RESPONSE AND GROWTH OF SOME MAIZE VARIETIES (Zea mays L.) AT VARIOUS KNO 3 CONCENTRATIONS

This study aimed to determine the interaction effects of several maize varieties and KNO 3 concentrations on maize production. The research was carried out from December 2020 to April 2021 at the Indonesian Cereal Research Institute Facility, Bajeng District, Gowa Regency, South Sulawesi (5°18'21.5"S, 119°28'38.6"E). The study was designed using a split-plot experimental design, where the main plot was variety (V) which consisted of 4 varieties V1 (NASA-29), V2 (JH-37), V3 (BISI-2), and V4 (Pioner P-35). The subplots were KNO 3 (K) concentration which consisted of 4 concentrations, namely Control (K0), 2.5 g . L – 1 (K1), 5 g . L – 1 (K2), and 7.5 g . L – 1 (K3). Observational data were processed using ANOVA, and if there was a significant difference in the treatment, it was further tested with a 0.05 LSD follow-up test. The results showed that the JH-37 variety gave the best response, such as plant height, cob length, and production. The 7.5 g . L – 1 KNO 3 concentration gave the highest effect on all parameters of maize production; The interaction between the JH-37 variety with 7.5 g . L – 1 KNO 3 concentration gave the highest maize production; Parameters that have a positive correlation with maize productivity are expressed by plant height and weight of 1000 seeds.


INTRODUCTION
Maize (Zea mays L.) is one of the crops other than rice and wheat that are almost consumed by most of the population in various parts of the world. Data from Ministry of Trade Indonesia (2018) show that the national demand for maize reaches 15.50 million tons of dry shelled maize. Increment of maize production can be done with several methods, one of which uses hybrid varieties that have been proven to increase production, which is also supported by external factors such as fertilization to meet plant nutrient needs.
Potassium nitrate (KNO3) is a unique K source because of its nutritional value (it contains 38% K and 13% N) (El-Lethy, Abdelhamid, & Reda, 2013) and higher solubility in warm conditions (Singh, Singh, & Reddy, 2002). This fertilizer is also helpful to increase stem strength, prevent flower loss, improve fruit quality, and serve as a counterweight the excess nitrogen (Foth & Adisumarto, 1994). The KNO3 fertilizer is better to use than ZA or urea fertilizer because it can reduce soil pH and increase seedling height, leaf length, and the formation of leaves and roots numbers (Widiastoety, 2007).
In addition to fertilization, using suitable varieties also will increase maize production. Variety is one of the many determining factors in plant growth and yield. In addition to environmental factors, high-yielding varieties are an essential technology component to achieve high production. Some of the maize varieties that have been cultivated include Sukmaraga, Lamuru, Bisi 18, Pioner, BISI 2, and Bima (Sutresna, Aryana, & Gunartha, 2018) Research on the application of KNO3 on hybrid maize varieties has not been done much because KNO3 is more often used for horticultural crops or vegetable cultivation. Therefore, there are still vast opportunities for the use of KNO3 fertilizer in the food crops such as maize. Based on the description above, the authors are interested in conducting research to determine the growth and production of various maize varieties using various KNO3 fertilizer concentrations.

Methods
Land preparation was carried out with perfect tillage using a tractor, with a bed size of 4 × 5 with 1 meter between replicates. Maize seeds were planted at 75 × 20 cm. Planting holes were made individually; one hole was filled with one maize seed. Fertilizers used with recommended doses are Urea 300 kg.ha -1 , and NPK 350 kg.ha -1 as basic fertilizer. Meanwhile, the concentrations of KNO3 were 2.5 g.L -1 , 5 g.L -1 , and 7.5 g.L -1 . Spraying of KNO3 was carried out on plants aged 10 DAP, 20 DAP, 30 DAP, 40 DAP, and 50 DAP. Weeds and Pests that exist should be cleaned so that the nutrients in the soil are not divided into other plants. Weeding was done when the plants are 1-4 weeks old. Harvesting was done when the plant shows physiologically ripe signs. This sign was indicated by morphological characteristics, namely the leaves have started to turn yellow, the cob was yellowish-green, and the cob hair was brown, which was done manually by taking the maize cobs on each plant by turning the cobs with the cob, or it can also be done by broke the maize stalk which indicated by a black layer on the backside of the seed.

Study Area
This research was conducted at the Indonesian Cereal Research Institute Facility, Bajeng District, Gowa Regency, South Sulawesi Province (5°18'21.5"S, 119°28'38.6"E) at an altitude of 27.2 meter above sea level. This research took place from December 2020 to April 2021.

Data Analysis
Data were analyzed using an ANOVA, and if there was a significant difference in the treatment, it was further tested with a 0.05 LSD test. Observational data were analyzed using correlation analysis using Microsoft Office Excel.

Plant Height
The results of ANOVA showed that the interaction between maize varieties and KNO3 concentration had a significant effect on plant height. Based on the 5% LSD test, it can be seen that the interaction between the JH-37 (V2) variety with 7.5 g.L -1 KNO3 concentration (K3) has the highest plant height (201.13 cm), while the interaction between the NASA-29 variety (V1) with 7.5 g.L -1 KNO3 concentration of (K3) resulted to the shortest plant height (175.80 cm).
The use of high concentrations of KNO3 gave different results to the NASA-29 and JH-37 varieties. This proves that genetic characters in each variety give different responses to the given KNO3 concentration level. In KNO3 fertilizer, nitrogen (N) and potassium (K) are essential elements for the plants. An optimal nitrogen dose will increase plant growth, while lack of nitrogen will decrease plants growth, and excess nitrogen will make plants easily fall (Syafruddin, 2015).

Cob Height
The results of ANOVA showed that the maize variety had a significant effect on cob height, while there was no significant interaction between the maize variety and the KNO3 concentration. The BISI-2 (V3) variety cob height shows the highest (94.70 cm from the ground surface), while the lowest cob height from the ground is the P-35 (V4) variety (80.73 cm). The tendency of cob height is influenced by plant height in each variety which is used as one of the factors for providing nutrients to affect plant height increment. Wardani (2009) expressed the same phenomena, stating that the taller the plant, the higher the cob. The numbers followed by the same letter in the main plot column (a, b), and subplot column (p, q) mean that they are not significantly different in the LSD α = 0.05 test. The numbers followed by the same letter in the main plot column (a, b, c) means that they are not significantly different in the LSD α = 0.05 test.
The results in Table 3 show that the denser the stomata resulted in more stomata. The stomata function as a gas exchange for photosynthesis (Harrison, Cubas, Gray, & Hepworth, 2020). Stomata are closely related to the rate and intensity of transpiration in leaves. According to Passioura and Sflrzaker (1993), more pores on the leaf resulted in faster evaporation. If the holes' gaps are close, then evaporation from one hole will inhibit the evaporation of the nearby hole.
The lack of nitrogen supply in maize plants can also affect the amount of chlorophyll in plants so that the rate of photosynthesis becomes less optimal. It was also found in the research of Mu, Chen, Chen, Yuan, and Mi (2016) that nitrogen deficiency will reduce the Fakultas Pertanian -Universitas Ichsan Gorontalo Jurnal Agercolere Vol. 4(1) 2022, 28-34 amount of chlorophyll in the leaves, which leads to the photosynthesis rate decrease.

Cob Length
The ANOVA result in table 4 showed a significant interaction between maize varieties and KNO3 concentration to the cob length. The results found that the longest cob length resulted from the interaction between Varieties JH-37 (V2) with a 2.5 g.L -1 KNO3 concentration (K1) (20.87 cm).
The combination of maize varieties in accordance with the required nutrient resulted in the optimal length of the cob. This agrees with These results were closely related to findings of Oktem and Oktem (2005) who observed that increasing fertilizer concentration, will increased cob length, cob diameter and grains per cob. The numbers followed by the same letter in the main plot column (a, b), and subplot column (p, q) means that they are not significantly different in the LSDα = 0.05 test. The numbers followed by the same letter in the main plot column (a, b), and subplot column (p, q) means that they are not significantly different in the LSDα = 0.05 test.

1000-Grain Weight
Analysis of variance showed that there was an interaction between the maize variety and KNO3 fertilizer concentration on the parameter weight of 1000 seeds. In table 5, the 1000-grain weight parameter shows the interaction between varieties BISI-2 (V3) with 5 g.L -1 KNO3 concentration (K2) with an average of 300.71 g. Genetic characters in varieties that match the right nutrient concentration can make the weight of each maize kernel fuller, and large or dense so that it can contribute to the weight of yield per plot and productivity. This is in line with Ferayanti and Idawanni (2021) opinion that the difference in 1000 grain weight is closely related to the characteristics of each variety related to its ability to absorb nutrients during its growth period. The increase in 1000 grainweight is also related to the magnitude of photosynthate translocation into the seeds and the plant root system's ability to absorb nutrients from the soil.

Analysis
of variance in Table  6 showedsignificant interaction between maize varieties and KNO3 concentration on productivity parameters. The productivity parameter shows that the interaction between the JH-37 (V2) variety with 7.5 g.L -1 KNO3 concentration (K3) produces the best average productivity (9.32 t.ha -1 ), for the lowest productivity result is the interaction between the NASA-29 variety (V1) with 2.5 g.L -1 KNO3 concentration (K1) with average productivity of 6.13 t.ha -1 . This is in accordance with the result of Pangaribuan et al. (2017) which stated that KNO3 fertilizers can increase maize productivity. The numbers followed by the same letter in the main plot column (a, b), and subplot column (p, q) means that they are not significantly different in the LSDα = 0.05 test. The numbers followed by the same letter in the main plot column (a, b), and subplot column (p, q) means that they are not significantly different in the LSDα = 0.05 test. The application of KNO3 has an important role in increasing production because the element KNO3 contains potassium, which helps form leaves so that plants can maximize their production. This phenomena is in accordance with Hussain et al. (2015) that potassium fertilization can improve physiological traits resulting in increased production.
Characters that have a positive correlation with production are the character of plant height and weight of 1000 seeds. Plant height can maximize the absorption of sunlight to maximize seed production. This is in accordance with Herawati and Efendi (2017), which states that higher plants can absorb more sunlight, resulting in a higher photosynthesis rate, leading to increment seed yield and translocation for seed formation in the generative phase. While the positive correlation between the character of the 1000grain weight with productivity is also found in the research of Mohsin, Ahmad, Farooq, and Ullah (2014), that stating character the 1000grain weight have significant correlation with productivity.

CONCLUSION
We concluded that the JH-37 variety gave the best response to plant height parameters, cob length and production. The 7.5 g.L -1 KNO3 concentration gave the highest effect on all parameters of maize production. The interaction between the JH-37 variety with 7.5 g.L -1 KNO3 concentration gave the highest maize production. Parameters that positively correlate with productivity are plant height and 1000-grain weight.