Late Sowing Research Articles

Increased age at first-mating interacting with herd size or herd productivity decreases longevity and lifetime reproductive efficiency of sows in breeding herds

BackgroundOur objectives were to characterize sow life and herd-life performance and examine two-way interactions between age at first-mating (AFM) and either herd size or herd productivity groups for the performance of sows. Data contained 146,140 sows in 143 Spanish herds. Sow life days is defined as the number of days from birth to removal, whereas the herd-life days is from AFM date to removal date. Herds were categorized into two herd size groups and two productivity groups based on the respective 75th percentiles of farm means of herd size and the number of piglets weaned per sows per year: large (> 1017 sows) or small-to-mid herds (< 1017 sows), and high productivity (> 26.5 piglets) or ordinary herds (< 26.5 piglets). A two-level liner mixed-effects model was applied to examine AFM, herd size groups, productivity groups and their interactions for sow life or herd-life performance.ResultsNo differences were found between either herd size or herd productivity groups for AFM or the number of parity at removal. However, late AFM was associated with decreased removal parity, herd-life days, herd-life piglets born alive and herd-life annualized piglets weaned, as well as with increased sow life days and herd-life nonproductive days (P < 0.05). Also, significant two-way interactions between AFM and both herd size and productivity groups were found for longevity, prolificacy, fertility and reproductive efficiency of sows. For example, as AFM increased from 190 to 370 days, sows in large herds decreased herd-life days by 156 days, whereas for sows in small-to-mid herds the decrease was only 42 days. Also, for the same AFM increase, sows in large herds had 5 fewer sow life annualized piglets weaned, whereas for sows in small-to-mid herds this sow reproductive efficiency measure was only decreased by 3.5 piglets. Additionally, for ordinary herds, sows in large herds had more herd-life annualized piglets weaned than those in small-to-mid herds (P < 0.05), but no such association was found for high productivity herds (P > 0.10).ConclusionWe recommend decreasing the number of late AFM sows in the herd and also recommend improving longevity and lifetime efficiency of individual sows.

PERFORMANCE OF MAIZE CROSSES UNDER LATE PLANTING CONDITION

A field experiment was carried out to evaluate the performance of seven white maize hybrids under late planting condition with respect to yield and grain quality during the two successive seasons of 2017 and 2018. The experimental design was laid out using randomized complete block design with four replicates. Maize hybrids were significantly differed in all traits studied in both seasons, except grain oil percentage. The variety S.C 128 exhibited the highest days to maturity, while the lowest ones was T.W.C 321 in both seasons as compared with other tested hybrids. The variety T.W.C 321 significantly surpassed other tested hybrids in mean values of grain yield /fed and relative grain yielding ability, while T.W.C 324 and T.W.C 329 gave the lowest mean values in both seasons. Concerning grain quality, S.C 131 and S.C 2031 recorded the highest mean values of oil yield/fed, Meanwhile, T.W.C 321 and S.C 2031 surpassed the other hybrids in mean values of protein percentage and protein yield/fed in the both seasons. It could be summarized that the best hybrid was T.W.C 321 when planting maize in late sowing, where it produced grain yield more than other S.C 131, S.C 2031, S.C 10, S.C 128, T.W.C 324 and T.W.C 329 hybrids by 2.74, 3.08, 4.85, 4.89, 21.40 and 24.96%, respectively as an average of both seasons.

One-time fertilization at first flowering improves lint yield and dry matter partitioning in late planted short-season cotton

Cotton producers have substantially reduced their inputs (labor, nutrients, and management) mainly by adopting a short-season cropping management that is characterized by late sowing, high density, and reduced fertilization with one-time application at the first bloom stage without lint yield reduction. However, it has been hypothesized that one-time fertilization at an earlier growth stage could be a more effective and economic management practice. A two-year field experiment was conducted by applying five fertilizer one-time fertilization at 0 (FT1), 5 (FT2), 10 (FT3), 15 (FT4), and 20 (FT5) days after the first flower appeared in the field and one three-split fertilizer application taken as the conventional control (FT6), making six treatments altogether. Cotton growth period, biomass accumulation, yield, and its formation were quantified. The results showed that the one-time fertilization did not affect the cotton growth progress as compared to FT6, however, the total crop cycles for FT3–FT5 were 3 days shorter. FT1 produced the highest cotton lint yield (1 396 kg ha−1), which was similar to the FT6 but higher than the other treatments, and could be attributed to more bolls per unit area and higher lint percentage. Cotton yield was positively correlated with cotton plant biomass accumulated. FT1 had both the highest average (VT) (193.7 kg ha−1 d−1) and the highest maximum (VM) (220.9 kg ha−1 d−1) rates during the fast biomass accumulation period. These results suggest that one-time fertilizer application at the first flower stage might be an adjustment that is more effective than at first bloom, and allowed for easier decision making for application date due to non counting of plants with flowers is needed.

Equal K Amounts to N Achieved Optimal Biomass and Better Fiber Quality of Late Sown Cotton in Yangtze River Valley

Potassium (K) fertilizer plays a crucial role in the formation of the biological and economic yield of cotton (Gossypium hirsutum L.). Here we investigated the effects of the amount of K on biomass accumulation and cotton fiber quality with lowered N amounts (210 kg ha−1) under late sowing, high density and fertilization once at 2 weeks after squaring. A 2-year field experiment was performed with three K fertilizer amounts (168 kg ha−1 (K1), 210 kg ha−1 (K2), and 252 kg ha−1 (K3)) using a randomized complete block design in 2016 and 2017. The results showed correspondingly, K3 accumulated cotton plant biomass of 7913.0 kg ha−1, next to K2 (7384.9 kg ha−1) but followed by K1 (6985.1 kg ha−1) averaged across two growing seasons. Higher K amounts (K2, K3) increased biomass primarily due to a higher accumulation rate (32.68%–74.02% higher than K1) during the fast accumulation period (FAP). Cotton fiber length, micronaire, and fiber strength in K2 were as well as K3 and significantly better than K1. These results suggest that K fertilizer of 210 kg ha−1 should be optimal to obtain a promising benefit both in cotton biomass and fiber quality and profit for the new cotton planting model in the Yangtze River Valley, China and similar climate regions.

Soybean (Glycine max (L.) Merr.) Yield Reduction due to Late Sowing as a Function of Radiation Interception and Use in a Cool Region of Northern Japan

Yields decrease when soybean is sown later than recommended in the cool climate of the Tohoku region of Japan. However, the factors responsible for this decrease are not fully understood. We investigated the effects of late sowing on growth, phenological development, yield, yield components, and radiation interception of three soybean cultivars in two consecutive years and analyzed the relationships of those variables with temperature and soil volumetric moisture content (SMC). Averaged across years and cultivars, yields decreased significantly when plants were sown approximately three weeks late. Yield reductions were partially due to reductions in node number per plant, dry matter production, and capture of cumulative irradiance, resulting from slowed canopy development during vegetative and early reproductive stages. The number of seeds per pod was one of the major determinants of the variation in yield. Owing to the delay in sowing date, the reduction in seeds per pod was likely due to low temperatures during the 20 days after seed filling began. Occasional lower SMC during reproductive stages did not affect yield, yield components, and growth parameters. However, these results were obtained from the two years’ experiments. Therefore, further investigations of the relationship of yield with temperature and SMC under different years and sites are needed.

Sucrose Metabolism and RUBISCO Activity Influenced by Salicylic Acid at Flowering Stage Revealed Tolerance to Heat Stress in Chickpea Genotypes

The heat tolerant (ICC-4958, GG-2) and susceptible (ICC-4567, GJG-5) chickpea (Cicer arietinum L.) genotypes were studied for enzymes of sucrose metabolism and RUBISCO activity associated with reproductive collapse under the influence of salicylic acid (SA) during normal and late sowing. The RUBISCO (carbon fixing enzyme) and sucrose phosphate synthase (SPS) decreased significantly in tender leaves (nearer to flower) and anthers due to heat stress leading to reduced sucrose content in late sowing as compared to normal sowing in susceptible genotypes. The pollen length (SEM) of flower was reduced in susceptible genotypes correlating less sucrose and higher invertase activity under heat stress. The activities of RUBISCO, SPS and sucrose content were enhanced (4.31 and 3.29 fold) in susceptible genotypes by SA2 (200 ppm) compared to tolerant (2.17 and 2.31 fold) in leaves under heat stress. The invertase activity remarkably decreased in tolerant genotypes compared to susceptible under the influence of SA in leaves and anthers during late sowing. The leaves sucrose content were enhanced 3.48 fold in tolerant compared to 1.55 fold in susceptible genotypes by SA2. The improvement in reproductive failure due to heat stress (late sowing) was observed better in susceptible genotypes compared to tolerant after SA applications (200 ppm) at flowering stage which elevated enzymes of sucrose metabolism and RUBISCO activity. However, these enzymes found to be higher in tolerant genotypes as pre-existing mechanisms to boost up growth of reproductive organ. The RUBISCO activity, sucrose content and enzymes for sucrose metabolism were found higher in leaves (first tender leaves near to flower) compared to the anthers except SPS which was found higher in anthers particularly in tolerant genotypes during heat stress signifying source to sink transportation of sucrose during flower development and fertilization influenced by SA.

Effects of Late Sowing on Differentiation and Degeneration of Branches and Spikelets of &amp;lt;i&amp;gt;Indica&amp;lt;/i&amp;gt; Rice under Different Ecological Conditions

In rice (Oryza sativa L.), yield is related to characteristics of branches and spikelets. To investigate the effects of late sowing date on differentiation and degeneration of spikelets in rice, field experiments were conducted in Chongzhou and Hanyuan, China. Differentiation and survival of branches and spikelets in Hanyuan were lower than that of Chongzhou, whereas degeneration was greater than that of Chongzhou. In Chongzhou, sowing date affected differentiation and survival of primary, secondary, and total branches, as well as differentiation and degeneration of secondary and total spikelets. In Hanyuan, sowing date affected degeneration of secondary and total branches, and the survival and degeneration of primary spikelets. Late-sown plants experienced higher temperatures in the jointing to heading period, and there were higher sunshine hours. Rainfall and humidity were higher in Chongzhou, but lower in Hanyuan. Late sowing increased differentiation, degeneration, and survival number of branches and spikelets in Chongzhou. However, in Hanyuan, late sowing increased differentiation and degeneration of branches, but decreased survival of branches, which reduced spikelet differentiation and degeneration, resulting in fewer branches. Thus, the key to higher yield in Chongzhou was to increase differentiation of spikelets, whereas in Hanyuan, it was to reduce degeneration of branches and spikelets.

Gas exchanges and growth of soybean cultivars submitted to water deficiency

ABSTRACT A low availability of water in the soil may alter morphological traits and physiological processes in soybean, limiting its development, mainly at late sowings. This study aimed to evaluate the leaf gas exchanges and dry matter accumulation in soybean cultivars under low water availability at late sowing. An Oxisol with a very clayey texture was employed. A completely randomized design, in a 5 × 3 factorial scheme, with four replications, was used. The treatments were five water tensions (10 kPa, 15 kPa, 25 kPa, 40 kPa and 60 kPa) combined with three soybean cultivars (BRS Favorita, BRSMG 820 and BRSMG 850). The response variables were measured at 55 days after the emergence. The values for stomatal conductance, transpiration, photosynthesis rate, intercellular CO2 concentration and instantaneous carboxylation efficiency were significantly reduced (p &lt; 0.05) with the increase of the water tension in the soil. The gas exchanges in the soybean plants were also reduced with the increase of the water tension in the soil, being the most critical ones observed from 25 kPa. BRSMG 850 showed the best performance for production of root dry matter in this water tension in the soil.

Effects of late sowing of two season crops on annual yield and resource use efficiency in rice-wheat double cropping system

The unreasonable resource allocation and lower resource use efficiency for rice-wheat double cropping system in Jianghuai region resulted from climate change severely limit the coordinated development of annually high yield and high efficiency crops. Optimizing seasonal resource allocation through sowing date adjustment is an important way to tap the annual high-yield potential and improve resource use efficiency. To quantify the effects of sowing date of rice and wheat on annual yield and resource allocation and utilization efficiency, field experiments were conducted in 2013-2015. Results showed that compared with the conventional rice-wheat cropping system (T2), the two seasons appropriate late-cast cropping system (T3) could coordinate resource allocation in the two seasons through the sowing date adjustment, and transfer the redundant radiation and heat resources in the wheat season to the rice. The distribution rate of accumulated temperature, radiation and rainfall resources for T3 were: rice season accounted for 60.5%, 46.5% and 56.7%, wheat season accounted for 36.3%, 50.0% and 40.9%, and the ratio between two seasons was 1.67, 0.94 and 1.39, respectively. Rice yield and its proportion of annual production were significantly increased. The wheat yield was significantly decreased, with the variation range being smaller than that of rice. The total annual yield was increased by 336.3 kg·hm-2 as compared with T2. The temperature, radiation and rainfall production efficiency for rice in T3 were increased by 9.8%, 5.6% and 8.3% in compared to T2, respectively. There was no significant difference in the climate resource utilization efficiency of wheat season. The annual resource production efficiency of T3 was increased by 4.8%, 3.1% and 6.0% over the T2, respectively. Earlier (T1) or latest sowing (T4) of two seasons cropping system was not appropriate for annual yield formation and resource utilization. In summary, improving resource utilization efficiency in rice season is the key way to increase annual grain yield potential in Jianghuai region. The results provided theoretical and practical bases for the excavation of yield potential of the regional annual cropping system and the adjustment of planting structure.

A complex of breakthrough grain production technology

The massive introduction of foreign machinery, seeds, and technologies not adapted to Russian conditions over the past quarter-century have led agricultural production in Russia to reduce yield and quality of manufactured products. The reasons leading to the loss-making of Russian production are manifold, namely, over-compaction of fields with heavy equipment and small processing, excluding moisture absorption and moisture accumulation, destroying floods, artificial “drought, ” forced late sowing and ultra-expensive western equipment. This article is devoted to the description of a breakthrough proposal, which includes the creation of technology with a complex of domestic technology, which is costeffective and import-leading in all environmental, energy, and economic indicators. The research work is approved by many official scientific and technical councils and is a significant legitimate contribution to the development of agricultural machinery in Russia, increasing labor productivity in agricultural production and restoring the health of the nation. On the basis of domestic tractors of traction classes of 1.5-5.0 ts, a full range of functional agricultural equipment has been created that provides an increase in productivity, yield and its quality, profitability up to 2 times with a decrease in specific metal consumption, power, fuel consumption and cost growth from 2 to 4 time.

Tiller composition and dry matter production of late sowing of hulless barley (Hordeum vulgare var. nudum) var. Haruhimeboshi grown under different seeding amounts and split applications

Tiller composition and dry matter production of late sowing of hulless barley (<i>Hordeum vulgare</i> var. nudum) var. Haruhimeboshi grown under different seeding amounts and split applications

Overview of Epidemiology, Biology and Integrated Management of Chocolate Spot (&amp;lt;i&amp;gt;Botrytis fabae&amp;lt;/i&amp;gt;) of Faba Bean in Ethiopia

Chocolate spot is a serious disease that cause yield reduction on Faba bean crop, thus, effective management is essential. The objective of this review work was to review available to manage chocolate spot of faba bean with host resistance and fungicides. There are many biotic and abiotic factors which hampers Faba bean production in Ethiopia. From biotic factors chocolate spot (Botrytis fabae Sard.) is the major fungal disease hampering Faba bean production in Ethiopia.). It is a highly prevalent and destructive disease, causing yield loss up to 61% on a susceptible and 34% on tolerant Faba bean genotypes in the central highlands. But we can manage this economically important disease in manner which comprised by using different methods from these late sowing of Faba bean, mixed cropping of Faba bean with cereal crops, fungicides application and crop rotation were found better to reduce the disease and increased the grain yield. Therefore, use all available diseases management methods in combination that is IDM (Integrated Disease management) is better to reduce disease severity of chocolate spot.

Features of Germination of Flax Seeds under the Influence of Hypothermal Stress

Oil flax is a valuable and cost-effective agricultural crop, which is used in various industries. Flax is a relatively cold-resistant moisture-loving plant for a long day, so late sowing leads to a decrease in yield. Sowing in the “February-March windows” is the most economically feasible, but it is necessary to take into account sudden frosts, due to which crops shed or plants die. On different cultures it has been proven that a synergistic interaction of manganese, zinc and cuprum has a positive effect on cold resistance. The objective of this work was to establish the characteristics of seed germination of various genotypes of oil flax under the influence of hypothermic stress and to reveal the content of copper, manganese and zinc in the seeds on their cold resistance. The research material was the seeds of 5 genotypes of oil flax: Vodograi, A-11, B-11, Southern Night, Southern Altai. Determination of cold resistance was carried out by methods of cold germination of seeds and cold germination of seeds in the soil. The content of trace elements was determined by atomic absorption spectrophotometry with flame atomization. The article studies the change in the indicators of germination of oil flax seeds (germination energy, copper, manganese and zinc) under the influence of cold stress. Based on the difference in the values of moisture absorption activity between the experimental and control variants, we found that methods for assessing cold tolerance (cold germination of seeds and cold germination of seeds in the soil) are effective. It was established that genotypes resistant to hypothermia had a higher moisture content and higher water absorption during cold germination on filter paper and in the soil. The highest water-absorbing activity was of the Vodograi variety, samples A-11 and B-11 were slightly lower, the lowest was Southern Night and the lowest was Southern Altai. A positive effect of a high content of copper, manganese and zinc in dry flax seeds on the cold resistance was found. The highest micronutrient content, 91.6 mg / kg, was characterized by the cold-resistant variety Vodograi, and the lowest content was 68.6 mg / kg - the unstable variety Southern Altai.

Effects of different seeding amounts and nitrogen split applications on yield and quality of late sowing of hulless barley (Hordeum vulgare var. nudum) var. Haruhimeboshi

Effects of different seeding amounts and nitrogen split applications on yield and quality of late sowing of hulless barley (<i>Hordeum vulgare</i> var. nudum) var. Haruhimeboshi

Effect of Sowing Methods and Weed Management Practiced on Growth, Yield, Weed Flora and Nutrient Uptake on Late Sown Chickpea

Chickpea is highly sensitive crop to weed competition as early stage of growth. In the light of fragmental information available on the response of application of sequential application of herbicides under different sowing methods, a field experiment was conducted during winter season of 2013–14 to 2015–16. Results revealed that chickpea sowing in reduced tillage performed better and produced higher number of pods per plant, seed yield, protein yield and nutrient uptake over conventional tillage. In weed management treatment, sequential application of pendimethalin@0.75 kg a.i./ha pre-emergence followed by imezethapyr @40g a.i./ha post-emergence improve the crop growth and produced higher seed yield (1515 kg/ha), protein yield and nutrient uptake. Weed density and weed dry weight of different species were recorded minimum under reduced tillage at both 30 and 60 days after sowing. Application of pendimethalin @0.75kg a.i./ha pre-emergence followed by imezethapyr @40g a.i./ha post-emergence reduced theweed density and weed dry weight over other treatments and recorded minimum. Weed control efficiency recorded higher with conventional tillage (70.04%) and closely followed by reduced tillage (70.81%). Pendimethalin@0.75kg a.i./ha pre emergence fbimazethapyr @ 40g a.i./ha post-emergence recorded highest weed control efficiency (92.93%).

Impact of Foliar Application of Different Nutrient Sources on Yield of Chickpea under Late Sown Conditions

Impact of Foliar Application of Different Nutrient Sources on Yield of Chickpea under Late Sown Conditions

Genotype-environment interaction on stability of grain yield and physio-biochemical traits in bread wheat (Triticum aestivum L.)

To assess the stability of genotypes for grain yield and physio-biochemical traits associated with terminal heat tolerance pooled analysis of 8 genotypes of wheat of diverse origin, their 28 F1 progeny and 2 checks were carried out in 4 different environments i.e. early sown (E1), normal sown (E2), late sown (E3) and very late sown (E4) conditions. The pooled analysis of variance due to environment (for proline and chlorophyll content), genotypes and genotype × environment interaction was significant for all the traits under consideration. This indicated the distinct and differential effect of the different sowing conditions (environment) and differential response of all the genotypes chosen for the study. The five stable wheat hybrids viz., HI 1544 × HD 2987, Raj 4037 × HD 2987, PBW 175 × HD 2987, HD 2932 × Raj 4079 and PBW 175 × Lok 1 showed higher mean values, favourable regression coefficient and deviation from regression coefficient for grain yield and other associated characters, thus emerged as stable genotypes as per criteria of stability analysis. Similarly, some genotypes showed specific adaptations for poor or heat stress environment.

Triticale for late autumn sowing

Taking into account tendencies in climate changes towards continentality escalation, new ways to ensure stable production of food grain are searched for. Creation of triticale varieties with late sowing in autumn and early sowing in “February windows” (temporary thaws in February – at the early of March) is quite promising. This allows plants to effectively use soil moisture, stages of plant organogenesis occur earlier, and, as a result, crucial periods of the plant development do not coincide with the most intense droughts and take place at lower air temperatures.&#x0D; The aim of the research was to evaluate the yield capacity of triticale varieties and lines with late autumn sowing and to create wintering triticale lines with high grain yield and adaptability.&#x0D; Methods. Field (to study the interaction of the object of research with biotic and abiotic factors); biometric and weighing (to determine grain yield); statistical (statistical processing of research results).&#x0D; Results. The study on the productivity formation was carried out under late autumn sowing of triticale varieties and lines (the first decade of October) under conditions of Kharkiv region.&#x0D; The yields of spring triticale varieties under late autumn sowing averaged over the years amounted to 5.11–6.13 t / ha. Moreover, they formed a large filled grain (weight of 1,000 grains is 42.1–47.2 g). The best yield indicators by the years of research was showed by the variety Boryvіter Kharkivskyi– 6.13 t / ha, which exceeded the standard Korovai Kharkivsky by 1.02 t/ha.&#x0D; The highest yield under late autumn sowing was formed by two-handled cultivar Pidzymok Kharkivskyi and the line L5 (respectively 7.43 and 7.59 t/ha). They exceeded significantly the standard winter triticale variety Raritet by their yield (5.61 t/ha).&#x0D; As a result of the assessment, eight complex valuable triticale lines suitable for late autumn sowing (wintering lines) were identified: TKhZ 12p-19, TKhZ 15p-19, TKhZ 16p-19, TKhZ 31p-19, TKhZ 39p-19, TKhZ 66p-19, TKhZ 68p-19 and TKhZ 96p-19. The lines are characterized by increased productivity, well-filled grain (8–9 points), resistance to lodging (optimal height is 96–111 cm). According to the growing season they are early and mid-ripening. The lines are resistant to damage by loose and hard smut, powdery mildew and have increased resistance to damage by stem rust, leaf rust and leaf septoria (7–9 points). Increased adaptability of the lines is ensured by cold resistance and drought resistance. Therefore, they are the most promising for growing in arid steppe regions at late autumn and winter sowing.&#x0D; The use of triticale varieties and lines with increased productivity, resistant to lodging, suitable for late autumn sowing is important under conditions of increasing aridity of the climate and significant increase in the sowing area under row crops (corn, soybean, sunflower, etc.).

Phenology, Growth and Pod Yield of French Bean (Phaseolus vulgaris L.) as Influenced by Temperature Variations Under Different Sowing Dates

The experiment was conducted at the research field of the Agronomy Division, Bangladesh Agricultural Research Institute (BARI), Bangladesh during rabi season of 2017-2018 to evaluate the flowering behavior and pod yield of French bean. Three varieties namely BARI Jharsheem-1, BARI Jharsheem-2 and BARI Jharsheem-3 were sown on 30 November, 15 December and 30 December, respectively for getting temperature variation. Sowing dates based on temperature variation, significantly affect the flowering behaviour and pod yield of French bean varieties. Developmental events were badly affected when sown on 30 December. Crop accumulated lower GDD for different development events when sown late. Flowering duration of 30 November sowing were longer due to prevailing low temperatures (Min.10.3-11.4 °C and Max 23.7-24.5 °C) (Table 2). On the contrary, minimum flowering duration was recorded in 30 December sown crop (11-17 days). Minimum duration might be due to prevailing high temperature (Min.14.9-15.3 °C and Max 27.6-28.8 °C) that shorten the flowering duration of all French bean varieties. Pod yield of all the varieties were more at November sowing and decreased towards late sowing. November 30 sowing performed better in relation to yield components and yield which was very close to 15 December sowing. BARI Jharsheem-1 produced the highest pod yield (16.77t ha-1) in 30 November sowing. French bean had been sown on November to December showed the greater variability in respect of flowering, flowering duration and the number of pods. The results revealed that November would be the optimum sowing date (15 Nov.-30 Nov.) for maximum pod yield of french bean var. BARI Jharsheem-1&#x0D; Bangladesh Agron. J. 2018, 21(2): 25-32

Changes in Leaf Structural and Functional Characteristics when Changing Planting Density at Different Growth Stages Alters Cotton Lint Yield under a New Planting Model

Manipulation of planting density and choice of variety are effective management components in any cropping system that aims to enhance the balance between environmental resource availability and crop requirements. One-time fertilization at first flower with a medium plant stand under late sowing has not yet been attempted. To fill this knowledge gap, changes in leaf structural (stomatal density, stomatal length, stomata width, stomatal pore perimeter, and leaf thickness), leaf gas exchange, and chlorophyll fluorescence attributes of different cotton varieties were made in order to change the planting densities to improve lint yield under a new planting model. A two-year field evaluation was carried out on cotton varieties—V1 (Zhongmian-16) and V2 (J-4B)—to examine the effect of changing the planting density (D1, low, 3 × 104; D2, moderate, 6 × 104; and D3, dense, 9 × 104) on cotton lint yield, leaf structure, chlorophyll fluorescence, and leaf gas exchange attribute responses. Across these varieties, J-4B had higher lint yield compared with Zhongmian-16 in both years. Plants at high density had depressed leaf structural traits, net photosynthetic rate, stomatal conductance, intercellular CO2 uptake, quenching (qP), actual quantum yield of photosystem II (ΦPSII), and maximum quantum yield of PSII (Fv/Fm) in both years. Crops at moderate density had improved leaf gas exchange traits, stomatal density, number of stomata, pore perimeter, length, and width, as well as increased qP, ΦPSII, and Fv/Fm compared with low- and high-density plants. Improvement in leaf structural and functional traits contributed to 15.9%–10.7% and 12.3%–10.5% more boll m−2, with 20.6%–13.4% and 28.9%–24.1% higher lint yield averaged across both years, respectively, under moderate planting density compared with low and high density. In conclusion, the data underscore the importance of proper agronomic methods for cotton production, and that J-4B and Zhongmian-16 varieties, grown under moderate and lower densities, could be a promising option based on improved lint yield in subtropical regions.