June Planting Research Articles

Large-scale assessment of agricultural practices affecting Fusarium root rot and common bean yield

The relationships between a number of agronomic practices, Fusarium root rot (FRR) measurements and yield variables were characterized at different growth stages in 122 commercial bean fields in Zanjan, Iran. Mean FRR incidence, severity and index differed among growth stages and years. A lower FRR index at growth stage R9 and higher yields were detected in Red beans compared to Pinto and White beans. FRR severity affected the number of pods and seeds per plant. Despite the lack of an impact of initial drought on FRR and yield factors, FRR levels were higher following frequent irrigations at 2–3 days intervals than at longer intervals at R6-7. The highest FRR index at R6-7 (51.9%) and incidence at R9 (69.1%) were associated with the densest category of plant populations. Yield components differed significantly between the levels of plant density at R9. FRR levels at V3 were lower for June plantings than for May-second-week plantings. Lower FRR ratings and higher yields were detected at a seeding depth of 0–5 cm in comparison to 10–20 cm. At R9, FRR levels on beans following maize were lower than those following barley, bean, tomato or wheat. At V3, FRR severity was greater in fields that received 50–500 kg/ha of urea compared to non-fertilized fields. Greater mean FRR index at R6-7 and lower yield levels were associated with the greatest weed density compared to weed-free fields. This new information benefits the systematic understanding of interactions between bean yield, FRR and various agronomic variables at large-scale.

Comparison of Early and Conventional Soybean Production Systems for Yield and other Agronomic Traits

The early soybean production system (ESPS) was reported to be beneficial for yield compared to the conventional soybean production system (CSPS) and is widely used in the Southern USA. The objective of this study was to compare yield, yield components, root traits, and shoot traits in ESPS (April planting) and CSPS (June planting) in NC Sandhills using a recombinant inbred line (RIL) population, ‘Hartwig’ by ‘Flyer’ (n=92). The population was grown in Spring Lake, NC in 2008 at a density of 16 seeds m-2. The traits measured were days to germination, days to flowering, plant height, seed weight, seed number, pod number, harvest index, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root number. The survival rate ranged from 83.7 to 90.22% for ESPS; however, it was 21.74% for CSPS. Significant differences were observed for almost all traits measured in ESPS (April) compared to CSPS (June) apart from fresh root weight and lateral root number. An average increase in flowering time of 9 days was observed in CSPS compared to ESPS. On the other hand, several traits showed a significant mean decrease in CSPS compared to ESPS as plant height by 41.96%, seed weight by 74.7%, harvest index by 73.3%, pod number by 65.2%, and seed number by 64.9%. The means for root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, maximum root length, and lateral root numbers are shown in Table 2 for both ESPS and CSPS. The results indicated an average decrease of 40.4% in root fresh weight, of 70.2% in root dry weight, of 68.1% in shoot fresh weight, of 80.1% in shoot dry weight, and of 83.3% in maximum root length in CSPS compared to ESPS. However, lateral root numbers increased by an average of 12.7% in CSPS compared to ESPS. Therefore, CSPS may not be appropriate for soybean at least in NC Sandhills.

沖縄県におけるウコンの植付時期が、出芽、生育および収量に及ぼす影響

The present study was conducted to evaluate the effects of the temperature and planting date (month) on the emergence, growth and yield of turmeric {Curcuma longa L.) plats in Okinawa Prefecture, Southern Japan. Turmeric rhizomes were planted on February 15, March 15, April 15, May 15 and June 15 as treatments for the planting date. Temperature range of 25-35 °C was optimum for the sprouting of turmeric rhizome-buds, and sprouting did not occur below 10 °C or above 40 °C. Seedlings elongated well in the temperature range between 25 and 30 C, but could not survive at above 40 C. The emergence of the turmeric seedlings in the February, March and April plantings started at nearly the same time, and was completed within June. Shoots of turmeric plants differing in the planting month started to wither at the same time in November, and completely withered in January. Shoot dry weight and yield of turmeric plants were significantly higher in the February planting followed by the March and April plantings than in late planting in the glasshouse experiment, whereas in the field experiment the values of these two parameters were significantly higher in the April planting followed by the March and February plantings than in the late planting. The fields of the turmeric plants in the February and March plantings required additional weeding before emergence because winter and spring weeds emerged earlier and grew vigorously. The order of total weed dry weight was as follows: February planting> March planting >April planting >May planting >June planting. The emergence pattern, growth and yield of turmeric plants, and weed growth in the field experiment suggested that turmeric should be planted in April followed by March in Okinawa, Japan.

INTERACTION EFFECT OF DATE OF PLANTING, BULB SIZE AND FERTILIZATION ON YIELD AND QUALITY OF TUBEROSE PLANTS.

A field experiment was carried out on tuberose plant during 2004-2005 and 2005-2006 seasons at a private farm at Demyana near Belqas Dakahlia Governorate. The main objectives of the study were to find out the effect of using NPK compound fertilizer (19:19:19) the common name (High Fertal) fertilizer at three levels (5, 10 and 15g/plant) either alone or combined with compost (150, 200 and 250g/plant). Tuberose bulbs were graded into large, medium and small sizes and planting was during April, May and June of both seasons .Thus, the experiment was a split split plot design with 3 replicates. The obtained results indicated that large size bulbs planted during April and fertilized with the higher levels of NPK +compost gave the maximum number of cut spikes/ pot with more length compared to using medium or small bulbs receiving the same treatment. Large bulbs also produced spikes of more number of florets spike, more spike diameter, and the number of days from planting to opening of the 1st florets was reduced. Also, higher levels of NPK or NPK+ compost increased N, P and K contents in the leaves of large bulbs planted during April, while the lowest contents were for June planting. Thus, it is recommended to use large size bulbs for planting during April and application of NPK at balanced levels along with compost for improvement of soil properties a matter reflexes on flower production.

Corn Response to Delayed Planting in the Central Great Plains

In the central Great Plains, there is growing interest in management options that could improve and stabilize corn (Zea mays L.) production in marginal environments. Limited research exists regarding the practice of delayed planting and its impact in the central Great Plains. Three environments were defined from six location‐years in 2007 and 2008 based on the degree and duration of environmental stress. When planting was delayed from early April to late June grain yields were reduced by 10% in low‐stress environments, increased by 30% with early‐season stress, and decreased by 60% when full‐season stress occurred. In low‐stress and early stress environments, vegetative biomass was greatest for late May to early June planting dates. Leaf area index (LAI) at tassel (VT) also was dependent on planting date, as decreases were not observed in the low‐stress and high‐stress groups until late June planting dates. In the early‐season stress environment, early June planting dates produced the greatest LAI at VT (3.90), and mid‐April planting dates produced the lowest (3.34). These results suggest that scenarios exist where later planting may be a viable alternative for maintaining dryland corn yields in select environments.

Impact of water stress on fresh tuber yield and dry matter content of cassava (Manihot esculenta Crantz) in Côte d'Ivoire.

The production and transformation of cassava (Manihot esculenta Crantz) roots are increasing in Cote d’Ivoire. Characteristics of cassava, at different times of planting and harvesting were studied. For the September plantings, the local cultivar produced less than the improved varieties but maintained a superior dry matter content. In the June plantings, there was no significant difference in fresh root weight. In June planting, the fresh tubers yields showed significant increases up to the harvest after 15 months (43.1 t ha-1) and declined thereafter about 37.01 t ha-1 at 18 months, while dry matter were highest from September plantings with 37.32% at 12 months and regularly reduced until 18 months about 33.18%. The highest dry matter content of cassava tubers is attained when the water stress does not exceed one period in the first 6 months. Dry roots yields were highest (15.27 t ha-1) when roots were harvested in September, but continued to decrease up to 12.59 t ha-1 in December with June planting. These findings suggest that the best time to harvest cassava is September if the aim is to transform cassava into “attieke” for example. Dry roots yield is markedly influenced by environmental conditions, especially water stress immediately before root harvest. Key words: Cassava, seasons, water stress, yields, Cote d'Ivoire.

Effects of Planting Dates and Nitrogen Fertilizer Application on Growth and Yield of Contrasting Genotypes of Maize (<i>Zea Mays</i> L.)I: Leaf Growth and Its Relationship with Grain Yield

Field experiments were conducted at the University of Ilorin Teaching and Research Farm, Bolorunduro, to evaluate the effects of different levels of N application on leaf growth and its relationship with grain yield of contrasting maize genotypes planted at three planting dates. Leaf extension growth at three leaf insertions (nodes 4, 8, and12) was measured from emergence until two consecutive measurements were the same. Thereafter, leaf growth parameters including leaf extension rate, leaf extension duration and final leaf length were calculated by fitting a linear regression of leaf length against time (days after planting DAP). Leaf area index was also calculated at weekly intervals from 21 to 63 DAP. Increasing N application increased leaf extension rate (LER) in both genotypes and at all planting dates, but had no significant effect on leaf extension duration (LED). These results indicate that LER was the most important factor influencing the final leaf area production. Leaf area index was consistently higher with maize planted in May and least with those planted in June. Positive relationships were obtained between grain yield, LER and final leaf area (FLA), while LED showed inverse relationship with grain yield. These results suggested that N application increased grain yield through improved leaf area production resulting from faster LER and shorter LED. The determination of the contribution of leaf growth parameters to grain yield through regression analyses showed that the combined effects of LER, LED, and FLA made significant contribution to grain yield ranging from 33.3%with June planting to 53.4% with July planting. The results further showed that the combined effects of the leaf growth parameters were similar for both the hybrids (R2=47.5%) maize genotypes. Overall, application of 90kg N/ha gave the best leaf area production and hence the highest grain yield thereby indicating the rate to be the optimum for maize production in the study area. JARD Vol. 3 2004: pp. 83-98

Analysis of High Yielding, Early‐Planted Soybean in Indiana

A trend toward early planting of soybean [Glycine max (L.) Merr.] in Indiana results in higher yield, but the limit to which a positive response to early planting occurs has not been evaluated. Our objective was to determine how early planting affects yield components and seed composition of indeterminate soybean planted in late March through early June in Indiana. Three cultivars (Pioneer brand 92M61, Becks brand 321NRR, and Becks brand 367NRR) were sown at six planting dates (late March through early June) in West Lafayette, IN, in 2006 and 2007. Across cultivars, yield in 2006 ranged between 4.24 to 4.43 Mg ha−1 at the planting dates from late March to mid‐May, and decreased to 3.36 and 3.56 Mg ha−1 at later planting dates. In 2007, yield ranged from 4.21 to 4.44 Mg ha−1 for the 10 April, 30 April, and 9 May planting dates. Yield was reduced at the late March and early June plantings and ranged from 3.85 to 3.99 Mg ha−1. Path analysis revealed that pods m−2 had the greatest impact on yield, but seed mass was also an important constituent. Mean oil concentration decreased approximately 12 g kg−1 as planting was delayed in both years. In 2006, average seed protein concentration varied by planting date. In 2007, mean protein concentration increased 14 g kg−1 as planting was delayed. Delaying planting until late May or early June altered seed composition slightly, but significantly reduced yield. Planting in April or early May is an effective management strategy to increase soybean yield in Indiana.

Soybean Response to Plant Population at Early and Late Planting Dates in the Mid‐South

The widespread adoption of glyphosate [N‐(phosphonylmethyl)‐glycine]‐resistant soybean [Glycine max (L.) Merr.] and the increased cost of soybean seed have generated interest in determining the minimum plant population needed for maximum yield. The objective of this study was to determine yield and economic return responses to plant population for normal and late planting dates. Cultivars with relative maturities of 2.8 to 4.9 were planted at five seeding rates (43,000 to 560,000 seeds ha−1) in May and/or June in 38‐cm rows during 2003 to 2005. The effect of plant population on both yield and economic return was explained with a variation of a Mitscherlich equation. Optimum plant population (OPP) and economically optimum plant population (EOPP) were defined as those resulting in 95% of the estimated yield or estimated economic return, respectively, at the maximum plant population. Optimum plant population ranged from 108,000 to 232,000 plants ha−1 for May planting dates and 238,000 to 282,000 plants ha−1 for June planting dates. Economically optimum plant populations were 7 to 33% less than OPPs. Complete canopy cover at R1 produced maximum yield in 8 of 10 comparisons. These results suggest that seeding rates below those that are currently recommended could lower seed costs without reducing yield.

Irrigation and Planting Date Effects on Seed Yield and Agronomic Traits of Early-Maturing Soybean

ABSTRACT Soybean [Glycine max (L.) Merr.] growers in the mid-south United States have increasingly practiced early planting and double-cropping systems. Information on crop management is desired by soybean growers to improve production and profitability. Effects of irrigation and planting date on seed yield and other agronomic traits were investigated in soybean cultivars from eight maturity groups (MG) in 2002 and 2003 at two locations in Arkansas. The planting date (April, May, and June) and irrigation treatments significantly affected seed yield, plant height, and maturity. Significant effects were also observed for number of nodes, number of pods, and number of seeds per plant, whereas number of branches per plant was not affected by planting date and irrigation treatments. Irrigation improved seed yield by an average of 83% (986 kg/ha) in all experiments conducted across two years. Highest seed yield was achieved when soybeans were planted in May, followed by April and then by June planting. The MG V and VI cultivars, conventionally grown in Arkansas, produced higher seed yields than other maturity groups and were the most suitable cultivar selections when considering seed yield alone. Significant interactions were observed among planting date, irrigation, and maturity groups/genotypes. The MG IV was a better candidate for the double-cropping system (June-planting) because of its earlier maturity and high seed yield. For the early soybean production system (April-planting), MG I and II cultivars were potentially good selections because of their short growing periods and acceptable seed yields. The various planting dates and irrigation systems combined with proper cultivar selections provide soybean producers with more options for using the land and water efficiently.

Seeding depth and soil packing affect pure live seed emergence of cuphea

Cuphea viscosissima Jacq. × C. lanceolata f. silenoides W.T. Aiton is a new crop being developed in the north-central USA as an industrial oilseed crop. Adequate plant stand is essential for successful commercial production of cuphea. The objective of this study was to determine the effect of seeding date, depth and soil packing on stand establishment and subsequent crop performance. The study was conducted at Carrington and Prosper, ND, in 2005 and 2006. The experimental design was a randomized complete block with four replicates, with a split–plot arrangement, where the whole plot was a factorial arrangement (2 × 2) of two seeding dates, optimum and late, with or without soil packing after seeding. The subplot treatments were three seeding depths (surface, 13, and 25 mm). The same plot planter was used to adjust seeding depth to 13 and 25 mm. Each experimental unit had six rows 4.6-m long with a between-row spacing of 0.31 m. Traits evaluated were pure live seed emergence (PLSE), plant stand, plant height at harvest and seed yield. The main effect for seeding date did not have an effect on PLSE and resulted in adequate stands from both late May and mid June plantings averaged across environments. The seeding depth by soil packing interaction was significant for PLSE, plant stand and seed yield. Pure live seed emergence, plant stand, and seed yield were greater if the soil was packed compared with non-packed for the surface seeded treatment. The soil packing treatment did not influence PLSE, plant stand, or seed yield at the 13- and 25-mm seeding depths. Plant stands obtained from the non-packed surface and 13-mm seeding depths was adequate for high seed yield, as the plants branched to compensate for the lower plant density. Although surface seeding with packing produced satisfactory plant stands, reliance on timely rainfall is required for this to be successful. For this reason, the recommendation for seeding at the 13-mm depth without soil packing would ensure a better chance for sufficient soil water absorption by the seed to initiate germination. If surface seeding is practiced, a roller-packer to incorporate seeds and firm the seedbed after planting is recommended.

Potential for Using Sunn Hemp as a Source of Biomass and Nitrogen for the Piedmont and Coastal Plain Regions of the Southeastern USA

The tropical legume sunn hemp (Crotalaria juncea L.) could be a valuable green manure/cover crop for vegetable producers in the southeastern USA because of its rapid growth and large N2 fixing ability. Planting and termination date effects on biomass and N accumulation are relatively unknown for the region, but would help producers manage sunn hemp between summer and winter cash crops. We determined sunn hemp biomass and N content at 30, 60, 90, and 120 days after planting (DAP) for four planting dates (mid‐April to mid‐July) at a Piedmont and a Coastal Plain location in Georgia. Maximum biomass at a given DAP was produced from May and June plantings in the Piedmont and from April and May plantings in the Coastal Plains. Maximum biomass and N ranged from 8.9 to 13.0 Mg ha−1 and 135 to 285 kg ha−1, respectively. An equation for estimating sunn hemp biomass as a linear function of cumulative degree days (CDD) and cumulative solar radiation (CSR) was verified with independent data from Alabama, Florida, and Virginia. A similar equation for estimating N content as a quadratic function of CSR was not as accurate but still might be useful. Sunn hemp can fit well into short‐rotation sustainable vegetable production systems in the Southeast, and these equations can be used by producers to make reliable estimates of sunn hemp biomass production.

Carbon, nitrogen and phosphorus leaching after site preparation at a boreal forest clear-cut area

Clear-cutting followed by mechanical site preparation is the major disturbance influencing nutrient and water fluxes in Fennoscandian boreal forests. The effects of soil harrowing on the fluxes of dissolved organic carbon (DOC), dissolved nitrogen compounds (organic N, NH 4 + and NO 3 −) and water soluble phosphorus (PO 4 3−) through a podzolic soil were studied in a clear-cut in eastern Finland for 5 years. The old, mixed coniferous stand was clear-cut and stem only harvested in 1996 followed by soil harrowing in 1998 and planting in June 1999. Zero-tension lysimeters were used to collect soil water from below different soil horizons in the three types of microsites that resulted from site preparation treatment: low ridges (25% of clear-cut area), shallow furrows (30%) and the undisturbed soil (45%). After soil harrowing, the leaching of DOC, N and P from below the B-horizon increased compared to pre-treatment levels. However, the increases were short-lasting; 1–2 years for inorganic N and P, and 5 years for DOC and organic N. The highest concentrations were associated with the ridges and lowest with the furrows, reflecting the differences in amount of organic matter present in each microsite type and, for N, to enhanced mineralization and nitrification. Leaching from below the B-horizon over the 5 years following soil harrowing for the whole clear-cut area was 36.5 kg ha −1 for DOC, 0.88 kg ha −1 for NH 4-N, 0.46 kg ha −1 for NO 3-N, 1.24 kg ha −1 for organic N and 0.09 kg ha −1 for PO 4-P. Site preparation increased temporarily the risk for nutrient leaching into watercourses and groundwater from the clear-cut area but soil fertility was not affected since the leached amounts remained small. The main reasons for the observed low leaching values were the rapid recovery of ground vegetation and low N deposition loads.

EFFECTIVE FLOWERING TIME VARIATIONS IN UPLAND COTTON (GOSSYPIUM HIRSUTUM) AT DIFFERENT PLANTING DATES AND STAND DENSITIES IN BENIN

Effective flowering time in Gossypium hirsutum cotton plants was studied with the aim of enhancing decision making on the best varieties to plant according to the planting date under rainfed cropping conditions. Trials were conducted at two sites in a cotton-growing area of Benin in 2002 and 2003. A split-split plot design with three replicates was used to compare 10 cotton varieties, with different growth cycle lengths and morphology, at three stand densities (42 000, 125 000, 167 000 plants ha−1) and two planting dates (standard planting in June and late planting). The flowering period was characterized by the mean first flower opening date (FF), which is an indicator of flowering earliness, and by the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1). Effective flowering time (EFT) was calculated as the difference between LFP1 and FF. EFTs differed markedly in the 10 cotton varieties tested and this parameter could not be predicted on the basis of flowering earliness. Late planting and high planting rates delayed first-flower opening, accelerated last-boll development and reduced the effective flowering time. This latter factor should be taken into account in cotton breeding programmes so that varieties adapted to local rainfall constraints can be recommended to growers while also enhancing crop management sequences.

Evaluation of Rhizoma Peanut Genotypes for Adaptation in Texas

Rhizoma peanut (Arachis glabrata Benth.) is a warm‐season perennial forage legume adapted to the extreme southern USA. The objectives of this study were to compare the establishment rate and overall adaptation of ‘Florigraze’, ‘Arbrook’, PI 262819, and PI 262821 rhizoma peanut in south and north‐central Texas. Two separate field experiments were initiated to evaluate establishment rate and adaptation of rhizoma peanut. In the first experiment, the rate of establishment was documented by measuring shoot appearance in parallel zones equidistant from the original planting. In the second experiment, shoot spread (distance to farthest shoots) was measured 26 mo after planting and dry matter (DM) yield was estimated 1, 2, and 4 yr after planting in south Texas. In 1991, a dry year, PI 262819 had a greater number of total shoots in June and shoots in the zone farthest from the original planting in June and September compared with other genotypes. In 1992, Florigraze, PI 262819, and PI 262821 did not differ from each other in total shoot counts or counts within each zone; however, all were superior to Arbrook. In the second experiment, spread was greatest among genotypes for PI 262821 in south Texas, and for PI 262819 in north‐central Texas. Total DM yield in south Texas was greatest for Arbrook the first season after planting; however, there were no differences in yield between genotypes in subsequent years. Rate of establishment and adaptation of PI 262819 and PI 262821 were equal to or better than Florigraze and Arbrook in both south and north‐central Texas.

Obvious and Cryptic Vole Suppression of a Prairie Legume in Experimental Restorations

Ecological conditions may amplify or diminish effects of herbivory. We use replicated prairie plantings established in 1997 to test for the effects of two components of ecological conditions, planting density (high or low density at a 10-fold difference) and planting season (spring or fall), on meadow vole (Microtus pennsylvannicus) herbivory of the prairie perennial Desmanthus illinoensis Michx. (Fabaceae). Over 3 yr, Desmanthus counts declined in plots planted at high density and in December compared with those planted at low density and in June. In 2000, obvious suppression of Desmanthus by voles was reduction of numbers: overall, Desmanthus was 58% less common in plots with vole access than in those without and was virtually eliminated where voles had access in December plantings. In June plantings, direct but cryptic suppression by voles reduced plant biomass (� 51%), fecundity (� 44%), and seed mass (� 50%). In June plantings, Desmanthus adults produced nearly 3000 fewer seeds, each with half the mass, where voles had access compared with where they did not. Desmanthus abundance was much reduced in December plantings, where remaining individuals were smaller and had lower reproductive output than in June plantings, with vole herbivory accentuating seasonal effects. Our results offer insights into the reasons why populations of this legume are sparse in much of central North America and why restoration plantings of this plant sometimes fail.

Summer Squash Planting Systems Following a Rye Cover Crop

Commercial organic vegetable production requires using soil improvement practices and effective weed control measures. Rye (Secale cereale) cover crops are known to suppress annual weeds. Research was begun in 2004 to measure crop yield, annual weed infestation, and weed control requirements for vegetable planting systems that begin with a rye cover crop. Poultry litter was used to supply nutrients and was applied based on a soil test and commercial vegetable recommendations. Rye `Elbon' was seeded 21 Oct. 2004 on beds with 1.8-m centers. Zucchini squash (Cucurbita pepo) `Revenue' was planted the following year using three crop establishment dates, such that transplanting occurred on 6 May, 3 June, and 29 June. Planting system treatments included: conventional tillage (CT), CT and plastic mulch (P), CT with stale seedbed, mow, mow and burn-down, mow and shallow till (ST), ST and burn-down. Following field preparation, squash was transplanted in a single row at the bed center with 0.77-m plant spacing. Drip irrigation was used in all plantings. Emerging weeds were removed by hoeing. Squash was harvested from each planting over approximately 3 weeks and total marketable fruit counts were determined. Marketable yields with P were approximately double those of the CT and ST treatments in the 6 May transplanting. Yields were comparable for CT and ST in the 3 June transplanting, but were significantly lower for the P treatment. There were no significant differences among the treatments that received tillage in the 29 June planting. However, the non-tilled treatments had significantly lower yields compared to tilled treatments.

Timing of planting is crucial for cotton yield

A field study has been conducted to evaluate the importance of planting dates on earliness and second crop seed cotton yield in two cotton cultivars (Gossypium hirsutum L.). The experiment was designed as a split-plot with three replications in which planting dates were the main plots and cotton cultivars were subplots. Five planting dates were established at about 15-day intervals from mid-April to mid-June (15 April, 1 May, 15 May, 1 June, and 15 June). Data collected in both years indicated that planting on 15 April increased the seed cotton yield by 15%. 1 June planting resulted in lower yield (28%), micronaire (15%) and strength (10%) compared to 1 May. Short fibre content was 35% higher for the 15 June planting than for 1 May planting. Cultivar responses differed with planting date. The existence of cultivar×planting date interaction on yield highlights the importance of selecting the right cultivar for the specified planting date. An early planting production system for cotton has the potential to increase yield and quality. Planting cotton as a second crop after cereals could also be feasible for the regions which have an expanding textile industry, although yield and quality are not as high as in crops grown at optimum planting date.

Agronomic practises for weed control in turmeric (Curcuma longa L.)

Weeds are the main problem with turmeric (Curcuma longa L.) cultivation where herbicides are not allowed. This is because herbicides cause water contamination, air pollution, soil microorganism hazards, health hazards, and food risks. Considering turmeric's medicinal value and the environmental problems caused by herbicides, various agronomic practises have been evaluated for non‐chemical weed control in turmeric. One additional weeding is required before turmeric emergence and weed infestation is much higher when turmeric is planted in February and March, as compared to April, May or June planting. A similarly higher yield of turmeric is achieved when it is planted in February, March, and April, compared to late plantings. Weed emergence and interference are not affected by planting depth, seed size, planting pattern, planting space, ridge spacing, and the row number of turmeric until 60 days after planting. This is because turmeric cannot develop a canopy structure until then. Thereafter, weed infestation reduces similarly and significantly when turmeric is planted at depths of 8, 12, and 16 cm, compared to shallower depths. The yield of turmeric at these depths is statistically the same, but the yield for the 16 cm depth is difficult to harvest and it tends to decrease. Turmeric grown from seed rhizomes (daughter rhizomes) weighing 30–40 g reduces weed infestation significantly and obtains a significantly higher yield compared to smaller seeds. The mother rhizome also can suppress weed infestation and increase the yield markedly. Around 9% weed control and 11% higher yield are achieved by planting turmeric in a triangular pattern compared to a quadrate pattern. The lowest weed infestation is found in turmeric grown in a 20 or 30 cm triangular pattern and the highest yield is obtained with the 30 cm triangular pattern. Turmeric gown on two‐row ridges spaced 75 cm apart shows excellent weed control efficiency and obtains the highest yield. This review concludes that turmeric seed rhizomes of 30–40 g and/or the mother rhizome could be planted in a 30 cm triangular pattern at the depth of 8–12 cm on two‐row ridges spaced 75–100 cm apart during March to April in order to reduce weed interference and obtain a higher yield. Mulching also suppresses weed growth and improves the yield. The above agronomic practises could not control weeds completely; biological weed management practises could be integrated in turmeric fields using rabbits, goats, sheep, ducks, cover crops or intercrops.

Temporal profiles of pod production and pod set in soybean

The distribution of flower and pod production during flowering may be an important determinant of pod and seed number in grain crops. We characterized the dynamics of small pod production and survival to maturity on indeterminate and determinate soybean [ Glycine max (L.) Merrill)] cultivars growing in the field or greenhouse. Two soybean cultivars (maturity group IV, indeterminate and determinate) were grown in the field near Lexington, KY (38°N latitude) in 2001 and 2002 in 0.76 cm rows using late May and late June (2002 only) planting dates, and normal (24 plants m −2) and low (9 plants m −2, 2002 only) plant populations. Cultivar Elgin 87 (indeterminate, maturity group II) was grown in a greenhouse in 3.0 L pots with one plant per pot. All unmarked pods that were ≥10 mm long were marked with acrylic paint at the base of the pod at 3-day intervals. Paint color was changed at each marking to provide a temporal profile of pod production and pod survival. The pod production (marked pods) period was longer in the indeterminate cultivar (nearly 50 days after R1) than the determinate cultivar (≤40 days after R1). Delayed planting shortened the pod-production period, but a two- to three-fold difference in pods per plant, created by changing plant population, did not affect it. The temporal distribution of small pods that survived to maturity (full sized pods with at least one normal seed) closely followed the distribution of pod production in all experiments. Some surviving pods initiated growth after the beginning of seed filling (i.e., between growth stage R5 and R6), but most of the pods were initiated in a much shorter interval (up to 84% were initiated in <40% of the period) before R5. Abortion of pods >10 mm long was relatively low (20–30%), so production of a pod ≥10 mm long seems to be a key event in the pod set process. The average length of the pod set period at individual nodes on the main stem was larger for the determinate cultivar (14 days) than for the indeterminate (9 days), so the longer total period in the indeterminate cultivar resulted from the delay in initating pod production at the upper nodes on the main stem. Temporal profiles of pod production and pod set seem to be more sensitive to changes in flower and main stem node production than to changes in photosynthesis per plant (created by varying plant population). These results provide some of the information needed to integrate time into models predicting pod and seed number.