Assessment of Growth and Productivity on Four Black Pepper Varieties ( Piper nigrum L. ) in Three Target Provinces of Vietnam

Black pepper varieties, namely “Vinh Linh”, “Lada”, “An Do” and “Loc Ninh” were planted in three different ecological regions: Dak Lak, Gia Lai and Dong Nai in order to compare the growth ability, productivity, and quality of peppercorn. The experiments were designed in the Randomized Complete Block Design (RCBD) with four replications. The results of study have been indicated that “Vinh Linh” and “Lada” both varieties performed better crucial parameters of growth, productivity and yield, after 36 months planted. Although having greater growth parameter in the location of Dong Nai prov-ince, four varieties showed lower yield than other regions. By contrast, the four pepper types achieved the highest yield in Gia Lai, followed by Dak Lak. With respect to peppercorn quality, “Vinh Linh”, “Loc Ninh” and “Lada” achieved requirements of Vietnamese Standard (TCVN 7036:2008) including bulk density: 535.69 - 612.72 g/l; piperine: 4.06 - 4.31 g/100g and volatile oil at 2.72 - 3.16 ml/100g. In contrast, “An Do” variety presented the poorest level of piperine (3.78 g/100g), and unachieved requirements. analysis: Data is collected and analysed ANOVA using SAS 9.1 statisti-cal software.

Engineering duced annually around 268,500 ton peppercorn and exportation 285,292 ton to global market [1].
Despite having great achievements, pepper industry in Vietnam is assessed as unsustainable development, which is highly likely to have resulted from less diversity of varieties, uncontrolled areas, spread of diseases and climate change.
Additionally, results of studies related to pepper breeding are limited and inequal with demands, as a result, fewer pepper types are planted in Vietnam. Piper nigrum in Vietnam has been clarified as three general groups following size of leaf: small leaf, medium leaf and large leaf [1]. The majority of local pepper types is "Vinh Linh", accounting for around 97.1%, 84.6% and 100% in the Western highland, Southern and Northern regions respectively. The crop however, is vulnerably injected by diseases, especially quick death caused by Phytophthora capsici. Similarly, the global market competition is becoming significant; food quality, hygiene and safety are increasingly and strictly controlled which are the detrimental barriers for Vietnamese pepper products.
With respect to sustainable development in the pepper industry, the diversity of pepper types plays a crucial role in improvement of quality and productivity, coping with climate change as well as spreading diseases. Currently, different zones have a few local pepper types which were mostly selected by farmers or immigrated from other places. Furthermore, pepper types often high demand for specifically optimal living conditions, therefore, assessment of potential capabilities of different pepper types at specific regions in Vietnam is absolutely essential to suggest an appropriate group of pepper types for each area.

Materials and Methodology
Description of the study site: Experiments are conducted at three target provinces, namely Dak Lak, Gia Lai and Dong Nai, and four varieties: "Vinh Linh", "Loc Ninh", "Lada" and "An Do" during a three year period (2018-2020).
Several details of sites are described on Table 1. Agricultural practices in the research are followed by Vietnamese agricultural practice of MARD [2]. Number of berries•spike −1 : Total fruits on the spike, the process is taken all spike which use to measured spike length above.
• Yield of peppercorn was harvested in 2020, when plant age was 3 years old, and measured separately all plants on the experiment in order to assess the dry weight•plant −1 . Total yield (kg/ha) = yield•plant −1 × total bearing plant•ha −1 .
Data analysis: Data is collected and analysed ANOVA using SAS 9.1 statistical software. Table 2 indicated anaverage main shoots per vine ranging from 3.45 to 6.98 shoots. "Vinh Linh" and "Lada" both have higher and significant difference in the number of main shoots in three regions, in comparison with others (p < 0.01). "Loc Ninh", by contrast, has the lowest number of shoots•vine −1 with an average of 3.45 shoots. Additionally, it is noticeable that crops which planted in Dong Nai, have performed better in main shoots than the rest of two regions.   considerably differences in spike's length and number of berries•spike −1 compared to other locations. "An Do" and "Vinh Linh" varieties both presented better measurements on the berries and length of spike in three different regions (see Table 3). "Lada", despite of good growth, measures of spike's length and number berries•spike −1 were the lowest.

1) Growth characters of four pepper types
2) Yield and quality of four pepper types Figure 1 shows that"Vinh Linh" and "Lada" have presented higher yield than others. Additionally, all crops performed the great productivity in the locations of Gia Lai and Dak Lak provinces. Overall, "Lada" achieved the highest yield (702.04 kg/ha) in three different provinces, followed by "Vinh Linh" and "An Do" and "Loc Ninh" with 675.86 kg/ha, 455.87 kg/ha and 366.50 kg/ha respectively.
Bulk density is a physical factor which determines berry weight. Basing on bulk density and standard of TCVN 7036:2008, peppercorn which is produced from "An Do" and "Lada" cultivars are classified as special; "Vinh Linh" is graded I; and "Loc Ninh" is graded II. Pepper types in Gia Lai achieved better bulk density (600.56 g/liter) than Dak Lak and Dong Nai (see Table 4).
Piperine and volatile oil directly affect the spiciness and aroma of peppercorn.     [14] and Ibrahim, Sukumara Pillai [10]. The findings of the study are also similar to the results of obvious researches in Vietnam. Nhung, Oanh [15]; Oanh, Huy [16]; Quyen, Dan [17] and Ton, Binh [18] all of them agreed that "Vinh Linh" and "Lada" both varieties not only achieve great measures of growth, but also have higher yield and quality of peppercorn.

Conclusion
Research has investigated and compared growth parameters, yield and pepper- are highly likely to be advised to plant popularly in these areas. Besides, due to limited time and resources, plants do not have adequate time to perform potential growth, yield and quality of peppercorn, therefore, continuity of the study for next several years is necessary.