Nitrogen and plant density effects on growth, yield performance of two different cotton cultivars from different origin

1 Introduction

Cotton is a most important worldwide cash crop that is grown up commercially for agricultural and industrial objectives in the temperate and tropical regions of approximately fifty countries (Smith, 1999). Even though cotton is primarily grown for fiber but it has several valued uses as its seed contains of 25.4% crude oil, 16.5% protein and 30% starch (Cobley, 1976). It plays a significant role in the country’s economy because of its high quality fiber (Rehman et al., 2015; Tausif et al., 2018; Ma et al., 2020). Pakistan is the second major exporter of raw cotton, the fourth leading grower of cotton, and the third biggest user of cotton in the world. Cotton is cultivated on an area of about 2.63 Mha in Pakistan comprising of total seed cotton fabrication of 10.98 million bundles. Cotton represents 40% in employment, 7% of the esteem in agriculture, and 60% in foreign exchange earning, 64% source of edible oil and about 1.4 percent to GDP (Government of Pakistan, 2010). Additionally cotton provides raw materials to the local industries comprising of 396 textile mills, 960 ginning factories, 9.7 million spindles and over 2622 oil expelling units (Anonymous, 2011). Cotton is considerably penetrating to environment circumstances and cultivated in a wide scope of ecological areas. A number of factors such as nature of cultivars, plant density, and nutrients management are involved in getting a profitable yield (Ali et al., 2005; Yang et al., 2014; Hafeez et al., 2019).

Nitrogen is a crucial nutrient for plant growth and development (Shah et al., 2017a). Application of chemical fertilizers has played a pivotal role in increasing crop production all over the world (Iqbal et al., 2021). Consequently, the use of N fertilizers increased many fold since their introduction in the late fifties (Ahmad, 2000). It is extensively renowned that N produces a remarkable effect on vegetative and reproductive growth. The excessive N can reduce harvesting and ginning percentage, promote boll shedding, diseases, insect damage and also delay maturity (Thind et al., 2008; Shah et al., 2021). However, low N is reduces leaves size, increase root shoot ratio, improved earliness and superior shedding percentage (Radin and Manney, 1986; Shah et al., 2017b). Thus, an adequate supply of N is associated with high photosynthetic activities, vigorous vegetative growth and a dark green color (Shah et al., 2017b).

Plant population is another important factor affecting cotton yield and its associated characteristics (Yang et al., 2014). Past studies have looked at the effects of variable cotton populations on yield and fiber quality, and have reported that optimal plant populations may vary from environment to environment. Dense populations include overgrown shades of plants, which lead to fruit decay, fruit absorption, plant height increase and delayed maturation, resulting in a decline in yield and fiber quality (Bednarz et al., 2005; Siebert and Stewart, 2006). While reducing seeding rates may reduce input costs, maturity, fluff yield and fiber quality may be negatively affected when the plant quantity is too low (Siebert and Stewart, 2006). Therefore, optimal plant populations are another key factor in sustainable cotton production (Shah et al., 2021). However, over the past few years, fertilizer prices in most developing countries, including Pakistan, have reached unprecedented lying highs and supply is limited when they are most needed. In most developed countries, N is sufficient as a fertilizer supply.

Beside this, there is no extensive research in Pakistan on high planting density in cotton. Few researchers conducted some experiments about ultra narrow rows in cotton but generally these are not being adopted under field conditions by farmers. But no one has investigated the interactive effect of N and PD research in Pakistan. Furthermore, fertilizer input losses are maximum due to excessive rains in Pakistan during the end of August and whole September. However, the problems could be solved by the new planting system which results in no yield reduction if the fertilizer is applied once at the appropriate time when the plant requires it most with high plant density in late sown cotton. Therefore it is also necessary to test the china’s hypothesis in Pakistan for the betterment of researchers and farmers. The objectives of this study were (i) to determine the response of cotton cultivars to N and PD on plant growth and seed cotton yield, (ii) to find out most appropriate combination of N and PD in Chinese and Pakistani cotton cultivars.

2 Materials and methods

3 Results

3.4

3.4 Cotton total nitrogen contents

Different PD and N application rate were considerably influenced on cotton N contents. Interaction of PD and N application rate showed higher contents in FH-142 under F2with medium plant density at different DAE which followed by F1 with high plant density (Fig. 1a). On the other hand, least N contents in FH-142 were observed under F1 with low plant density in all DAE. Nonetheless, Huamian-3109 was affected considerably at different DAE with higher N contents under F1 with high plant density followed by F2 with medium plant density, while least N contents were observed in F1 with low plant density in all DAE (Fig. 1b).

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Fig. 1a

Interactive effects of planting density and nitrogen application rate on total nitrogen contents of FH-142. Mean values with in a column followed by the same letters are not significantly different at P < 0.05 according to significance difference test (LSD).

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Fig. 1b

Interactive effects of planting density and nitrogen application rate on total nitrogen contents of Huamian-3109. Mean values with in a column followed by the same letters are not significantly different at P < 0.05 according to significance difference test (LSD).

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4 Discussion

From our previous findings we found that F1 (120 kg ha⁻¹) with HPD (12 plants m⁻²) and/or F2 (180 kg ha⁻¹) with MPD (10 plants m⁻²) are more productive combination of N and PD in China (Shah et al., 2017a). This study was conducted in the subtropical climatic conditions of Pakistan and a Chinese cultivar (Huamian-3109) was compared with a Pakistani cotton cultivar (FH-142) to further optimize PD and N fertilizer rate and to examine any effect of experiment location on the treatments of different cotton cultivars from different origins.

Cotton phenology in both cultivars was varied under different PD and N application rate. Cotton cultivar FH-142 took 43 to 47 days to complete seedling stage while Huamian-3109 completed seedling stage in range of 47 to 58 days (Table 2) respectively. In contrast, FH-142 took 30–36 days to complete squaring stage after seedling stage while Huamian-3109 took 27–28 days to complete squaring stage. We further noted that though Huamian-3109 took more days and produced more number of squares plant⁻¹ however square shedding rate much higher (data not shown) as compared to FH-142. For boll setting stage, a non-considerable interaction effect of PD and N application rate was found in FH-142 while Huamian-3109 was considerably influenced for boll setting stage. Overall results pertaining to total crop duration showed that, Huamian-3109 took less number of days to reach maturity as compared with FH-142. Although boll setting was unaffected by PD and N application rate in FH-142, however this cotton cultivar took more number of days for boll setting as compared to Huamian-3109, therefore FH-142 produced more number of bolls m⁻² and seed cotton yield as compared to Huamian-3109. Our results further supported by the previous study that cotton plant acquired less number days for squaring while took more number of days to complete blooming to boll setting (Shah et al., 2017a, 2021).

Nonetheless, in other studies Bednarz et al. (2006); Dong et al. (2010) demonstrated that high plant population reduced boll weight but enhanced boll numbers per unit area, and therefore increased lint yield in short season cotton. This could be associated with limiting the development of outer bolls and improving boll distribution (Gwathmey and Clement, 2010). However, there was no significant increase in lint yield at higher plant density (Bednarz et al., 2000–, 2003; Dong et al., 2010).

We found varied response of both cotton cultivars to the interaction effects of planting density and N application rate. Considerable interaction effects of different N levels and PD have been observed on number of fruiting branches plant⁻¹. A non-considerable effect of N and PD was noted on fruiting branches in Chinese variety while in Pakistani variety it was influenced considerably. Among cotton cultivars, FH-142 developed more leaf area, and exhibited more green leaves and total number of leaves as compared with Huamian-3109. Our results regarding the differential response of Chinese varieties from different origin are further supported that genetically varieties originated from different climates had quite different response to fertilizer levels for plant growth (Tomar et al., 2000; Walch-Liu et al., 2005).

Furthermore Pakistani variety (FH-142) among treatments showed higher SPAD value, and leaf area in F1with HPD or F2with MPD while plant dry biomass production in F2 with MPD followed by F1with high PD. This may be due to the better translocation and distribution of N in cotton plants, so cotton growth increases compared to other treatments (Dai et al., 2015). Difference among cotton cultivars regarding growth and yield response was due to genetic makeup and could be due to weather conditions. Temperature regimes at this experimental site could also influence the performance of Huamian-3109 as compared to FH-142. Temperature provides the energy for crop plant to adjust the activities of enzymes and trigger corresponding bio-reactions of energy and material conversion such as photosynthesis (Yang et al., 2014). Crop varieties with lower canopy temperature had a higher yield resulted from slower declining tendency in chlorophyll and soluble protein in cotton.

N application rates and PD were significantly influenced on yield and yield traits. Moreover, both cotton cultivars performed variedly under different treatments, FH-142 produced higher seed cotton and lint yield compared to Huamian-3109 under F2with MPD followed by F1 with HPD. Nonetheless, Huamian-3109 produced higher seed cotton and lint yield under F1 with HPD and F2 with MPD as compared to other treatments. Higher seed cotton yield and lint yield was due to development of more number of bolls plant⁻¹ with high boll weight (Aslam et al., 2013; Rochester et al., 2001).

Our results further justified by other studies; both PD and N fertilization rate showed effects on biomass formation of cotton plants and thereby increase cotton yield and nitrogen efficiency (Dai and Dong, 2014). An adequate increase in plant density can also increase seed cotton yield and N efficiency (Dong et al., 2010; Mao et al., 2014). Nonetheless, some studies contradicted that increased in N rate reduce the lint percentage by 0.16%, while increase in boll weight may be due to increase in N rate with current increase in mineral uptake, photosynthetic assimilation and accumulation in sinks (Sawan et al., 2006). Among cotton cultivars FH-142 produced more seed cotton yield and lint yield as compared with Huamian-3109 and the difference was due to variation in the phenology of cotton (Table 2). Cotton fiber quality and related traits were significantly influenced by N application rate and PD (Table 7). Moreover, N application considerably influenced cotton fiber yield and quality, suggesting N as key factor that influence fiber quality considerably (Chen et al., 2016). This is in agreement with others who observed reduced micronaire values with increase in plant density (Bednarz et al., 2005). Bednarz et al., (2003) documented that smaller bolls end to contain smaller seeds with less weight of fibers per seed. Thus, altered within-boll yield components through increased plant density may also affect micronaire.

Different PD and N application rate were considerably influenced on cotton total N contents. Interaction effects of PD and N application rate showed higher N contents in FH-142 under F2 with MPD at different DAE, (Fig. 1a). Total N contents were affected considerably in Huamian-3109 at different DAE showed higher N contents under F1 with HPD at different DAE, (Fig. 1b). Least N contents were observed in F1 with LPD under both cotton cultivars at different DAE. Similar results have been reported that with different planting density, cotton optimizes photosynthetic N use efficiency and photosynthetic capacity by adjusting leaf mass per area, which in turn affected leaf N allocation to the photosynthetic apparatus. However MPD is the optimum PD due to high light utilization efficiency, superior spatial distribution of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N in leaves within the canopy (Yao et al 2015). Higher yield under MPD could be attributed to an optimal leaf area and increased light interception (Kaggwa-Asiimwe et al., 2013).

5 Conclusions

This study shows that interaction effects of N application rate and PD on growth, yield and N contents in two cotton cultivars. We found that among cotton cultivars, FH-142 (Pakistani variety) performed better as compared with Huamian-3109 (Chinese variety). Among treatments, FH-142 produced high seed cotton and lint yield under MPD (10 plants m⁻²) with F2 rate (180 kg ha⁻¹) while Huamian-3109 produced higher seed cotton yield and lint yield under HPD (12 plants m⁻²) with F1 (120 kg ha⁻¹) and under MPD (10 plants m⁻²) with F2 rate (180 kg ha⁻¹). So this study confirmed and recommended above mentioned N application rate and PD for better growth and yield performance of both Pakistani and Chinese cotton cultivar.

Funding

The National Natural Science Foundation of China was supported and provided funds for this project 31271665.