Late Sowing Research Articles

Mepiquat chloride effects on potassium acquisition and functional leaf physiology as well as lint yield in highly dense late-sown cotton

Incredible accomplishments have been achieved in agricultural production in China, but many demanding challenges for ensuring sustainable cotton production remain. An efficient cropping model characterized with late sowing, higher density and low fertilizer application is a promising alternative to cope with the present high cost cotton production. However, it is not confirm that mepiquat chloride (MC) application is still required in this new planting model. We hypothesized that MC application might reduce lint yield and thus not be necessary in this new system. A 2-year (2015–2016) field experiment was performed to test this hypothesis in which cotton was planted in mid-May at 10 plants m−2 and with single fertilizer application (225 kg N ha-1). MC was sprayed thrice with 5 leaf intervals initiated from the 6th leaf stage in 5 different dosages i.e. 0 (control), 30, 60, 90, and 120 g ha-1. Morphological attributes viz. plant height, main stem diameter, number of fruiting branches, main stem nodes, main stem green leaves and main stem internode length were evidently reduced by 9–40%, 2–13%, 2–11%, 4–27%, 6–24% and 3–19%, respectively. Cotton potassium accumulation was not significantly influenced; specifically the uptake in reproductive organs from MC0 to MC120 of 45 to 44 kg K ha-1 in MC treated plants averaged across two years. Photosynthesis was reduced by 1–26% due to diminished Rubisco activity by 3–37% in MC treated plants and lint yield decreased by 5–27% as MC dosage increased. Furthermore, alpha amylase, beta amylase and total amylase activities were decreased by 2–16%, 3–19% and 1–17% but sucrose transformation rate was increased in the 4th functional leaf from the apex, respectively. Our data suggest that increased accumulation of sucrose and starch in the leaf with reduced photosynthesis, Rubisco and amylase activity could explain the yield loss. Conclusively, MC application is not needed for this new cotton planting model in Yangtze River Valley of China.

Prohexadione-Calcium and Nitrogen Topdressing Fertilisation on Productive Performance of Maize with Late Sowing

Prohexadione-Calcium and Nitrogen Topdressing Fertilisation on Productive Performance of Maize with Late Sowing

Foliar Application of Organic Compounds Stimulate Cotton (Gossypium barbadense L.) to Survive Late Sown Condition

Abstract Application of organic compounds in cotton balances its vegetative and reproductive growth, as well as to improve the seed cotton yield and lint quality properties. Field experiments were conducted with some organic compounds to determine their effects on cotton yield and quality properties of cotton under two sowing times.The experiment was conducted at Sakha Agricultural Research Station, Cotton Research Institute, Egypt in 2015 and 2016. In these studies, two sowing times viz. optimum and delay sowing and two levels (200 and 400 ppm) of organic compounds viz. ascorbic, ascobine and salicylic acids were used. The results indicated that the optimum sowing date gave the largest area of single leaf at 90 and 120 DAS, as well as it induced an increase in dry weight (g) of plant organs at 120 DAS, while, the late sowing significantly reduced the leaves dry weight both at 90 and 120 DAS. Both seed cotton yield and lint cotton yield (kentar feddan-1) were significantly increased in optimum sowing condition and sharply declined as delayed sowing date. The number of opened bolls plant-1 were also significantly reduced in late sowing. Lint percentage, seed index and seed cotton weight boll-1 were also significantly affected by sowing dates. Leaf pigment (total chlorophyll) was significantly affected by sowing date recorded at 90 and 120 DAS, while lower values of total chlorophyll was recorded in late sown plants. Also, sowing dates had no significant effect on both oil and protein seed content. This study has shown that timely sowing of cotton seed and foliar application of ascorbic acid, ascobine or salicylic acid with concentration of 200 or 400 ppm at flower initiation stage and peak of flowering stage had significant positive effects on seed cotton yield and lint quality properties. According to these results it can be suggested that usage of organic compounds to improve the yield and quality properties, especially in late sowing for ‘Giza 94' cotton cultivar at Kafr- Elsheikh district, Egypt.

Nitrogen economy of early and late-sown maize crops

Late sowing dates of maize are widely adopted in the Pampas region of Argentina, stabilising grain yields due to a more favourable water balance around flowering. However, late-sown crops are exposed to high soil N availabilities (Nav), high temperatures during the pre-flowering period and declining photo-thermal conditions during grain filling, which may affect nitrogen use efficiency (NUE, kg of grain per kg of Nav). These effects could be exerted through nitrogen uptake efficiency (NupE, kg of N uptake per kg of Nav) and/or nitrogen utilisation efficiency (NutE, kg of grain per kg of N uptake). Environmental conditions could affect i) pre (Nuptpre) and/or post-flowering N uptake (Nuptpost) and, consequently, NupE and ii) the determinants of NutE, such as N harvest index (NHI) and N source per grain. Early- and late-sown maize were cropped in order to analyse i) grain yield, Nav and NUE and ii) relationships among NUE and related-N efficiencies. The experiments were carried out in Paraná (31°48′ S 60°32′ W), Argentina, during 2014–2015 and 2015–2016. Treatments were combinations of two sowing dates (early and late), three N rates (0, 90, and 270 kg N ha−1) and two genotypes (DK 70-10 VT3P and DK 73-10 VT3P). NUE decreased in late-sown crops (ca. 32 to 26 kg grain kg Nav−1), mediated by lower grain yields (ca. 8564 kg ha−1 and 7832 kg ha−1 in early- and late-sown crops, respectively) and higher Nav (ca. 267–312 kg Nav ha−1). DK 73-10 VT3P exhibited the highest NUE (ca. 31 kg grain kg Nav−1) and NutE (ca. 63 kg grain kg Nupt−1). N rate affected more strongly Nav than grain yield; and there was a greater association between NUE and NupE (P < 0.0001, R2 = 0.72) relative to NutE (P < 0.01, R2 = 0.65). In both sowing dates, Nuptpre had a positive impact on NupE, which strongly declined with N rate especially in late-sown crops. The lower NutE of late-sown crops (66 vs. 52 kg grain kg Nupt−1 in early and late sowing dates, respectively) was related to the highest post-flowering N source per grain (2.5 vs. 3.5 mg N grain−1). Thus, our study highlights the components of N economy of late-sown crops with the highest impact on NUE, i.e., Nuptpre and NutE. Therefore, nutritional management of late-sown maize crops should be focused on these NUE components. High plant densities could be useful to increase Nuptpre. Finally, the choice of a genotype with high NutE appears as a valid strategy to mitigate NUE reductions, promoted by the high Nav typical of late sowing dates.

Response of chickpea genotypes to drought stress under normal and late sown conditions

Chickpea (Cicer arietinum L.) is one of the important legumes widely grown for dietary proteins in semi-arid Mediterranean climatic conditions. Thirty-four selected chickpea genotypes were tested under two (winter and late sowing) conditions to assess the genetic diversity for drought tolerance capacity. Factorial experiment in randomized complete block design with three replications was conducted during 2015 and 2016 at the Eastern Mediterranean Agriculture Research Institute Adana, Turkey. Significant differences and reduction was observed amongst the genotypes under stress condition compared to normal one. All traits except seed yield and hundred seed weight in 2015 were higher than those in 2016. Besides, all investigated traits significantly decreased in stress condition experiment compared to non-stress one in both years. It was observed that seven genotypes viz., ICC 1205, ILC 8617, ILC 4567, FLIP 03-21 C, FLIP 03-42 C, FLIP 01-24 C and ENA 8-2 genotypes provide early expressed early vegetative growth stages. Besides, Aksu, Arda, Çakýr, Dikbaþ, EN 808, ENA 8-2, FLIP 03-108 C, ICC 1205 and Seçkin had high seed yield under drought conditions during two years. Therefore, these genotypes can be used as donors of drought tolerance in future breeding program of chickpea.

Biplot Yield Analysis of Heat-Tolerant Spring Wheat Genotypes (Triticum Aestivum L.) in Multiple Growing Environments

Abstract It is important to identify and develop stable wheat varieties that can grow under heat stress. This important issue was addressed in Bangladesh using six wheat genotypes, including three existing elite cultivars (‘BARI Gom 26’, ‘BARI Gom 27’, ‘BARI Gom 28’) and three advanced lines (‘BAW 1130’, ‘BAW 1138’, ‘BAW 1140’). Six sowing dates, namely early sowing (ES) (10 November), optimum sowing (OS) (20 November), slightly late sowing (SLS) (30 November), late sowing (LS) (10 December), very late sowing (VLS) (20 December) and extremely late sowing (ELS) (30 December) were assessed over two years in four locations, representative of the diversity in Bangladesh’s agro-ecological zones. In a split plot design, sowing dates were allocated as main plots and genotypes as subplots. A GGE biplot analysis was applied to identify heat tolerance and to select and recommend genotypes for cultivation in heat-prone zones. All tested genotypes gave greatest grain yield (GY) after OS, followed by SLS, ES and LS, while VLS and ELS gave smallest GY. When GY and the correlations between GY and stress tolerance indices were considered, ‘BAW 1140’, ‘BARI Gom 28’ and ‘BARI Gom26’ performed best under heat stress, regardless of location or sowing date. In contrast, ‘BARI Gom 27’ and ‘BAW 1130’ were susceptible to heat stress in all locations in both years. Ranking of genotypes and environments using GGE biplot analysis for yield stability showed ‘BAW1140’ to be most stable, followed by ‘BARI Gom 28’ and ‘BARI Gom 26’. Wheat sown on November 20 resulted in highest GY but that sown on December 30 resulted in lowest GY in both years. In conclusion, ‘BAW 1140’, ‘BARI Gom 28’ and ‘BARI Gom 26’ are the recommended wheat genotypes for use under prevailing conditions in Bangladesh.

Effect of level of irrigation and nitrogen rate on yield performance of late sown wheat

The experiment was at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh–2202 during late Rabi season (December-March) of 2015. It was two factorial experiment (1) irrigation level and (2) nitrogen rate. Irrigation significantly influenced on yield and yield contributing characters except harvest index. The highest plant height (79.69cm), maximum number of total tillers plant-1 (4.725), number of grains spike-1 (40.61), spike length (11.80cm), 1000 grain weight (28.67g), grain yield (3.227 t ha-1), harvest index (41.26%) were obtained by mulching treatment. Nitrogen rate significantly influenced the yield and yield contributing characters. The highest plant height (80.37cm), maximum number of total tillers plant-1 (5.124), number of grains spike-1 (40.85), spike length (10.37cm), 1000 grain weight (31.86g), grain yield (3.792 t ha-1), harvest index (41.69%) were obtained by the application of 180 kg N ha-1. The combined effect of Irrigation and nitrogen significantly interacted on yield and yield contributing characters. The highest plant height (83.44cm), number of total tillers plant-1 (5.66), number of grains spike-1 (41.60), 1000 grain weight (36.66g), grain yield (4.32 t ha-1) and harvest index (47.36%) were obtained by application of 180 kg N ha-1 with mulching. The present study revealed that high dose of nitrogen 180 kg ha-1 and mulching practice can compensate low production of wheat even at late sowing.&#x0D; Progressive Agriculture 29 (3): 213-220, 2018

Breeding wheat varieties of different development types adapted to different growing conditions

Aim. When forming optimal sowing structure, considering certain conditions of soil and climate zones, a particular region and farm, it is necessary to have a complex of varieties with different levels of plasticity, stability and the length of a growing season, the duration of a vernalization stage and photoperiodic sensitivity. Methods. The research was conducted according to the methods of field experiments. The winter wheat varieties included and the wheat varieties of an alternative type of different genetic and ecological origin were used in the research. Results. The purposeful inclusion of the wheat varieties Znakhidka odeska, Khersonska unbearded, the variety of an alternative type Nevesinjka 471, NS 446 and others into hybridization by a diallel scheme allowed realizing the complexes of such features as fast maturation, 1000 grain weight, adaptive properties in the offspring resulting in high productivity. The promising lines selected in the breeding process became the basis for developing new winter wheat varieties Askaniiska, Askaniiska Berehynia, Perlyna and the varieties of an alternative type Solomiia, Klarysa. Conclusions. The conducted research resulted in developing promising soft winter wheat varieties and the varieties of an alternative type, which ensure high and steady grain yields, especially under late sowing dates. Keywords: winter wheat, varieties of an alternative type, combining ability of genotypes.

Effects of late sowing on soybean yields and yield components in southwestern Japan

ABSTRACTSoybean production in southwestern Japan tends to be unstable owing to wet soils during the rainy season. Although late sowing after the rainy season can avoid excess water, information on its yield potential is limited. The objective of this study was to reveal the effect of late sowing on yields and yield components of new soybean cultivars developed for warm regions. The experiment was conducted in 2016 and 2017 in Fukuyama, Hiroshima, Japan. Upland fields converted from paddy fields with a subirrigation system were planted in June (normal) or July (late sparse or late dense). Lodging was prevented with a net. The effects of late sowing and dense treatment were analyzed in relation to solar radiation use. In 2016, differences in yield among cultivars and among environments were not significant. In 2017, yield was significantly reduced following late sparse sowing. The total aboveground dry matter at maturity was correlated with total solar radiation intercepted (r = 0.76) but not with radiation use efficiency (r = 0.47). Late sowing increased harvest index (HI) significantly from 0.464 to 0.571 in 2016 and from 0.524 to 0.585 in 2017, but density had no significant effect. The changes in HI were correlated with stem dry weight (r = −0.80 in 2016 and r = −0.79 in 2017) rather than seed yield (r = 0.08, n.s. in 2016 and r = 0.19, n.s. in 2017). Thus, under irrigation, late dense sowing might stabilize yield in southwestern Japan because of higher HI.Abbreviations: DM: dry matter; FOEAS: farm-oriented enhancing aquatic system; HI: harvest index; RUE: radiation use efficiency

Early Sowing of Grain Legume Crops after Rice Harvest Increases Grain Yield

Most paddy fields in Timor Leste are abandoned after harvesting the rice crop due to limited supplemental irrigation. Other field studies have identified some drought-adaptive grain legumes including kidney bean (previously grown in cold, highland areas only), Ceora grass pea (Lathyrus sativus L., a newly introduced species), mung bean, and soybean for growing after rice harvest. The impact of sowing date on growth and yield after rice harvest is not well understood. The current study aimed to identify the appropriate sowing time of grain legumes after rice harvest. Seeds of kidney bean and grass pea were sown in plots arranged in a randomized block design with three factors (species, drought treatment, and sowing date) and three replications. There were three sowing dates at monthly intervals: 28 May (D1), 28 June (D2) and 28 July 2017 (D3). The terminal drought treatment was applied at first flower of grass pea or pod set of kidney bean for each sowing date. Overall, kidney bean produced more seed yield (32% higher) than grass pea. Yields of both species decreased at the later sowing dates (P<0.001). Grass pea produced 78% more filled pods than kidney bean, but 34% fewer seeds per pod and 58% smaller seeds than kidney bean. Seed weight in both species decreased at later sowing dates as did seeds per pod in kidney bean, but grass pea maintained seed numbers per pod at all sowing dates. Dry matter production between species was comparable, which declined at later sowing dates (P<0.001). In conclusion, early sowing of grain legumes produces more seeds and biomass after rice harvest than late sowing.

Potassium to nitrogen ratio favors photosynthesis in late-planted cotton at high planting density

Late sowing of short growing season cotton, planted in high density with one time fertilization is a potential economic alternative for the conventional cotton growing practice in the Yangtze River Valley, China. The appropriate proportion of nutrients is indispensable for an economic crop production. Therefore, the present study was designed to explore the best relative ratios of potassium (K) to nitrogen (N), under a new short-season and high density planting model, based on the photosynthetic performance of cotton plants in relation with the yield. A two-year (2016–17) field experiment was conducted with three K relative ratios to N [0.8 (K08: 168 kg ha−1 K2O), 1.0 (K10: 210 kg ha−1 K2O) and 1.2 (K12: 252 kg ha−1 K2O)]. The results indicated that K10 increased seed cotton and lint yield by 10–20% and 10–24%, respectively, over K08 and no difference was existed between K10 and K12. Similarly, K10 and K12 increased SPAD value by 3–10% and 11–18%, photosynthetic rate by 7–57% and 0.7–89%, and chlorophyll fluorescence parameters by 1–8% and 1–29%, respectively, as compared to K08. And the highest photosynthetic attributes were achieved for the 4th main stem leaf from the top at peak bloom (PB) stage. These results suggested that the K10 is the most suitable ratio as for cotton yield and economic concerns under the newly proposed planting model in the Yangtze River Valley, China.

Chlorophyll content measurement of drought tolerant wheat genotypes sown at normal and late conditions as an indicator of spot blotch resistance

A field experiment was conducted at Agronomy block of the Institute of Agriculture and Animal Science (IAAS), Rampur to evaluate chlorophyll content of 20 drought tolerant wheat genotypes as a parameter of stay green character and spot blotch response. The experiment was laid out in a split plot design with three replications, considering 25 November as normal sowing and 15 December as late sowing dates. Of the tested genotypes, Aditya had highest SPAD value (46.67) with least AUDPC (146) on flag leaf on 25 November sowing and higher SPAD value (43.57) with lower AUDPC (161) on 15 December sowing. Similarly, CSISA DRYT 5204 and CSISA DRYT 5205 had moderate SPAD values with AUDPC value at par with Aditya. Aditya with low AUDPC possessed longer stay green days (118.3) on 25 November sowing and shorter green days (107.5) on 15 December sowing. The susceptible check variety RR-21 possessed shorter stay green days (113.6) with SPAD value (35.7) on 25 November sowing and 100.4 days of stay green with SPAD value (31.23) on 15 December sowing. Aditya also had highest grain yields and thousand kernel weights on both the 25 November and 15 December sowing. The results showed Aditya, CSISA DRYT 5204 and CSISA DYRT 5205 were having longer period of stay green with higher SPAD and low AUDPC values and thus these three genotypes can be recommended for late sown conditions. Journal of the Institute of Agriculture and Animal Science. Vol. 33-34, 2015, Page: 65-72

IInfluence of sowing times and plant populations on the agronomic performance of maize hybrids

The sowing time, along with increased plant density and the choice of the hybrid, are among the main factors to obtain higher grain yields in second-season maize. The objective was to evaluate the agronomic performance of maize hybrids grown in different plant populations and sowing times. The experimental design was in randomized blocks with subdivided plots and four replicates. The main plots consisted of four sowing times (Jan/20/2014, Feb/07/2014, Feb/28/2014, and Mar/14/2014), the subplots consisted of the hybrids (BRS 1010 and DKB 390 VT PRO2), and the sub-subplots consisted of the plant populations (45,000; 55,000; 65,000 and 75,000 plants ha -1 ). Regardless of plant population, the performance of hybrids BRS 1010 and DKB 390 VT PRO2 are similar regarding grain yield, plant height, and number of rows per ear. The development of maize was better in the sow­ings performed between Jan/20 and Feb/07, and very late sowings negatively affect yield. Among the hybrids studied, in a population ranging from 45,000 to 75,000 plants ha -1 there is a reduction in ear diameter and hundred-grain weight, although without affecting yield.

Caractéristiques de l’évolution spatio-temporelle de Pectinophora gossypiella Saunders (Lepidoptera : Gelechiidae) dans les zones de production cotonnière de Côte d’Ivoire : Implications pour une stratégie de gestion optimale de la résistance aux pyréthrinoïdes

In order to update knowledge on the spatio-temporal evolution of Pectinophora gossypiella, the geographical areas and the seasons of predilection of adult and larval populations have been studied in the last six years from 2012 to 2017. The study showed that adult populations are more abundant in the cotton production area of the South compared to the North. They have a very low activity during the intercropping season while the most important outbreaks occurred in October-December. The monitoring of larval populations carried out on farm scale showed that infestations started on cotton early August and increased until November, which leads to a strong relationship between the evolution of adult populations, larval infestations and cotton plant phenology. Late sowings D5 and D6 exhibited higher levels of infestation (0.50 to 0.80 larvae/100 bolls) as compared to early sowing (0.21-0.31 larvae/100 bolls). Annual variations of pest infestation levels increased from years to years, fluctuating from 0.14 to 0.95 larvae/100 bolls over the study period. Mapping of the geographic distribution of infestation showed more severe pest pressure in the southern cotton areas, mostly in surrounding areas of Bouaké, Bouaflé, Séguéla and Boron (18,90; 5,33; 1,52; 1,06 larvae/100 bolls respectively). With regard to the emerging status of P. gossypiella over recent years, the current pyrethroid resistance management strategy deserves to be improved on the basis of the pest geographic and seasonal profiles.

Mitigating heat and chilling stress by adjusting the sowing date of maize in the North China Plain

AbstractThe North China Plain (NCP) is one of the major areas of cereal production, and in recent years its maize (Zea mays L.) production has been influenced by both heat and chilling stresses. Adjusting the sowing date is an effective measure for mitigating these stresses. However, the underlying mechanisms remain poorly understood. We performed a 5‐year field experiment to determine how the sowing date mitigated heat and chilling stresses at Wuqiao Experimental Station in the NCP with three treatments: early sowing (ES), middle sowing (MS), and late sowing (LS). In all 5 years, higher grain yields were observed in the MS (averaged 11.7 Mg/ha) and LS (averaged 11.4Mg/ha) treatments compared with the ES (averaged 10.9Mg/ha) treatment. The lower yield in ES treatment mainly resulted from high temperature 5 days pre‐silking and 5 days post‐silking (&gt;31.8°C). In 2015 and 2016, the lower grain yield in LS (11.4Mg/ha in 2015 and 11.2Mg/ha in 2016) treatment compared with MS (12.1Mg/ha in 2015 and 11.9Mg/ha in 2016) was mainly because the minimum temperature was &lt;13.0°C 5 days before maturity or &lt;13.6°C 10 days before maturity. Long‐term weather data further verified middle sowing would be appropriate in a changing climate. Therefore, we can conclude that sowing date manipulation constitutes a useful method for mitigating heat and chilling stresses for maize production.

Response of tomato (Lycopersicon esculentum Mill.) growth to different phosphorous levels and sowing dates

A field trail was carried out at the University of Agriculture Peshawar during spring, 2013 in order to evaluate the effect of different levels of phosphorus fertilizer and various planting times on the growth and development of tomato. The main objective of the research work was to investigate the best sowing time for tomato in combination with suitable dose of P fertilizer in order to get maximum yield of tomato in the climatic conditions of Peshawar. RCB Design with split plot arrangements was used in the trail. The main factor (phosphorous levels of 0, 90, 110, 130) was allotted to main plots while sowing dates in sub plots. A total twelve treatment were replicated thrice. Maximum days to flowering (39.583 days) and fruiting (46.167 days) obtained in the late sowing. Minimum days to flowering (39), minimum days to fruiting (38.778 days) were taken by the early sowing. Maximum number of branches (27.778), maximum fruit length (6.0222), maximum fruit with (6.1667), maximum fruit yield (24.653 tons ha−1) was produced when the plot fertilize with 130 kg P ha−1. Maximum number of fruit plant−1 (29.778) were produced with application of 130 kg P ha−1, minimum number of fruits (23.667 cm), fruit width (3.778 cm), fruit length (4.3667 cm), plant height (56.300 cm) were obtained from the controlled treatment. Among the various treatment studied in experiment, it is concluded that early planting of the tomato in the summer season i.e. in the start of March and the use of higher dose of P (130 kg P ha−1) is very beneficial for the excellent growth, development and yield of tomato crop.

Yield and Physical and Physiological Quality of Salvia hispanica L. Seeds Grown at Different Sowing Dates

Variations in the sowing date of chia (Salvia hispanica L.) reflect directly on the physiological potential of the produced seeds. This study aimed to analyze the yield and the physical and physiological quality of seeds from the main stem and branches of Salvia hispanica plants grown at different sowing dates. A field experiment was conducted in the crop year of 2016/2017 in five sowing dates (16/09/22, 16/10/28, 17/01/03, 17/02/08 and 17/03/24) in a randomized complete block design with four replicates. Harvest at each sowing date was done when 80% of the leaves of each plant exhibited a darker color, indicating that they were dry. Seed yield was determined in each plant compartment (main stem and branches) and final ear length (cm) and diameter (cm) were also measured at all sowing dates. The following physical and physiological tests were performed to determine seed quality: water content, mass of one thousand seeds, germination test, first count germination, length (root and hypocotyl) and dry matter of the seedlings. Chia can be sown from September to February providing seed yield with high physical and physiological quality. The physical and physiological quality of the chia seeds does not differ between main stem and branches. In late sowing, there is the risk of frost occurrence what may impair the physiological quality and the yield of chia seeds. The best sowing month for obtaining higher yield of chia seeds in a south subtropical region is January.

Site‐Specific Covariates Affecting Yield Response to Nitrogen of Late‐Sown Maize in Central Argentina

Core Ideas We used linear mixed effects models to explore maize yield response to applied N. Final models accurately described the observed data (R2 = 0.93). Best models indicated that yield response to applied N depended on soil N and soil type. Information is useful to optimize management decisions on N fertilizer rates. Resulting models are better than traditional ones based on ordinary least squares. Optimizing fertilizer rates is a common problem in modern agriculture. Frequently used response models ignore basic statistical assumptions and do not allow quantifying the effects of variables influencing yield response to fertilizer, generating uncertainty in fertilizer rate recommendations. We used linear mixed‐effects models to explore maize (Zea mays L.) yield response to applied nitrogen (N) in late sowings, and we tested different predictors for explaining yield responses across sites. Data included yield response trials to applied N at 17 different environments (combination site × year) with four to five N rates replicated twice in each trial. The best model (Model A) that included significant effect of N rate applied, sowing date, and soil N‐NO3 at sowing described grain yield variations with high accuracy (R2 = 0.93). Another best model (Model B) showed that soil type as additional variable affected significantly yield response to applied N. The final model indicated that the overall response across sites was characterized by a linear coefficient of 67 kg grain ha−1 per additional kg N ha−1 applied and a quadratic coefficient of −0.37 kg grain ha−1 per additional kg N ha−1 applied. Across all sites, soil N‐NO3 at sowing (explored range from 34 to 356 kg N ha−1) explained 46% of the variability in the linear yield response to applied N. We proposed a method and generated statistical models with site specific covariates that can help optimize farmers’ decisions on the use of optimal N fertilizer rates.

The effect of sowing date and plant density on the yield of maize (Zea mays L.) under different weather conditions

Maize has high productivity and produces huge vegetative and generative phytomass, but this crop is very sensitive to agroecological (mainly to climatic, partly to pedological conditions) and agrotechnical circumstances. In Hungary, maize is grown on 1.1–1.2 million hectares, the national average yields vary between 4–7 t ha-1 depending on the year and the intensity of production technology. The longterm experiment was set up in 2015–2016 on chernozem soil in the Hajdúság (eastern Hungary). The maize research was set up on chernozem soil at the Látókép MÉK (Faculty of Agricultural and Food Sciences and Environmental Management) research area of the University of Debrecen. We examined the following commonly used hybrids of Hungary: SY ARIOSO (FAO 300), P9074 (FAO 310), P9486 (FAO 360), SY Octavius (FAO 400), GK Kenéz (FAO 410), DKC 4943 (FAO 410). The experiment was set up in three different plant densities. These were 60, 76, 90 thousand plant ha-1. The experiment was set up with three different sowing dates, early, average and late sowing. The yield was measured using a special plot harvester (Sampo Rosenlew 2010), measuring the weight of the harvested plot and also taking a sample from it. As a next step, we calculated the yield (t ha-1) of each plot at 14% of moisture content to compare them to each other. We evaluated the obtained data using Microsoft Excel 2015.

Appraisal of optimal sowing time based on heat indices and row spacing for summer guar [Cyamopsis tetragonoloba (L.) Taub.

A field experiment was conducted during summer seasons of 2013 to 2015 on clayey soil of Junagadh (Gujarat) to ascertain proper time of sowing (4th week of January, 2nd week of February and 4th week of February) and spacing (30 x 15 cm, 45 x 15 cm and 60 x 15 cm) in relation to growth and yield of guar [Cyamopsis tetragonoloba (L.) Taub.]. The results revealed that sowing in 2nd week of February enhanced growth and yield attributes viz., plant height, pods per plant and test weight and ultimately gave higher seed yield (1387 kg/ha) and stalk yield (2846 kg/ha) with higher growing degree days (GDD), helio thermal units (HTU), photo thermal units (PTU) and heat use efficiency (HUE) as well as higher net returns (Rs. 42, 051/ha) and B: C ratio (2.29) over early (4th week of January) and late (4th week of February) sowing. The results further indicated that 45 x 15 cm spacing promoted growth and yield attributes viz., plant height, branches per plant, pods per plant and test weight compared to 30 x 15 cm and 60 x 15 cm, which reflected in higher seed yield (1272 kg/ha) and stalk yield (2680 kg/ha) along with higher net returns (Rs. 37, 154/ha) and B: C ratio (2.03) over 30 x 15 cm and 60 x 15 cm spacing. Therefore, sowing in 2nd week of February (when soil temperature >22.3oC at 5 cm and >23.9oC at 10 cm depth) and spacing of 45 x 15 cm could be appropriate for maximizing yield and monetary returns from summer guar under south Saurashtra agro-climatic conditions of Gujarat.