Variation in Root-Related Traits Is Associated With Water Uptake in Lagenaria siceraria Genotypes Under Water-Deficit Conditions

Abstract

In many agricultural areas, crop production has decreased due to a lack of water availability, which is having a negative impact on sustainability and putting food security at risk. In plants, the plasticity of the root system architecture (RSA) is considered to be a key trait driving the modification of the growth and structure of roots in response to water deficits. The purpose of this study was to examine the plasticity of the RSA traits (mean root diameter, MRD; root volume, RV; root length, RL; and root surface area, SA) associated with drought tolerance in eight Lagenaria siceraria (Mol. Standl) genotypes, representing three different geographical origins: South Africa (BG-58, BG-78, and GC), Asia (Philippines and South Korea), and Chile (Illapel, Chepica, and Osorno). The RSA changes were evaluated at four substrate depths (from 0 to 40 cm). Bottle gourd genotypes were grown in 20 L capacity pots under two contrasting levels of irrigation (well-watered and water-deficit conditions). The results showed that the water productivity (WP) had a significant effect on plasticity values, with the Chilean accessions having the highest values. Furthermore, Illapel and Chepica genotypes presented the highest WP, MRD, and RV values under water-deficit conditions, in which MRD and RV were significant in the deeper layers (20–30 and 30–40 cm). Biplot analysis showed that the Illapel and Chepica genotypes presented a high WP, MRD, and RV, which confirmed that these may be promising drought-tolerant genotypes. Consequently, increased root diameter and volume in bottle gourd may constitute a response to a water deficit. The RSA traits studied here can be used as selection criteria in bottle gourd breeding programs under water-deficit conditions.

Variation in Shoot, Peduncle and Fruit Growth of Lagenaria siceraria Landraces

“…The grouping of landraces with similar growth trends in shoots and fruits in a biplot ( Figure 1 ) concurred with the clustering of L. siceraria landraces with similar root characteristics in Chile and Mozambique [ 54 ]. This was evidence of correlation among different L. siceraria landraces based on their morphological attributes, as facilitated by the biplot [ 15 ].…”

Rootstocks Comparison in Grafted Watermelon under Water Deficit: Effects on the Fruit Quality and Yield

“…Our preliminary results supported the idea that fine roots are responsible for water uptake and productivity in Chilean bottle gourd accessions under water deficit conditions [ 26 ]. In the present study, the Chilean bottle gourd accessions (Illapel and Osorno) and ‘GC’ were classified as tolerant when used as rootstocks and consistently showed high values for root architectural traits (volume, length, and surface area) compared to ‘BG-48’ and ‘Philippines’, which are susceptible to water deficit.…”

“…However, when the values were calculated with total cumulative fruits (marketable and non-marketable fruits), significant differences were observed in the yield response factor of the grafted watermelon plants with the different rootstocks; in this case, the susceptible accessions were ‘BG-48’ ( = 1.5) and ‘Philippines’ ( = 1.1), whereas the accessions ‘GC’, ‘Osorno’ and ‘Illapel’ were considered tolerant to water deficit. These results help to support the idea that Chilean bottle gourd accessions are considered tolerant to water deficit based on the response of root traits and water uptake [ 26 ].…”

“…It is also a measure of drought tolerance. In this sense, to enhance agriculture’s sustainability, it is necessary to develop genotypes with high yields and water productivity [ 26 ]. A review that summarizes the results of crop water productivity values for irrigated watermelon from seventy-seven studies showed that the range of WP was extensive, ranging from 2.70 to 14.33 kg m −3 [ 35 ].…”

“…Despite the above, the genetic resources of L. siceraria remain under-utilized and largely unexplored globally for producing grafted watermelon, especially to improve fruit yield and quality in water-limited environments. Similarly, some local bottle gourd accessions in Chile have been identified with high levels of drought tolerance [ 26 ]. However, these genotypes have never been evaluated as potential rootstocks for watermelon production in local production areas.…”