BUKHARI. Resistance of Corn Varieties to Water and Nutrient Stress in Vegetative and Generative Growth Stages in Ultisol Dryland, under supervision of SABARUDDIN ZAKARIA, SUFARDI, and SYAFRUDDN.
Abiotic stress is a limiting factor in corn production on Ultisol soils. One solution that can be done to deal with this problem is through the selection of resistant corn varieties and the use of soil amendments. This paper is based on four experiments conducted at the Seed and Greenhouse Laboratory of the Faculty of Agriculture, Universitas Syiah Kuala, Darussalam Banda Aceh from June 2017 to July 2019. To analyze the level of resistance of corn varieties to water and nutrient deficiencies, nine corn varieties were tested using PEG6000. and an experiment on the vegetative response of corn to organic fertilizer on Ultisol soil from Jantho, Aceh Besar. The general objective of this study was to obtain corn varieties that were resistant to water and nutrient stress on Ultisol soil. The study consisted of four experiments using a factorial completely randomized design (CRD) for Experiments 1, 2, and 3, and a split-plot design for Experiment 4. Nine varieties of corn were tested in Experiments 1 and 2, respectively. are Anoman 1 (V1), Lamuru (V2), Gumarang (V3), Srikandi Kuning (V4), Sukmaraga (V5), Bisma (V6), Laga ligo (V7), Arjuna (V8), and NK-Jumbo (V9 ), while in experiments 3 and 4 used three varieties of corn selected in experiments 1 and 2 with low adaptability. Experiment 1 used three treatment levels, namely 0% PEG solution (0 MPa), 10% PEG (-0.19 MPa), and 20% PEG (-0.67 MPa) which were tested on seed germination of nine corn varieties. The variables observed in this experiment included germination rate (DB), growth rate (KcT), vigor index (IV), growth uniformity (KsP), germination stress index (UTI), time required to reach 50% of total germination (T-50). ), root dry weight (BKA), shoot dry weight (BKT), BKA/BKT ratio, and proline content. Experiment 2 was carried out to see the response of physiological changes in corn plants to four levels of nutrient stress treatment, namely: C (control or given complete nutrient solution using Haogland solution, C-P (phosphorus stress treatment or not given phosphorus), C-K (potassium stress treatment or not given potassium), and C-Mg (magnesium stress treatment or not given magnesium). The observed variables were stomatal density, and stomatal index, total stomata, total chlorophyll, shoot dry weight, root dry weight, ratio shoot-roots, and plant biomass, as well as the concentration of P, K and Mg of corn leaf vegetative growth phase. In Experiment 3, there were three factors studied, namely variety, two levels of water stress, namely control given water 75% field capacity (S0) and the water stress treatment was given water 37.5% field capacity or KL (S1), and as the third factor was given organic fertilizer with four treatments, namely without application of soil amendment (B0), given rice straw 10 t ha-1 (B1), given biochar 10 t ha-1 (B2), and given rice straw 5 t ha-1 + biochar 5 t ha-1 (B3) at Ultisol soil. The variables observed in this experiment included total stomata, leaf area, number of leaf curls, shoot dry weight, root dry weight, biomass weight (top dry weight + root dry weight), proline content, stress sensitivity index (IKS), and tolerance index (ITC). Experiment 4 tested the effect of abiotic stress on corn growth on Ultisol soil. The abiotic stresses consisted of 8 (eight) treatments, namely: C0 (without drought stress/with 75% of field capacity), C1 (dry stress/37.5% field capacity), C2 (without phosphorus stress), C3 (phosphorus stress/no given P), C4 (without potassium stress), C5 (potassium stress/not given K), C6 (without magnesium stress), and C7 (magnesium stress/not given magnesium).The observed variables were the number of stomata, total chlorophyll content, cob dry weight, root dry weight, shoot dry weight, and plant biomass weight.
The results of Experiment 1 showed that water stress in the germination phase affected the viability and vigor of the seeds as well as the growth characteristics of corn sprouts. In the control treatment (PEG 0% or normal conditions), seed germination grew normally, but under water stress conditions (PEG 10% and 20%), all corn germination variables decreased or had lower values, but the responses differed depending on the corn varieties. Varieties also differ in germination of seed vigor (GR), vigor index (VI), growth speed (KcT), root dry weight (BKA), shoot dry weight (BKT) and BKT/BKA ratio, and Tn-50. The difference also occurred in proline content, but the difference in varieties did not affect root weight (BA), shoot weight (BT), growth readiness, and stress index of corn germination. The results of Experiment 2 showed that P, K, and Mg nutrient stress had an effect on changes in the physiological character and vegetative growth of corn plants. The adaptability or level of resistance among corn varieties to phosphorus, potassium and magnesium nutrient stress depends on the corn variety. The corn variety which was relatively more resistant to nutrient stress was Anoman 1, while the weak (low) adaptability was shown by the NK-Jumbo, Srikandi Kuning and Lamuru varieties. The results of Experiment 3 showed that water stress had an effect on physiological characters, proline content, and plant growth of three corn varieties with low adaptability (NK-Jumbo (V9), Srikandi Kuning (V4) and Lamuru (V2), except for shoot dry weight. The growth characteristics of the three corn varieties after being given organic fertilizer did not show any significant difference. Significant interactions with factor treatments occurred between corn varieties under water stress conditions, between corn varieties with organic fertilizer application, and between water stress and organic matter application. From results of Experimental 4 it was found that the number of stomata, total chlorophyll, cob weight, root weight and corn biomass had significant differences between the three corn varieties.
In general, it can be concluded that abiotic stress, both water stress and nutrient stress (P, K, and Mg) affect all observed variables and there is a significant interaction between varieties and abiotic stresses on Ultisol soils.