid to the surface of soybean seed (t Glycine max (L.) Merr.) and symbiotic nodulation, plant development, final grain and protein yield under short season conditions

In short-season soybean production areas, low soil temperature is the major factor limiting soybean establishment, nodulation and nitrogen fixation. Gibberellic acid (GA) pretreatment of crop seeds can overcome low soil temperature inhibition of seed germination and seedling development. However, previous studies have found that the application of GAs decreased legume nodulation and nitrogen fixation under optimal growth conditions. A field experiment was conducted under short season conditions in eastern Canada to determine whether the application of GA3 to soybean seed could accelerate germination, and increase plant nodulation and nitrogen fixation. The results indicated that GA3 application accelerated seedling emergence but decreased plant nodulation and nitrogen accumulation at early plant growth stages. However, these initial negative effects were overcome as the plants developed. Gibberellic acid applied to soybean seed at the time of planting did not influence final grain and protein yield.

Inclusion of plant structure and fiber quality into a distributed delay cotton model to improve management and optimize profit

Abstract This research introduces a simple variation of distributed delay algorithms to solve some relevant problems in simulation of plant development. Cotton was used as a case study. An energy-based model of cotton plant growth was expanded to account for production of fruit at different main-stem nodes and fruiting branch positions. The inclusion of plant structure in a simulation model permitted more accurate estimation of projected harvest value. The implications to crop and pest management are two-fold. Higher levels of resolution in the plant structure can result in improved estimates of crop value and insect economic injury levels. More explicit representation of plant structure provides a more natural framework for integrated insect models based on organism behavior such as location and fruit size preference. An algorithm is presented to enhance the resolution of ecological applications that include developmental variability. The effects of cotton plant structure on cotton lint yield and fiber quality were determined for a short-season cultivar, TAMCOT CD3H. An existing cotton plant model, COTSIM, was used and adapted to short-season production. The cotton plant model was modified to include plant architecture. Fiber quality parameters and yield of fruit at different branch positions were determined for the test cultivar. Arrays corresponding to different fruiting branch positions and fiber property trends were constructed to better corresponde with patterns observed in field data. These patterns showed that fiber properties are closely associated with the positions on a fruiting branch. The development of fruit position-cohorts was modeled using an algorithm that simulates the distribution of growth rates with a time-distributed delay. This algorithm was extended to include arrays to represent fruit produced at different fruiting branch positions on the plant. The model predicted observed fruiting data from non-stressed plants well. The inclusion of the effects of plant structure on cotton yield and fiber quality permitted a more accurate determination of cotton prices. In addition, when linked to insect pest models, this model will simulate a dynamic, position-dependent effect of insect damage on fruiting structures and economic loss.

Effect of Cotton Defoliants on Leaf Abscission, Immature Bolls, and Lint Yields in a Short-Season Production System

Pink bolloworm (Pectinophora gossypiella Saunders), and associated secondary insect pests have dramatically reduced cotton (Gossypium hirsutum L.) production in the Imperial Valley of California, resulting in mandated short-season cotton production practices. Application of a a chemical defoliant and/or a growth regulator in August or September is an important component of the short-season system. Studies were conducted to determine the effectiveness of various chemical defoliants on cotton lint yield, leaf abscission, and reduction of late-season fruiting forms under a short-season production system in the Imperial Valley (...)

RELATIONSHIP BETWEEN PERCENTAGE EMERGENCE AND GROWING DEGREE DAYS FOR CORN

Seed bed temperature is often the limiting environmental factor affecting corn (Zea mays L.) emergence, particularly in short-season production areas or when conservation tillage practices are employed. In this study, observations of the percentage emergence and seed bed growing degree days (base 10 °C) are used to assess functions which model the emergence response to temperature. Key words: Percentage emergence, growing degree days, log transformation, logistic function

PREDICTION OF SOIL TEMPERATURE FROM AIR TEMPERATURE FOR ESTIMATING CORN EMERGENCE

The soil thermal environment is critical to corn (Zea mays L.) emergence in short-season production areas. A field study was therefore carried out during the emergence period to test a method to predict 0.05-m soil temperatures from air temperatures and to develop a method to quantify emergence rates as a function of actual and predicted soil thermal units. Thermal units (base 10 °C) were calculated from hourly air and measured and predicted 0.05-m soil temperatures; these thermal units were fit to test emergence data collected on six cultivars. The nonlinear response of percentage emergence to thermal units was approximated by an exponential function. Comparisons of cultivar emergence rates, expressed as the number of thermal units to 0 and 75% emergence, statistically differentiated (P ≤ 0.05) the test cultivars into three main groupings. When predicted soil temperatures were used to calculate the number of thermal units, the thermal units to specific emergence levels were within the equivalent of 1 or 2 d of those generated using measured soil temperatures.Key words: Growing degree days, regression, thermal regimes, seed zone temperature, corn emergence

Tobacco Budworm: Effect of Early-Season Terminal Damage on Cotton Lint Yields and Earliness12

Damage to young cotton, Gossypium hirsutum L., by Heliothis virescens (F.) delayed boll opening and decreased first-harvest yields. Larvae placed on plants in the fourth to sixth true-leaf stage caused more delay and fewer cumulative blooms than larvae placed on plants in the sixth to eighth true-leaf stage. The short-season plant type recovered from early-season terminal damage faster than did the long-season plant type. Lint cotton yields decreased as budworm infestation increased. Total yield reductions (Tamcot SP-37) were significant at 60 and 40% infestation levels in 1978 and 1979, respectively. Because earliness is the primary objective of a short-season production system, terminal damage may negate the advantage of these plant types. Longseason plant types may overcome the effects of terminal loss; however, increased hazards such as late-season tobacco budworm damage and rainfall also must be considered. Damaged plants ultimately produced more vegetation than undamaged plants. This increased plant volume could impede the mechanical operation of the stripper harvester and increase the probability of barky lint and reduced quality.

Evaluation of an Integrated Short-Season Management Production System for Cotton1

In a 3-yr field study, a short-season cotton production system was compared with the traditional long-season system. Average cotton lint yields of 3 short-season cultivars were 826 kg/ha as compared with 670 kg/ha for the long-season grower check fields. Four fewer insecticide applications and one less irrigation were required on the short-season test plots as compared with the check long-season fields. Production costs were lower for the short-season system as compared with the Lower Rio Grande Valley (LRGV) of South Texas conventional long-season system. In 1978, the production cost advantage of the short-season production as compared with the conventional was $dollar;0.39/kg of lint produced. A shift to an integrated short-season production system in the LRGV has both economical and environmental advantages over the conventional, long-season system.