It is predicted that drought will be more frequent and sustained in the future, which may affect the decline of rubber tree production. Therefore, it is critical to research some of the variables related to the drought-resistance mechanism of the rubber tree. As a result, it can be used to guide the selection of new rubber drought-resistance clones. The goal of this study was to identify drought-resistance mechanisms in rubber clones from the high drought factor index (DFI) group using ecophysiological and biochemical variables. The treatments consist of two factors, namely water deficit and contrasting clones based on the DFI variable. The first factor consisted of three levels, namely normal (fraction of transpirable soil water (FTSW) > 0.75), severe water deficit (0.1 < FTSW < 0.20), and recovery condition (FTSW > 0.75 after rewatering). The second factor consisted of seven clones, namely clones G239, GT1 (low DFI), G127, SP 217, PB 260 (moderate DFI), as well as G206 and RRIM 600 (high DFI). RRIM 600 had the highest DFI among the other clones as a drought-tolerance mechanism characteristic. Furthermore, clones RRIM 600, GT1, and G127 had lower stomatal conductance and transpiration rate than drought-sensitive clone PB 260. As a result, as drought avoidance mechanisms, clones RRIM 600, GT1, and G127 consume less water than clone PB 260. These findings indicated that clone RRIM 600 was a drought-resistant clone with drought tolerance and avoidance mechanisms.

Spent bleaching earth (SBE) is by-product of cooking oil processing industry of crude palm oil (CPO). Palm oil industry is growing every year, followed by population growth and consumption of cooking oil so that the greater volume of waste generates SBE. An innovation is needed to anticipate the problem of SBE waste in agricultural sector, dealing with a filler component in the production of NPK fertilizer additives. This study aims to determine proline response, growth and yield of the maize to fertilization NPK with SBE-based filler. The experiments used Randomized Complete Block Design (RCBD) with the treatments of NPK filler (15:15:15) consisting of BC (brown clay), SBE and DBE (deoiled bleaching earth) at a dose of 6 g polybag-1. The results showed that the use of SBE gave the same effect on plant height, leaf number, stem diameter and 100-seed weight, but the use of SBE could increase 61.15% of proline activity. SBE can substitute filler on the additional materials of NPK fertilizer.

Kayu putih (Melaleuca cajuputi) waste has the potential via in situ biochar briquettes to overcome the low availability of nitrogen in soil. This study evaluated the short-term effects of in situ biochar briquettes on nitrogen loss reduction and determined an optimum scenario for hybrid rice grown in an agroforestry system among kayu putih stands. This three-year experiment (2019–2021) was conducted using a randomised complete block design factorial with three blocks as replications. The treatments included biochar briquettes made from kayu putih waste (0-, 2-, 4-, and 6-grain plant⁻¹ or 0, 5, 10, and 15 tonnes ha⁻¹) and urea fertiliser (0, 100, 200, and 300 kg ha⁻¹). The results demonstrated that the eco–environmental scenario was the most efficient strategy that improved the soil quality, the physiological characteristics, and the yield of the hybrid rice with the optimum application of the biochar briquettes at 5.54-grain plant⁻¹ and the urea fertiliser at 230.08 kg ha⁻¹. This alternative approach illustrated a reduction in both the usage of urea fertiliser and the loss of nitrogen by 23.31% and 26.28%, respectively, while increasing the yield of the hybrid rice by 24.73%, as compared to a single application of 300 kg urea ha⁻¹ without biochar briquettes.

A family of Sigmoidal non-linear models is commonly used to determine the critical period of weed control (CPWC) and acceptable yield loss (AYL) in annual crops. We tried to prove another non-linear model to determine CPWC and AYL in a soybean agroforestry system with kayu putih. The three-year experiment (from 2019–2021) was conducted using a randomised complete block design factorial with five blocks as replications. The treatments comprised weedy and weed-free periods. Non-linear models comprised 45 functions. The results show that the Sigmoidal and Dose-Response Curve (DRC) families were the most suitable for estimating CPWC and AYL. The best fitted non-linear model for weedy and weed-free periods in the dry season used the Sigmoidal family consisting of the Weibull and Richards models, while in the wet season the best fit was obtained using the DRC and Sigmoidal families consisting of the DR-Hill and Richards models, respectively. The CPWC of soybean in the dry season for AYL was 5, 10, and 15%, beginning at 20, 22, and 24 days after emergence (DAE) and ended at 56, 54, and 52 DAE. The AYL in the wet season started at 20, 23, and 26 DAE and ended at 59, 53, and 49 DAE.

The non-aromatic genotypes are known to possess the capacity to produce aromatic cocoa beans when planted in strategic environments with specified soil compositions. Therefore, this study aimed to identify genetic responses to the flavor of cocoa beans in different growing environments. A total of three superior cocoa clones, namely the aromatic (MCC 02) and non-aromatic genotypes (Sulawesi 1 and Sulawesi 2), were used. A completely randomized block design was utilized with three replications at four locations with different agro-climatic types, including Jember in East Java (dry area, low land), Pringsewu (dry area, low land), Pesawaran (wet area, medium land) in Lampung, and Soppeng in South Sulawesi (dry area, medium land), which served as the control location of FFC producers. Additionally, the sensory properties were assessed by three trained and certified panelists. The results showed that both genetic and environmental factors significantly influenced the flavor characteristics of Indonesian cocoa beans. Non-aromatic genotypes cultivated in Pesawaran and Soppeng demonstrated the ability to produce aromatic beans. Significant differences were observed in the volatile characteristics of aromatic and non-aromatic genotypes. Compounds such as alkaloids, pyrazine, and alcohol dominated cocoa beans produced in the aromatic group, while non-aromatic genotypes were dominated by terpenoids. Variations in elements and soil conditions contributed to the changes in the sensory characteristics of cocoa beans, ultimately leading to aromatic characteristics.

Nitrogen (N) fertilizer efficiency can increase by adding N-(n-butyl) thiophosphoric triamide (NBPT) and N-(n-propyl) thiophosphoric triamide (NPPT) as urease inhibitor in urea fertilizer and adding 3,4-dimethyl pyrazole phosphate (DMPP) as nitrification inhibitor in ammonium sulfate (ZA) fertilizer. The research objectives were to examine the effectiveness of urease inhibitor (NBPT and NPPT) and nitrification inhibitor (DMPP) on the physiological activity and oil palm yield on red-yellow podzolic. Field experiment was done using a Randomized Complete Block Design (RCBD) of single factor and three replications as block. The single factor was nine fertilization treatments of urea with or without urease inhibitor, and ZA with or without nitrification inhibitor. The use of urease inhibitors decreases the amount of volatilization and N loss fertilizer. The higher dose of broadcasting N fertilizer (on the same type of fertilizer) resulted in the higher amount of N loss and volatilization. All fertilization treatments did not have any significant influence to the width and the length of opening stomata, nitrate reductase activity (NRA), N concentration in oil palm leaf, Oil Extraction Rate (OER), and Free Fatty Acid (FFA). Meanwhile, The oil palms at yellow red podzolic applied with urea 195 kg/ha combined with 0.12% of NBPT-NPPT resulting in higher fresh fruit bunch productivity.